S229 6019 2_3420_3803_Magnetic_Tape_Subsystem_Reference_Guide_Jan80 2 3420 3803 Magnetic Tape Subsystem Reference Guide Jan80

S229-6019-2_3420_3803_Magnetic_Tape_Subsystem_Reference_Guide_Jan80 S229-6019-2_3420_3803_Magnetic_Tape_Subsystem_Reference_Guide_Jan80

User Manual: S229-6019-2_3420_3803_Magnetic_Tape_Subsystem_Reference_Guide_Jan80

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IBM 3420/3803
Magnetic Tape Subsystem

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Reference Guide

'PREFACE
, .This reference~guide and associated video presentation were created by FE Service Plan'. 'ning and Support to assist you in maintaining the 3420/3803 Magnetic Tape Subsystem.
Two approaches were taken:

L', New information is included as a result of IR data indicating the areas where more
in-depth knowledge is needed.
2.

Current information, which is frequently used, has been condensed from the MLM/ :
Pathfinder and included here.

The guide is divided'into four major sections. Each of these sections contains information which logically fits into that section. Take the time to glance through the guide and
get an idea of what is included.
Pay particular attention to the "NTF Service Checks" portion of each area. It is intended
.. to give you a list of actions to be performed which may help eliminate many call-back
situations. When you write a no trouble found IR (major unit 960) try to use unit/cause
codes which best describe the reported failure symptom so that FE SP/S may have a
better understanding of areas of the machines with intermittent problems.

THIRD EDITION (January 1980)
This is a major revision of, but does not make S229-6019-1
obsolete.
Address any comments concerning the contents of thls publication to: IBM Field
Engineering Service Planning, Department 96C, BUilding 005, Tucson, Arizona 85744.
© Copyright International Business Machines Corporation 1978, 1980

CONTENTS
GENERAL
3420 Subsystem Characteristics. . . . .
3803 Model 3 and 3803 Modell Differences
Recording Philosophy . . . . . . . .
Understanding EREP1. . . . . . . .
Procedure for Scoping 3420 Tape Unit Sense Bits on Logic Board
3420/3803 Status/Sense Bytes ~ . . . .' . . .
3803-2/3420-3Tiuough 8 Tape Drive Sense Atialysis. .
3803/3420 Online Tests
What is Where in the MLM?
Common Abends. . . .
Tools and Test Equipment

3
5
9
17
19
20
27
31
35
39

MEDIA
45
47
51

, IRD PEP Specialist
Magnetic Tap~
CommOl1 Media Related Problems

3420 "
Read/Write Service Techniques
Read/Write Failure Analysis .
Read/Write Head Service Hints .
3420 Read/Write NTF Ch~ck1ist .
Tape Developing Procedure
Developed Tape Samples . . .
3420 RD/WR Data Flow . . .
,3420 Tape Motion Service Techniques.
3420 Tape Motion NTF Checklist .
3420 Tape Motion . : . . .
3420 Power Service Techniques
342Q Power NTP Checklist
, 34:20 Power - DC Voltages .
3420/625,0- Conversion-Tips .
34 20 PM Schedule, . . .'
3420 Sales Feature Codes, .
3420 (All Models) Status Identifier.
3420 ECA Checklist ." .
Models3, 5, 7 - AI' BO'ard ,. .
Models 4, 6, 8 - Al Board. .
.Card Jump~rs - Models 3, 5, 7
Card Jumpers - Models 4,6,8 '
'Co1l1mon 3420 Part Numbers.
'FlafBelt Pneuf!1atic Supply

.,
.

53
61
63
65
67
69
71
73
77
79
83
85
87
91
95
99
101
103
117
119
, 121
125
129
131

CONTENTS (continued)
3803
3803 Modell Data Flow
3803 Model 2 Data Flow
3803 Microprocessor Instruction Format.
3803 Microprocessor Tips. . . . . .
Current ALU Patches . . . . . . .
Current 3420/3803 Related Software Zaps
3803 Channel Interface . . . . .
3803 DC Voltages . . . . . . .
3803 Mod 1 to 2 - 6250 Conversion Tips
3803 Conversion Tips from Data Bank
3803 Preventive Maintenance Schedule
3803 Sales Feature Codes. . .
3803-1 Feature Identifier . . .
3803-1 Feature Installation Times .
3803-2 Feature Installation Times
3803 ECA Checklist. .

139
141
143
145
149
153
155
163
165
169
173

175
177
179
. 183
185

197

Bibliography . . . .
Index . . . . .
Reader's Comment Form

199

" GENERAL

3420 SUBSYSTEM CHARACTERISTICS

Tape Speed (Read or Write)
(ips)
(cm/sec)
6250 Read
1600 Read
6250 Write
1600 Write

Access Time, nominal*(ms)
Access Time, nominal*(ms)
Access Time, nominal*(ms)
Access Time, nominal*(ms)

Forward Start Time, nominal**(ms)

Model 3

Model 4

Model 5

Model 6

Model 7

Model 8

75
190,5

125
317,5

200
508

2.0

4.0

2.3
4.0
2.1
3.0

1.8

1.4

4.0

1.1

2.9

1.6
2.6
1.5
2.0

2.0

1.65
0.95
1.28

1.4

1.1

1.3

.08

2.9

Data Rates (Kb/sec;Kd/sec):
6250 bpi
1600 bpi PE
800 bpi NRZI (9-Track)
800 bpi NRZI (7-Tra.ck)
556 bpi NRZI (7-Track)
200 bpi NRZI (7-Track)

120/240
60/120
60
41.7
15.0

Passing Times per Byte (usec):
6250 bpi
1600 bpi PE
800 bpi NRZI
556 bpi NRZI
200 bpi NRZI

8.3
16.7
24.0
66.7

Passing Times, IBG (ms):
6250 bpi
9-Track(PE and NRZI)
7-Track'(NRZI)

8.0
10.0

Rewin.~·

Time (2400-foot reel)

Rewind/Unload Time:
(2400-fQot reel) (sec)
Load Operation, approximate time (in
sec) to 'tape unit ready' (after
'reel/cartridge is mounted and
LOAD/REWIND is pressed)

470/940

1201240

2.133
8.3

4.0
8.0

200/400
100/200
100
69.5
25.0

5.0
10.0
14.4
40.0

4.8
6.0

780/1560
200/400

1.28
5.0

2.4
4.8

320/640
160/320
160
111.2
40.0

3.1
6.2
9.0
25.0

3.0
3.75

1250/2500
320/640

0.80
3.1

1.5
3.0

* Read access time is the interval fr.om initiation of a Forward Read command given to the t-ape control
whe~ tape is not at load point, until the first data byte is read when tape is brought up to speed from
stoppe€! status.
, *Write access time is the interval from the issuance of a Move command given to ~he tape unit when tape
is not at load point, until the first data byte is written on tape when tape is brought up to speed from
stopped status.
**Start time is the int~rval from the issuance of a Move command to the tape unit, until tape attai~s
90% of specified velocity.
.

3803 MODEL 3 AND 3803 MODEL 1 DIFFERENCES
The Model 3 was designed to attach to 370/ 115s and 125s. It is basically a Modell with
three major differences. These differences are required because the 115 and 125 don't
use a standard 370 channel.
- ALUI is modified to interface with the channel on the 115 and 125 and translate the
activity to 370 channel sequences which the rest of the 3803 understands.
- Hardware logic called AUTO DATA TRANSFER is provided to handle the data transfer. It includes the byte counter.
- A 32-BYTE DATA BUFFER is provided for reading and writing. This large a buffet
is required in the event that data crosses a page boundary. When this happens, time
is required for ALUI to set the address of the new page back into the data address control in the 115 or 125.
The 3803 Model 3 tape subsystem connects to the Magnetic Tape Adaptor (MT A) interface of system 3115 or system 3125. The term MT A interface refers to a set of lines over
which control and data signals are exchanged between the control unit and the MT A
portion of the system.
The basic 3803-3 Control Unit consists of a MT A interface attachment section, a data
buffer section, a microprogram section, a read section, a write section, a tape unit interface and a CE section.
I/O commands received from CPU through MTA are executed with microprograms resident in two independent read-only storage (ROS) units within the 3803-3 Control Unit.
One ROS controls the MTA interface lines while the other ROS controls the tape unit
interface.
The 3803-3 Control Unit operates in burst mode for all data transfers and executes commands received across the interface, performing one command on a single tape unit at a
time.
When a 3803 Mode13 is taken offline, all functions from the control to the tape unit
become the same as a Modell 3803.

RECORDING PHILOSOPHY
Types of Codes:
NRZI
PE
GCR

Non-Return to Zero Indicating
Phase Encoding
Group Coded Recording

The progression of IBM digital recording from NRZI to PE to GRC is the result of IBM's
effort to provide the customer with the lowest cost and highest reliability tape storage
devices.
NRZI coding utilizes a chnage in flux to indicate a one and no change to represent a zero.
NRZI tapes can be written in densities of 200, 556 bpi in 7 -track format, and 800 bpi in
9-trace format. (See example A.)
PE coding utilizes a change of magnetic flux in the positive direction to indicate a one
and a change in the negative direction to indicate a zero. PE tapes are written in 1600
bpi 9-track density only. (See example B.)
GCR coding utilizes a combination of NRZI and PE to achieve the highest density available on IBM drives. Density for GCR is effectively 6250 bpi. (See Example C.)
Group Coded Recording - 6250 bpi
Group Coded Recording (GCR) offers many advantages over previously used recording
methods. This recording offers higher reliability even with existing tape libraries.
Greatly expanded error correction capability has been engineered into GCR. Higher
data rates and lower access times give higher throughput and reduced channel time, resulting in higher system performance. Data is compacted on tape, reducing rewind
times, shortening the length of tape required for a data set, reducing the number of
reels, reducing mounts and dismounts, and improving overall tape handling. Other
advantages exist, but here we wish to discuss only the recording technique.
The data is still recorded in blocks, or groups of characters. A block of data may be
a single character or byte, or a number of bytes as determined by the programming
system used. The significant improvements in the GCR mode are:
1.
2.
3.

The information data is recorded at an effective density of 6250 bytes per inch.
The separation between blocks (IBG) is 0.3 inch, and,
That simultaneous errors in any two of the nine tracks are corrected automatically.

A GCR block consists of a preamble, data and a postamble. The preamble and postamble are each 80 bytes long and serve to synchronize the read detection circuits in a
manner similar to previous 1600 bpi subsystems. The data portion of the block consists
of the following:
5

RECORDING PHILOSOPHY (continued)
1.

For every seven bytes of channel data, an ECC character (error correcting code)
is generated and these eight bytes, called a data group, are encoded into ten
bytes, called a storage group, which are then written on the tape. There will be
as many of these ten byte storage groups as there are multiples of seven channel
data bytes in the record block. The last group of the record block may contain
up to 158 storage groups.

The remainder or last group of the channel data bytes (zero to six bytes) is
encoded with whatever "pad" bytes are necessary, an auxiliary check character,
and the ECC character generated from these into a ten-byte residual group.
This residual data group is created for every block recorded, even though no
residual bytes are found in the record and will always be ten bytes long. The
auxiliary check character verifies read and write operations.

End of data is signaled by a unique subgroup of five bytes immediately preceding
the residual group.

Following the residual group, a ten-byte CRC (Cyclic Redundancy Check) group
is encoded. This group, with the auxiliary check character, ensures the integrity
of the read and write operation including verifying any error corrections which
may have taken place.

Interleaved into the recorded block, after every 158 storage groups, is a resync
burst. This burst allows the tape control unit to put back into full operation any
track(s) which may have lost synchronization or dead tracked due to tape
defects. This action limits dead tracking for greater throughput.

6250 bpi does not relate to actual writing density on tape but to effective data density
Actual density (9042 bpi) is greater due to the formatting and enGoding, but this formatting and encoding is transparent to the user. The power of the format and encoding
method is such that reliable error correction occurs for any two tracks Simultaneously
in error. Also, tracks are not immediately dequeued or 'dead tracked' when an error
occurs as they were in the past. It is thus conceivable that a block could have errors in
all nine tracks and appear to the user to be read error-free so long as only two tracks have
errors at any given instant.
6250 bpi, combined with 0.3 inch IBGs, provides for greatly improved channel data
rates and access times.

RECORDING PHILOSOPHY (continued)
NRZI

(Example A)

--1

Write Signal

Analog Read Signal

Read Digital Output

(Example B)

Write Signal

Read Digital Output

RECORDING PHILOSOPHY (continued)
GCR

(Example C)

J I

n_ _ _ _

I I I

I..-.-..________

Physical Size of a 4K Byte Record

NRZI (800)

PE (1600)

GCR (6250)

UNDERSTANDING EREPI
EREP is designed to help you decide if you have a machine problem or defective media,
as well as giving you a good idea of how your 3420s are performing. EREPI, with its
enhancement package, is even more useful than previous EREP versions. EREPI guidelines are presented here to assist the CE in managing his 3420 account.
IRD (Information Records Division) is using a criteria of one temporary write error per
5,000 SIOs and one temporary read error per 70,000 SIOs as a reference for an average
running 3420/3803 customer account. We agree with these numbers with the understanding that they are intended to be a national average. They are not a certain indication of
reliability to be obtained in individual accounts because of the influence of unmeasured
variables (ie, customer block size).
The IRD criteria is used in determining temporary read or write error criteria figures on
the following flowcharts. EREPI parameters should be used to produce a 3420/3803
Summary Output with threshold values at one temporary read and fifteen temporary
write errors. These are suggested initial threshold values which CE may wish to change
later.
All permanent errors should be investigated to an acceptable conclusion and all temporary
error quantities not meeting criteria figures should be recorded and tracked to determine
cause of outside-criteria conditions.
Sheet 1

UNDERSTANDING EREPI (continued)
Begin 3420
E R EP Analysis
Look at "permanent
error summary"
section

Yes
Go to
Sheet 7
Temporary
Error
Analysis

If several permanent
errors are listed try
to determine if one
3420 or one volume
of tape appears to be
at fault.

Permanent
Write
If the 3420 is now
working properly
approach problem
as a media failure.
Try to recreate
write failure using
same tape and 3420,
if possible. Use proc~dure shown on
Permanent Read
Analysis Sheet 3,
except perform
wri te instead of
read. Also see M LM
5A - 105.

Permanent
Read
Go to
Sheet 3
Permanent
Read
Analysis
I
L ______ ,

I
I

Use Sense
Data to Enter
MLM or PF

Sheet 2

UNDERSTANDING EREPI (continued)
Permanent Read Error
Permanent Read Error
(From Sheet 2)

Yes

Read tape on tape unit
where failure occurred.

Online: Run "FRIEND" (OLT T0200A) or
have customer run "ditto" or equivalent tape-to-tape job using the failing tape as input.
Offline: If 3803 is available perform read
command from CE panel. Turn on
"stop on data flow check" switch.

Locate and mark failure
with felt pen - read tape
on another tape unit

Permanent Read Error Analysis Chart

Reference MLM 00-011
Sheet 3

UNDERSTANDING EREPI (continued

Yes
Return to original
tape unit.

Look for physical
damage on tape.

Refer to section on developing tape.

Develop tape.

Refer to section
on tape damage.
Permanent Read Error Analysis Chart
Sheet 4

UNDERSTANDING EREPl(continued)

: Refer to tape samples elsewhere in this book.

Repai r cause of
damage.

Yes
Scope failing
block off line.

. The purpose of scoping a permanent read
error is to locate the failure within the
block and determine the cause. Proceed
as follows:
1. Locate the failing block offline.
2. Loop on the failing block:
a. Read forward-backspace on forward
read failures.
b. Read backward-forward space on
backward read failures.
3. Refer to MLM 00-012 for more information.

Permanent Read Error Analysis Chart
Sheet 5

UNDERSTANDING EREPI (continued)
Use the FRIEND program to scope permanent read errors online:
Note: Don't use channel command word
(CCW) chains. Reading the bad
record breaks the chain.
1. Locate the failing block with the control
unit offline.
2. I Set up a program loop to read forwardbackspace or read backward-forward
space whichever is applicable.
3. By altering the channel command word
(CCW) byte count, the command-out
response to service-in will set the stop
trigger in the tape control at any byte
chosen. Sync external on the stop trigger to examine any portion of the block
in detail.
Note: Detailed observation of a PE block
is difficult due to normal distortion of the PE signal and the high
amount of skew the PE detection
circuits can tolerate. Examine
several tracks at comparable points,
looking for noticeable differences
in levels and waveforms. A record
containing excessive phase shift is
usually indicated by multi-track
error (MTE) or read write register
(R/W Reg) vertical redundancy
checks (YRC). Check the tape unit
that wrote the tape for a possible
defective write driver. Refer to
MLM 00-012 for more information.
I

Scope failing
block on line.

Call area technical
assistant or branch
office tape specialist.

· If you cannot determine the cause of the
permanent read error, save the tape and any
: information you have gathered for use by
· your branch office or region tape specialist.
· A permanent read error can cost the cus: tomer considerable reconstruction and rerun
time. There should be NO undefined permanent read errors.

Permanent Read Error Analysis Chart

Sheet 6
14

UNDERSTANDING EREPI (continued)
Temporary Read
Temporary Write
Error Analysis
(From Sheet 2)

I
Look at "CUA Statistics"
section of EREP printout.

I
Look at the three
columns pertaining to:
• Temp RDS
Temp WRTS
SIO Count

•
•

Using the three columns
indicated above, determine
if temporary error failure
rate exceeds criteria of:
1. Temp write error
per 5,000 SIOs
2. Temp read error
per 70,000 SIOs

Any CUA entry meeting criteria
may be ignored. Those not
meeting criteria should be
logged in a manner so as to
give the CE a method of
spotting consistently outside
-criteria volumes or CUAs.
(See Note 1)

Note 1:
One logging method would be a grid chart
with CUAs plotted along vertical edge and
volume IDs plotted along horizontal edge.
Number of temporary errors could be
entered at appropriate intersections. A consistent horizontal pattern of error entries
would indicate a possible tape unit problema vertical pattern would indicate a bad volume of tape.

Sheet 7

PROCEDURE FOR SCOPING 3420 TAPE UNIT SENSE BITS ON LOGIC
BOARD
•
•
•
•
•

Take 3420 offline.
Disconnect interface connector at 3420.
Switch online/offline switch to "online".
Jumper proper TV bus-out bits (oIle at a time) to ground (D08 pin).
Scope each sense bit. (Ground Level =Bit On)
(+4.4V = Bit Off)

TAPE UNIT SENSE BYTES

~ SensoBit

Scope Points

L2D02

L2D04

L2D05

L2D06

L2D07

L2D09

L2D10

L2D11

Tie
to
D08

Byte

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

J11

Byte 0

Backward

Not File
Protect

EOT

BOT

Write Status

Start

Unit Check

Not Busy

Byte 1

7-Track

Write Current
Fail

Dual Density

Alternate
Density

Mod 4,6, or 8

011 = 75 ips
100 = 125 ips
101 = 200 ips

G09

Byte 2

Lamp Failure

Left Col
Failure

Right Col
Failure

Door Interlock
or Reset Key

Data Security
Erase

Erase Head
Failure

Air Bearing
Failure

Load Failure

G08

Byte 3

G07

Byte 4

G05

Byte 5

High-Order
Serial Number

EC Level of Tape Unit

Tape Present

Reels Loaded

G10

Mod 3, 5, 7
K4 Card
~-----1 (C) Check Kl Contactor for
Arcing.
(D) See Drop Ready and
Write Current (2nd and
3rd Blocks Below).
(E) 2A·000 Model 3, 5, 7
2B·000 Model 4, 6, 8
(E) 15-090

>;.::.-----1

No Bor WritelWTM
(A) Capstan Moved but Tape
Did Not, Tape Hesitated
or Stuck. Refer to
Service Aid 3.
(B) Badly Creased Edge of
Tape. May be a Tape
Handling Problem,
Mainly Shows up, if
Edge Crease, on WTM.
(C) Two Tracks Missing on
WTM, Develop Tape. .
(D) If Writing Short Records
and One is Placed With·
in a Crease, the Record
May Not Appear on Tape
Because of Lift Off Due
to the Crease.
(E) 5A·000 Model 3,5,7
5B·000 Model 4, 6, 8
(F) 16·190

(A) Dropped Ready While
Executing a Motion Type
Command.
.
2A·000 Model 3, 5, 7
2B·000 Model 4, 6, 8
(B) See Drop Ready Chart A
and B Attached.
(C) Reject TU Without TU
Check, Drop Busy on Re·
wind, Write Status on
During Rewind or Drop
Start on a Rewind.
(D) 15-090 and 15-100
(A) Write Card or Cable to
Write Card Loose."

>:..::::..-----1 (B) Tape Unit A 1G2 Model
4,6,8
(C) 15-090

>..;;.;;..-----1

Tach Start Failure
(A) Capstan Board
(B) Capstan Tach
(C) Capstan Motor
(D) Fiber Optics Bundle
(E) TU Cards· (See Step
"H" for FRUs).
(F) Check Service Aid 3,
Mainly for Model 3,
5,7
(G) Check Power Supply
Levels, Vacuum and
Air Bearing Pressure.
(H) 6A·000 Model 3, 5, 7
6B·000 Model 4, 6, 8
(I) 16-17

Velocity Check
(A) Excessive Drag in the
Tape Path, Such as Low
Air Bearing Pressure,
Loose Stubby Column
Bars (Low Vacuum in
Stubby Column).
(B) Tape Stick or Contamin·
ation Mainly Model 3, 5,
7, Refer to Service Aid 3.
Will Also Happen on
Model 4, 6, 8.
(C) 6A·000 Model 3, 5, 7
6B·000 Model 4, 6, 8
(0) 16·180

(A) See Drop Ready Chart
"A" and "B" (Attached).
(B) Drop Ready Test Points
on FTl14.
(C) 2A·000 Model 3, 5, 7
2B·000 Model 4, 6, 8

Sense Byte 10 Bits
Not in the Order of
Their Importance.
0=

Command Status Reject
(A)A1K4
(B) Reseat Cables from Tail·
gate to the B3 Board in
3803.
(C) Could be a Signal Line
Grounded to the Plated
Connector on the Cable
Going from the CU to
TU.
(D) 6A·160 Modell, 5, 7
5B·000 Model 4, 6, 8
(E) 15-020.16·160

[FE127604]

3803-2/3420-3 THROUGH 8 TAPE DRIVE SENSE ANALYSIS
(4 of 7) (continued)

(A) Losing a Track on WTM,
Usually Caused by Tape
Lift Off. Inspect R/W Head
and Tape_
(B) Read or Write Card.
(C) 5A-ooo,5B-000
(D) 17-180
(A) Tape Crease
(B) Oxide Dump or Contamination
(C) 5A-000 Model 3, 5, 7
5B-000 Model 4, 6, 8
(D) 17-080

6250/1600
Read

(A) Read Head Magnetized.
(B) Noise at Amplitude Strong
Enough to Indicate Bits Before
Actual Record has Reached the
Read Head, Defective Erase
Head.
(C) Read Card Not Seated.
(D) Check Columns and Glass
Cover for Air Leaks.
(E) 5A-000, 5B-000
(F) 17-170

(A) Primarily a 3803 Failure.
(B) 17-016 and 17-010

(A) Not Normally a Drive Problem_
(B) Hardware Triggers Out of Parity.
Ie) 17-026 and 17-020

(A) Excessive Drag or Tape Slipping,
Clean Capstan.
(B) A 1 K2 in Tape Drive.
(C) A1H2 in Tape Drive.
(D) Scope for Noise on Tach Busy
line at Tape Drive Interface.
(E) 17-600 and 16-180
[FE127603]

3803-2/3420-3 THROUGH 8 TAPE DRIVE SENSE ANALYSIS
(S of 7) (continued)

Heady Dirty - Track Lift Off.
A1J2 TU - Write Driver.
Read or Write Card.
Check Sense Byte 2 for Track.
RIW Head
5A-000 Model 3, 5,7
5B-000 Model 4, 6, 8
(G) 16-160

(A) Refer Also to R/W VRC.
(B) 17-110,17-310,17-112

(A)
(B)
(C)
(D)
(E)
(F)

Yes

(A) 17-190
Yes (B) Primarily a 3803 Probl~l!'.

(A) Look for Tape Damage or

Tape Contamination.
(B) 5B-000, 6B-000 Model 4,
6,8
5A-000, 6A-OOO Model 3,
5,7
(C) 17-070

(A) 17-530,17-540

(A) Generally Accompanied by
MTE, Envelope Check Being
Off Indicates No Drop Out
of Amp Sensors. Check
Read Card.
(B) Erase Head Not Erasing all
Tracks.
(C) 5A-000 Model 3, 5, 7
5B-000 Model 4, 6, 8
(D) 17-170

(A) Data Sensed During Erase
or Erase Portion of WTM.
Suspect Noise from Read
Card.
Yes (B) Defective Erase Head.
(C) If Accompanied by Other
Bits They will be the Most
Important.
(D) 17-370

(A) 1600 bpi WTM - Read Card.
(B) Not Able to Detect EOO.
(C) 5A-000 Model 3, 5, 7
5B-000 Model 4, 6, 8
(D) 17-150

(A) Check Byte 2 for Error
Track.
(B) Generally Caused by Lift
Off Due to Head Being
Dirty or Contaminated.
(C) A1J2 in TU - Write Driver.
(D) Read or Write Card, Ensure
They are Seated Properly.
(E) RIW Head.
(F) Write Card Transistor (5Track) Touching the Cartridge Motor.
(G) 5A-000 Model 3, 5, 7
5B-000 Model 4, 6, 8
(H) 17-220 17-310

[FE127605]

3803-2/3420-3 THROUGH 8 TAPE DRNE SENSE ANALYSIS
(6 of 7) (continued)

(A) With a High Rate of MTEs One
Track May be Bad All the Time,
(1600) Read Card.
(B) Contamination.
(C) Read or Write Card.
(D) R/W Head.
(E) 5A·000 Model 3, 5,7
5B·000 Model 4, 6, 8
(F) 17·110,17·310

(A) Track Other Than "1" or
"P", with Damaged or
Dirty Head.
(B) Scope Read Bus all Tracks.
(C) 58·000 Model 4,6,8
(D) 16·220
(A) Look for Bad Record on Tape.
(B) Glazed Capstan.
(C) Capstan Control Board.
(D) Capstan Motor.
(E) Creased Tape.
(F) Short Gaps Created by Tape
Slip During Write, Glazed
Capstan, or Tape Stick. Loss
of Vacuum on Capstan Model

(A) Primarily a 3803 Problem.
(B) 17·010, 17·530

(A) 1600 or 6250: Look for a
Weak Signal at the Trailing
End of the Record.
(B) Develop Tape and Look for
the Trailing Portion of the
Record to be Over Written.
(C) Crease or Contamination
Across Tape.
(D) 17·530

8.
(G) 6B·000, 6A·000
(H) 17·070
(A) Crease or Damage After Begin·
ing All Ones. Not Recognizing
End of Data.
(B) End of Record Overwritten (by
Write Heads) During Backspace
Rewrite Sequence. Tape Slip·
clean the Capstan.
(C) 6A·000, 6B·000
(D) 17·410

(A) 17·190
(B) Scope and Determine How
Many Bytes of Zeroes There
Are, if This is a Permanent
Error.
(C) 17·190

(A) Can Not Identify the Tracks to
Correct. Dirty Head Most
Likely.
(8) Check for Tape Damage and
Also Refer to MLM 00·011 and
00-012, Permanent Error
Section.
(C) Plastic Tach Cover Rubbing
Capstan.
(D) Check for ENV (Envelope) or
MTE on. 5A·QOO Model 3, 5, 7
5B·000 Model 4, 6, 8
(E) 17·170

(A) Noisy Read Card or A 1 K2
(6250)
(B) Noise Read Card or A 1J2
(1600)
(C) 17·150
(A) Turned on by any 6250/PE
Read or Read Backward Data
Check.
(B) When no Data is Transferred to
the Channel on a Read or Read
Backward Operation.
(C) 17·370

(A) Very Unlikely a Tape Drive
Problem Except in NRZI
Mode.
(B) 5A·000 Model 3,5,7
5B·000 Model 4, 6, 8
(C) 17·160

[FE127602]

3803-2/3420-3 THROUGH 8 TAPE DRIVE SENSE ANALYSIS
(7 of 7) (continued)

(A) 7-Track - "C" Compare is Set When
Combined Data "P" Does Not Match
Read Data Track "P".
(B) 17-010

(A) Low Amplitude During Write,
Check for Dirty Head or Edge
Damage, Such as Wavy 5 or 4
Track.
(B) Write Card or A1J2.
(C) Read Card
(D) Head Wear, Outside Track Flutter.
(E) 5A-000
(F) 17-310

(A) Data Detected During Read Stop
Delay, Check for Extra Bits on
Tape. May Have Been Poorly
Erased.
(B) 17-370

(A) Mechanical or Electrical Skew
Out of Specification.
(B) NRZI Guides Not Operating
Proper.
(C) NRZI Skew More Critical Than
1600 or 6250.
(D) 5A-OOD
(E) 17-160

(A) Tape Could Have Been Written
With the NRZI Guides Held Out
of the Tape Path by Some Foreign
Matter. This Allows the Tape to
be Written Skewed. Check Capstan Tracking.
(B) Edge Damage or Dirty Head.
(C) 5A-OOD
(D) 17-170

(A) 17-310

(A) Set When CRC Byte Calculated
on a Read Operation Does Not
Match the CRC Byte Written on
Tape (9·Track NRZI).
(B) Usually Accompanied by Read
VRC and LRC. If so, Shoot
Read VRC.
(C) 17-590

(A) See Sense Byte 9, Bit 3. Did
Not Read the Same CRC Character Combination That was Just
Written.
(B) 17-530 and 17-590

(A) If Accompanied by Read VRC
or CRC, Shoot Them First.
(B) 17-310

(A) Data Detected During Erase Gap
Operation or During Erase Portion of a WTM Operation. Check
for Proper Seating of Read and
Write Cards.
(B) Erase Head Not Erasing Properly.
(C) 5A-000 and 17-370

(A) 5A-000
(B) 17-170

[FE127606]

3420/3803 ONLINE TESTS
IBM 3420/3803 Online Tests, Listed by Section
Section

Test Focus

Test Mode

Test TYEe

A:
B:
C:
D:
E:
F:
G:
H:
I:

Control Unit
Control Unit
Control Unit
Control Unit
Subsystem
Control Unit
Control Unit
Control Unit
Control Unit
Control Unit
Control Unit
Tape Unit
Control Unit
Control Unit
Control Unit
Tape Unit
Subsystem
Subsystem
Control Unit
Subsystem
Tape Unit
Tape Unit
Tape Unit
Tape Unit
Control Unit
Tape Unit
Tape Unit
Tape Unit
Control Unit
Control Unit
Control Unit
Control Unit
Control Unit
Control Unit
Control Unit
Control Unit

PE/6250/NRZI
PE/6250/NRZI
PE and 6250
6250/1600/NRZI
PE/6250/NRZI
6250 Only
6250 Only
PE Only
PE Only
PE Only
PE Only
PE Only
NRZIOnly
NRZIOnly
NRZIOnly
NRZIOnly
PE/6250/NRZI
PE/6250/NRZI
3803-2
PE/6250/NRZI
PE/6250/NRZI
Pp/6250/NRZI
PE/6250/NRZI
PE/6250/NRZI
3803-2
PE/6250/NRZI
PE/NRZI
PE/6250
PE/6250/NRZI
PE/6250/NRZI
PE/6250/NRZI
PE/6250/NRZI
PE/6250/NRZI
PE/6250/NRZI
6250 Only
6250 Only

Diagnostic
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Reliability
Analysis
Reliability
Diagnostic
Diagnostic
Functional
Functional
Analysis
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Functional
Diagnostic
Diagnostic

J:
K:
L:
M:
N:

0:
P:
Q;
R:
RO:
S:
T:
U:
V:
W:

WR:

X:
Y:

Z:
AB:
AC:

AD:
AE:
AF:
AG:
BA:
BB:

CMD Sequence Analysis
Control Unit
Control Unit
Channel Buffer R/W & Mode Set
Basic Read and Write
6250 Data Path Verify
6250 Error Detect/Correct
PE Diagnostic Mode (Part 1)
PE Diagnostic Mode (Part 2)
PE Diagnostic Mode (Part 3)
PE Diagno,stic Mode (part 4)
Mod 4, 6, 8 Clip Level Check
NRZI Control Unit
NRZI Diagnostic Mode (Part 1)
NRZIDiagnostic Mode (Part 2)
7-Track Functional Tests
Long Record Write/RDB/Read
Write Reliability
MAPs Analysis
Read Reliability
Tach Parameters
Tach Asymmetry
Start/Stop
IBG and Creep
MAPs Analysis
Reel Response
Data Access Measure 1
Data Access Measure 2
Device Switching
Control Unit Status
2-Channel Switch (Part 1)
2-Channel Switch (part 2)
2-Channel Switch (Part 3)
2-Channel Switch (part 4)
Stress Tape 1
Stress Tape 2

3420/3803 ONLINE TESTS (continued)
Section RO-WR: Error Analysis
These two OLTs apply to the 3803-2 only. The MAPs and the OLTs are designed as an
integrated package. You should start with the MAPs and run the OLTs as indicated when
analyzing an error.
All of the 3803-3420 OLTs diagnostics can save the error sense data for later analysis by
OLT 3420RO and OLT 3420WR. The error sense data "save" field is: a common area for
all of the 3803-3420 OLTs. Therefore, if more than one OLT is run and has errors, the
sense data from the last error in the last OLT run is available for analysis.
Although the sense data is saved for an error in all of the OLTs, only OLTs A-G, P, Q, R,
and S are recommended for FRU analysis. The sense data from the other OLTs can be
analyzed, but the results may be misleading. This is due to errors that are forced by the
OLTs.
OLT WR has an EXT= option whereby sense data to be analyzed can be entered from
the keyboard.
Example:

DEV j3420WRjEXT= ,SNS=804400

8000002C000008000000C7j
At least the first fourteen bytes (0-13) should be entered. The extent field (EXT=) however, will not permit entry of all 24 bytes.

How to Generate a 'Prewritten' or 'Read Only' Tape
In MAPs, you will note references to a 'Read Only' tape. (In several sections of the User's
Guide, you will note references to a 'prewritten tape'. The terms 'prewritten' and 'read
only' are synonymous.) This tape is a diagnostic tool which should be generated when
the system is operating correctly. You should have a 'Read Only' tape generated in 6250
bpi available for analyzing failures. Sense switch Z which is in OLTs routines A-G generates 'Read Only' data in 6250 bpi.
Note:

When changing the EXT= parameter, the program must always be called:
Example:
Example:

DEVj3420A-GjEXT=Zj
j3420A-ZjEXT=WZj
not j jEXT=Zj.

3420/3803 ONLINE TESTS (continued)
To generate a 'Read Only' tape (6250 bpi), the OLTs A-G are run with first error option
and sense switch Z on.
Example:

DEVj3420A-GjFE,EXT=Zj.

When the 'Read Only' tape has been generated without any errors, the tape should be
file protected.

False Crease Tape Error - OLTOLT

Messages

T3420I

AIOI08

T3420L

AI0137

T3420K

AKOI06

T3420M

AMOI08

If byte 17 (EC) is not plugged correctly on logic AA004.
Prior to EC733843 bit 6 and 7 should be 01
After
EC733843 bit 6 and 7 should be 10
After
EC734866 bit 6 and 7 should be 11
R060 OLTs reversed test I and M.
If byte 17 is plugged incorrectly the wrong routine will be run.
This is for a 3803 ModOOl only. A 3803 Mod002 will be plugged for bit 6 and 7 = 01.

Stress Tape PjN1848621
A prewritten tape used for diagnosing the operating parameters of the 3803 Mod 2 has been
been generated by a unique machine for this purpose and cannot be created or duplicated
by any other known method. This tape is used in conjunction with OLT diagnostic
T3420BA and T3420BB (stress tape 1 and stress tape 2) and should be ordered from the
nearest EPC just prior to converting a 3803 Modell to a Model 2. Reference OLT User's
Guide dated March 1974 or later for explanation of tests etc. After the tape has been
used to check out the converted units the tape is to be returned to its original stocking
location for use by other conversion sites. The tape is not intended to be kept at the
branch office or customer location. The reason for this is that there are only a limited
number of these tapes available. As recertification of the stressed data is not possible,
care must be exercised so as not to damage the tape. A damaged tape will have to be replaced with a new one.
The recommended stocking level is three tapes at each emergency parts center (EPC).

WHAT IS WHERE IN THE MLM?
MLMVolume 1

Section

Contents

PLAN

Safety information; table of contents (organization of publication), a list
of abbreviations and symbols and the address for ordering the OLTs
User's Guide.

Notes on how to use the MAPs effectively; training requirements for using
the MAPs effectively, method of identifying ECs which affect the MAPs,
standard plus and minus voltage levels encountered ;in the machines,
sense byte chart with references to descriptions, a symptom index (page
0-010) for normal entry into the MAPs, a quick index (page 0-009) for
entry into the MAPs when you have one of the symptoms listed there
and you know whether the problem is in the TU or TCU.

IA-6A

MAPs for 3420 Models 3, 5, and 7 attached to 3803-2. (Same as Pathfinder for these models attached to 3803-1.)

IB-6B

MAPs for 3420 Models 4, 6, and 8. Note that Section I B follows Section
6A,not IA.
Sections 1 through 6 (both A and B) contain MAPs for TU power supply,
thread/load, basic motion, unload, read/write and capstan motion control
problems, in that order.

WHAT IS WHERE IN THE MLM? (continued)
:MLM Volume 2
Section

Contents

TV interface theory

Checks, adjustments, removals and replacements

Tev power supply MAPs

Procedures for duplicating failures offline and procedures for performing
various CE panel functions (extracting sense data, restart on ALV error,
etc.)

MAP procedures for ALV hangs or loops, channel busy, timeout, or other
indications where the microprogram does not appear to be looping normally (possibly also causing channel hang).

Manual analysis of sense data using a prioritized scheme.

MAP procedures for miscellaneous errors.

WHAT IS WHERE IN THE MLM? (continued)
MLMVolume 3
Section

Contents

MAP procedures for equipment checks

MAP procedures for data checks, including timing charts of various data
operations plus second levels of the conditions required to produce the
error.

Device switch theory and MAPs for problems isolated to the device switch.

Board layouts for the TCU and TU boards showing the functions performed for each card to assist in card swapping.

Logic net cross-reference list. The MAP scoping procedures allow you to
identify a failing line and the FRU from which this line originates. If
replacing that FRU does not correct the problem, you may suspect a loading problem at the other end of the line (net). This cross-reference list
provides the references to logic for all line (net) names encountered in the
MAPs so that you may more easily pursue problems of this nature.

OLTEP error message analysis. Used as directed by sense analysis sections
3420RO and WR after certain errors encountered by sections 3420 F and

WHAT IS WHERE IN THE MLM? (continued)
MLM Volume 4
Section

Contents

Subsystem characteristics, features, etc.

TCV data flow, MPI/MP2 schematic, ROSI trap conditions 6250 read/
write service requirements.

Microprocessor theory

TCV oscillators, clocks, counters and controls, second levels and theory

TV selection and priority

Loop write to read (LWR) purpose, operation and data flow

NRZI data flow and theory

Two-channel switch and device switch theory

CE panel- description of switches and indicators

Tools and test equipment

Subsystem preventive maintenance

Subsystem installation procedures

Index

COMMON ABENDS
Reference MLM 00-035

Abends-Theory
Abend 137,237,413,613, and 637 may be caused by missing tape marks.
Missing tape marks are caused by:
• Incorrect forward-backward ratio.
• Loss of signal amplitude causing a failure to recognize the tape mark.
• Excessive crosstalk, indicating that data is fed into a dead zone. Data recorded on any
track in a dead zone. will prevent reading a tape mark correctly.
To check for loss of amplitude and crosstalk use the failing drive and tape. Find the tapemark on the tape that was not read correctly. Cycle back and forth across the failing tape
mark with the CE panel. Sync on Go Forward (T-AIF2J10) and scope all tracks (read
card test points) and ensure that the signal is good on all tracks in zones 1 and 2 (tracks
P, 0, 5, and 2,6, 7).
Measure the amplitude on tracks 1, 3, and 4 (zone 3) and ensure that there is less than
140 mv of signal (Models 4, 6, and 8 only).
Crosstalk is caused by:
•

Defective write card.

• Defective read card.
• Defective R/W head.
• Poor tracking. If tracking is out of specifications go to Capstan Dynamic Alignment
(see 08-150). The drive that wrote or read the tape, or both, could cause crosstalk.

If the failing tape is not available, write a tape on a working tape drive offline, and use
that tape to check for crosstalk on the suspected failing drive.
137/637 Abend
Machine
Type

Possible Causes

3803

Defective 01 A-A2N2 card

, 3803

Defective 01 A-B2F2

COMMON ABENDS (continued)
237 Abend
Machine
Type

Possible Causes

3420

Large tape creases detected as gaps (check stubby
bar clearance).

3420

Short records (80 characters) falling within a tape
crease.

3420

Tape edge damage.

3420

E/C 443935 (6250) - Fix for short gap verification
during backspace after a write error caused by
erratic tape motion, not installed.

3420

R/W head forward-to-backward ratio is out of
specifications.

3420

Tape sticking.

3420

Dirty capstan.

3803

Missing Suppress Out, intermittently breaking
channel/command word (CCW) chain, updating
the count but not losing a record.

3803

Defective 01 A-B3F2 inbound tag card XC700.

3803

ECA079 - Unexpected interrupt with status

= '00' from a non-two channel switch in multiple
CPU 2X, 3X, 4X, installation.

COMMON ABENDS (continued)
413 Abend
Machine
Type

Possible Causes

3420

Defective T-A 1C2 MST card.

3420

Reading 6250 tape in 1600 mode.
E/C 443890 - Autocleaner sluggish,
not installed.

3420

Defective A1 H2

3420

. Defective T-A 1 L2

3420
Models
4,6,8

E/C 735817 - Delay Ready after rewind,
to allow autocleaner to return, is not installed.

3420

Damaged tape at load point.

3420

Contamination on the Read/Write head, or the
capstan is glazed.

3803

Defective 01 A-A2D2 MST card or defective
01A-A2E2 MST card.

3803

Broken CCW chain without Unit Check. Run
an I/O software trace for more problem definition.

3803

ECA079 - Prevent busy in middle of CCW chain,
not installed.

3803

ROS patch to ALU1 for allocated busy is not installed.

COMMON ABENDS (continued)
613 Abend
Machine
Type

Possible Causes

3420

E/C 443935 - Short gap engineering change not
installed.

3420
Models
4,6,8

ECA073 - Delay Ready after rewind to allow
autocleaner to return, is not installed.

3420

Contaminated Read/Write head.

3420

Damaged tape at or near load point

3420

Read/Write head forward-to-backward ratio
not in specifications.

3803

Defective 01 A-A2N2 card, extra tape mark.
Defective 3168/2880 card, high-speed buffer
data compare.

OS/VS2
R017

PTF 70751 not installed.

3803-1

Tape Tracking, leaves a faint TM (where
existing files are updated) because of the
overwriting of the old EOF TM. In this
case the writeheads actually do the erasing
of the old TM.

3803-1

Defective 01 A-B2F2

3803

Incorrect UCW Plugging

Compatibility problems between drives can be caused by tracking out of adjustment,
or if this adjustment is OK, the tracks are not centered on tape. Develop tape and
place it on the viewerto observe. The proper positioning of the head to tape relationship is done by the Skew Plate. A special Skew Plate adjusting tool is necessary to do
this {included in the Reference Plate replacement kit, BM 4298806 stocked at the
(EPC's) E level parts centers}. Reference SA 9 and SA 10.

TOOLS AND TEST EQUIPMENT
The tools and test equipment listed in this section are required to properly service 3420
Magnetic Tape Units and 3803 Tape Controls.

Kept at the Regional Office
Part

Name

8216729
8218343

ROS Address Tracer
Variable Frequency Oscillator (VFO)

Kept at the Branch Office
Part

451064
453522
453585
4169639
2515376
2515390
2515401
2523723
5861448
5861455
5861452
8215414

Name
Master Signal Level Tape (see Notes 1 and 4)
Degausser (see Note 1)
Developing Solution
*Digtec 251 Meter (Digitec 201 Meter, PIN 453046, may be used if it is available)
Scale, 0 to 6 pounds (belt adjustment)
Capstan Prealignment Gauge
Capstan Adjustment Wrench (rear adjustments)
Reel Motor and Hub Adjustment Tools (see 08-460)
Capstan Adjustment Wrench (front adjustments)
7-Track NRZI Threshold Adjustment Card
PE Threshold Adjustment Card
Dual Density Threshold Adjustment Card
ROS Patch Card (see Note 1)

Kept at EPCs
Part

Name

4298806
1848621

Reference/Skew Plate Replacement Tool Kit (Ref SA-9 and SA-l 0)
6250 BPI Stress Tape (see Note 3)

*Trademark of United Systems Corporation

TOOLS AND TEST EQUIPMENT (continued)
Kept at the Customer's Account
Part

Name

8493001

Tape Transport Cleaner
Scratch Tape
Oscilloscope (Model 453, 454, 561, 545, 766H or equivalent)
Tape Cleaning Kit
Master Skew Tape (see Notes 1 and 4)
Manometer 30 inch (two needed for series connection) (See Notes 1
and 2)
Tee and Hose Assembly (see Note 2)
Tape Development Solution
Tape Unit Tester
Shim, Right Reel Hub Adjustment
Hex Wrench, Right Reel Hub
Adapter Hose (see Note 2)
Pressure Divider (see Note 2)
Tape Unit Cleaning Brush
Crimper (supplied by marketing representative)
Capstan Box. Wrench (rear adjusting capstan only)

352465
453500
453504
453522
1765342
1846251
1846252
2515745
2513154
2501611
2512063
2515390

Notes:
1. Discussed in more detail in the MLM
2. Not needed if pressure/vacuum gauge PIN 5495384 is available
3. 1848621 stress tape used for model conversions stocked at EPCs. See
Also see page 29 for description.
4. Order through IRD per the "Order Processing" section of the IRD Branch
Office Manual.

TOOLS AND TEST EQUIPMENT (continued)
Master Tapes
Master skew tapes and master signal-level tapes are manufactured to rigid specifications.
They are the standards that are used by CEs to obtain optimum tape unit performance.
Because tape unit performance is directly affected by the accuracy of these master tapes,
the following precautions should be taken~
1,
2.
3.
4.

Use master tapes only for their intended purpose.
Handle tapes with care.
Make only full-reel passes in order to have even wear throughout the length of the tape.
Identify master tapes as such and mark the reels with the letter "m," as a reminder to
make full passes only.

Master Skew Tapes
Master skew tapes have a density of 800 fci and are written with one solid bit across the
width of the tape. These tapes are written on a specially adapted tape unit at the Tape
Test Center with accuracy held to within 0.375 usec total skew between the leading and
lagging bits of a 112 ips tape unit.
The master skew tape will run off the reel when reading forward because it is written
with no interblock gaps (IBGs). In order to create an IBG and save time during skew
adjustments, make the follOwing alterations to the master skew tape:
1.
2.
3.
4.
5.

Read the master skew tape forward to the end of tape (EOT) reflective marker.
Install a write enable ring.
Write one record of any size beyond the EOT marker.
Remove the wr~te enable ring.
Rewind the tape.

After the preceding one-time preparatory steps, set the tape control CE panel as follows
when you use the skew tape:

1. Command I-Read Forward ('02')
2. Command 2-Read Backward ('~C')
3. Command 3-Read Forward ('02')
4. Command 4-Read Backward ('OC')
The master skew tape will read forward to the end of the reel, read backward, and repeat
the cycle. This permits checking skew from the rear of the tape unit without manipulating the controls.

TOOLS AND TEST EQUIPMENT (continued)
Master Signal-Level Tapes
Master signal-level tapes have the ability to produce a signal to within ±2% of the primary
master. (A primary master, which is established as an IBM standard, is the base for instrument alignment.)
All new master signal-level tapes are checked at 3200 fei and 800 fci. The suffix letter
"A" is added to the part number to allow field identification of 3200/800/556 fei tapes
as opposed to the former 800/556 fei tapes. Thus, for example, a master Signal-level tape
checked out at both 3200 fei and 800 fei would have PIN 432152A.

Degausser
CAUTION:

Do not use the degausser near magnetic tape of any kind because it erases
the information on tape. Power-down the tape unit.

To degauss the read/write head:
1. Remove magnetic tape from the tape unit. Do not place the tape on top of the tape
unit.
2. Plug degausser into 110 Vac receptable.
3. Press the pushbutton on the degausser while it is at least one foot (30,5 cm) away
from the read/write head and move it slowly toward the head.
4. Hold the degausser agai~st the front surface of the head for about ten seconds.
5. Pull the degausser straight away from the head very slowly to a distance of at least
one foot (30,5 cm) and release the pushbutton.

MST Board Ordering
Instructions for ordering a 3803 MST board for field replacement. The following information must be supplied when placing the order.
1.
2.
3.
4.
5.
6.
7.

Machirie type and serial number
Features on the 3803
Part number of the MST board
EC level of the board
REAs installed (if any)
Board location (example - B3)
Name and phone number of person to contact in case the plant needs further information. Note: There are some 3803 boards with EC733806 written on the sticker. This
is a non-existent EC number. The EC number should be EC733801.

TOOLS AND TEST EQUIPMENT (continued)
8. Refer to AA005 in the logics for feature wiring before installing the board. (five pages
3803-2 and three pages 3803-1)
9. Have sufficient quantities of resistors on hand. See part numbers below.
3803 MST Flat Cable Replacement - see General CEM 251.
3420 MST Flat Cables Replacement:
PIN 5802133 uses PIN 580218048 in.
PIN 5802181 64 in.
PIN 5802134 uses PIN 5802182 48 in.
PIN 5802183 64 in.
3803 Tie UplDown Resistors:
PIN
Wire Color
2520936
2520942

Tie-Up
Blue
Tie-Down Yellow

Resistance

Tie to Pin

51n
620n

D08
B06

MEDIA

IRD PEP SPECIALIST
If you have reason to believe the customer's tape library contains tapes of poor
quality or if you need expert assistance in finding methods of locating bad tapes then
consider contacting your IRD PEP Specialist.
The PEP (performance Evaluation Program) Specialist is a person expertly trained in all
phases of magnetic tape evaluation. He can provide assistance in most any area relating
to media problems and should be a useful resource for the CEo
Your field manager should be consulted before involving the PEP specialist.

MAGNETIC TAPE
Most of the recording media in today's digital record environment is a polyethylene
terephthalate film, (mylar*), coated on one side with a flexible thin layer of ferro-magnetic material. The tape is slit to .498 ± .002" wide and reflective stickers are mounted
at each end to mark the beginning and end of the usable area of tape. Tapes come in
two standard lengths - 1200 and 2400 feet.

Under normal operating conditions tape should operate at least 40,000 passes before a
permanent read error is encountered. This is possible only when tape is stored in the
proper environment and handled properly when in use.
Tape can deteriorate due to conditions encountered in storage, handling, or operating on
drives. This degradation will show up as an increasing number of temporary write or read
errors during its use until the damage gets extensive enough to cause a permanent error.
When storing tape it should be stored in an area where the temperature is between 40
degrees to 90 degrees F (4 degrees to 32 degrees C) and 20 to 80 percent relative humidity (nominally 70 degrees F at 35 percent relative humidity). To operate, tape should
be at 60 degrees to 90 degrees F (16 degrees to 32 degrees C) and 20 to 80 percent
relative humidity (nominally 75 degrees F at 45 to 50 percent relative humidity). When
tape is exposed to temperatures in excess of the above criteria degraded operations may
occur. Tape should be acclimated to the operating temperature for at least 24 hours
before use if large environmental changes are encountered in storage or use.
When a reel of tape exceeds a specified number of errors it is recommended the tape be
removed from service. The specified number will vary from customer to customer. It is
dependent on several parameters of this total system operation.
Details of tape properties essential for IBM tape units are found in IBM manual,
\GA32-0006, tape specifications for IBM one-half inch tape units at: 556,800,1600,
and 6250 bpi.
*Trademark of E. L du Pont de Nemours & Co. (Inc)

MAGNETIC TAPE (continued)
Tape Quality
Reference GA32-0006, Tape Specifications for IBM One-Half Tape Units.
These paragraphs have been added to provide IBM's recommendations as to what quality
a tape should contain when new (paragraphs 1 and 2) and as it exists in the library (paragraph 3).
1.

Sho_rt-Length Reliability
Definition - J'he ability of the tape to withstand the wearing action encountered
during repeated references to a short file of data.
Recommendation - Under the conditions of the follOwing test procedure the tape
should average at least 40,000 read passes before a permanent error is encountered.
Procedure - Write a length of tape from load point with ten, 2000-character records (PE recording). No write skips shall be allowed during the write pass. Then
read the ten records (read forward/rewind) repeatedly until a permanent read error
occurs. Perform this test with sufficient go-down time (20.0 milliseconds) to ensure that the tape comes to a complete stop for each record.

Long-Length Durability
Definition - The ability of the tape to resist the wearing action encountered while
cycling full length on a tape unit. This is not a test for end of life.

MAGNETIC TAPE (continued)
Recommendation - At least 90 percent of the tapes tested should meet the following criteria:

Tapes tested for use at 3200 fci should not average more than three write errors
per pass, or exceed ten write errors on any single pass, for a minimum of 200 forward passes on any IBM tape unit that operates at 3200 fci.
Procedure - Use the appropriate tape unit and associated tape control for this test.
Write a 2400-foot (732m) length of tape in start/stop mode with 2000-character
records (PE recording) on each pass. In order to determine the effect of wear particles generated during the test do not clean the tape unit between passes.

library Quality
Definition - A measurement of the quality of tape is its write ca pabiltiy.
Recommendation - Tapes with more than twenty write skips are not recommended.
If tapes of this type are used, more frequent cleaning is recommended.
Procedure - Use the appropriate tape unit and associated tape control for this test.
Write a 2400-foot (732m) length of tape in a start/stop mode with an average block
length of 1.5 inches (38.1 mm). By use of Volume Error Statistics, a measure of
the quality of the tapes and library can be determined. Volume Error Statistics are
available in the IBM Operating Systems, OS, DOS, and VS.

COMMON MEDIA RELATED PROBLEMS
Unevenness of Tape Wind (Staggered Wraps)
3420/3803 Service Aid 4
The manner in which a tape stacks on a reel when rewound is a product of three factors:
The drive, the tape, and the reel. These all contribute: however, in an individual case, any
one of these may be predominant. Some items that are pertinent to this matter are:
1.

Some irregularity of wind is to be expected. It is caused by aerodynamics (escaping air forming a cushion between layers), and static electricity which will attract
or repel the tape to or from a flange in varying degrees as the tape is wound.

A perfectly smooth wind (from a 3420 drive) is not necessarily desireable as it
tends to indicate the tape is being forced against one of the flanges or other guiding
surfaces.

If the wind is irregular, no damage to the tape will result unless poor handling
practices are followed; ie, pressure applied to the reel flanges causing a tape edge to
be bent over. This may be due to improper stacking of multiple reels not in containers or cartridges designed to be stacked or squeezing the flanges while handling
or mounting a tape.

The flanges of the reel are not designed to guide the tape or help it wind smoothly.
The flanges are there only to protect the tape during shipping and handling, and
then only to protect it from something bumping the tape edges, not from pressures
of such force as to bend the flanges.

Devices can be developed which will wind the tape smooth. You will note new tapes received by customers have a smooth wind. The field situation does not warrant installing
and maintaining such a device on field drives.
With each complaint or concern of staggered wraps, the best approach to the problem is
to adjust the drives as accurately as possible, so they are not producing ~nnecessarily
poor winds. Inspect the drives for any possible condition that may indicate wear or interference in the tape path. After it has been determined that the mechanical alignment of
the transport is acceptable, the customer should be instructed on proper handling
techniques for magnetic tape.

COMMON MEDIA RELATED PROBLEMS (continued)
Z-Folds
Loose wraps are usually caused by poor handling or poor leader on tape. When tape is
loaded on machine the loose outer wraps are pulled tight against loose wraps further in
causing Z-fold.
Z-folds can be avoided by adequate customer controls in tape handling, properly crimping end of tape, and library management. Also, beware of poor temperature control and
drives with different rewind tensions.
The IRD representative can provide a complete seminar which provides a comprehensive approach to all areas of magnetic tape care and handling.

3420

READ/WRITE SERVICE TECHNIQUES
Temporary jPermanent Errors

The primary cause of write data checks is the type caused by a loss in signal from the tape
on readback during write. On the 3420 tape subsystem when tape is written the amplitUde\s checked to ensure there is sufficient amplitude written on tape to be read at a
later date. This write checking level (threshold) is higher than the threshold at which the
tapes will eventually be read. If the amplitude of the read signal goes below the threshold
a temporary write error occurs and the error recovery program (ERP) takes control.
ERP backs the tape up to the last gap, then performs an erase gap before retrying the
write operation. If the write is then error-free one temporary write error is logged and
normal operation continues. If the retried write operation again fails another erase gap
then write is performed. This is continued until the write is successful or until fourteen
tries to write the record have occurred. In that event one loop write-to-read command
is tried. If successful, one more erase gap, write is attempted. If it again fails (fifteenth
time) a permanent write error is posted (the temporary write errors associated with this
failure are then discarded).
If the write command is successful on, for instance, try number 10 EREP would show
nine erase gaps (actual number) but only one temporary write error. The reason for this
is that write errors occurring while ERP has control are not logged to EREP while all
erase gaps are.
Several causes of data check on tapes are:
1.
2.
3.
4.
5.
6.

Defects in oxide on tape
Dirty tape
Dirty tape path
Edge damage on tape
Contamination on head
Tape device failures

When excessive e~rors are encountered on a tape, corrective action should be taken. The
first action would be to inspect the tape path for contamination. If any foreign material
is present, it should be removed by using normal cleaning procedures. If error persists the
tape should be tried on a second tape device (if available) or a different, known good, tape
should be put on the failing tape unit. In this way the error condition can be isolated to
the tape or to the tape unit. When a tape with large numbers of errors is found in a customer library it should be identified and corrective action by customer should be taken.
This can include cleaning and recertification of the tape or removing the tape from the
tape library. If a tape shows signs of damage or contamination it should be removed before it can cause damage to, or cause contamination to, other tape in the customer's
library.
There are many other types of errors and causes of errors. The several covered in the
above text are the most common causes and are the majority of the types of errors the
CE will encounter in the. field.

3420 READ/WRITE SERVICE TECHNIQUES (continued)
Read Amplitude Adjustment (Amp Sensors)

.Read amplitudes are adjusted prior to shipment. They should normally be readjusted
only if the read/write head or the read card is replaced. Before performing the adjustment procedure: (MLM ref 08-310, 46-8, or 08-290, 3-5-7)
1.

Ensure that the -4Vdc and +6 V dc supplies are correctly adjusted before adjusting the read amplitudes. (See 08-570, DC Power Supply Checks/Adjustments.)

Clean the read/write head and tape path before making adjustments.

Tape Slipping

Tape slip usually occurs during dynamic reversal while performing an erase gap command. Tape slip causes the tape to be incorrectly positioned. When the write head
becomes active it then erases part of the previous record. (The record before the
error record that the erase gap command was supposed to erase.)
Developing the tape shows the postamble missing on the previous record. For details
see Tape Developing Procedure in 3420/3803 Reference Guide.
FEraSedGap

~IIIIIIIIIIIIIIIIIIIIIIIIILr
t
t

Itl

I J

Load Point

!lllllllllllllllllllllllllllllllllllf

Erased Record

L- Erased Postamble and Part of
Data on Good Record

Possible Causes of Tape Slip:
a.
b.
c.
d.
e.
f.
g.
h.
Note:

Loss of capstan vacuum on Model 8
Drag in the tape path.
Dirty air bearings.
Low air pressure.
High or low vacuum.
Door glass leakage.
Damaged capstan surface.
Possible media problem.
Refer to 3420 Tape Motion section as well for tape slip problems.

3420 READ/WRITE SERVICE TECHNIQUES (continued)
Noise or Bits in the Interblock Gap
To detect interblock gap errors, sync scope on - Go Forward. Read forward and backward over the failing record. Display the record in both directions and look for noise
in the gap (see diagrams on MLM SA-lIS and SB-02S). Developing the tape with noise
in the interblock gap shows bits written in the area between two records (sometimes
faintly recorded).
Record

Record

.,~1~I O I IlIlIlI I lIlI~1I1I1 t ~I I I I I I I I I I I I I I I I ~I I I I I I
I

Load Point

Record

1~llllllt

Faint Line Approximately
.050, (1.3 mm) After End of
Record.

Possible Causes:
a.
b.

Gaussed or magnetized read/write head.
Erase head not working.

Bit Packing
Bit packing is due to varying capstan speed or tape slipping. For scoping procedure
see MLM SA-lIS or SB-02S. Also see 3420 Tape Motion Service Techniques.
Possible Causes of Bit Packing:
a.
b.
c.
d.
e'.
f.
g.

Tape slip when written (glazed capstan).
Dented capstan.
Vacuum and air pressure out of specification.
Plugged air bearing.
Improper operation of digital to analog converter (DAC).
Defective capstan control board.
Binds in capstan motor.

3420 READ/WRITE SERVICE TECHNIQUES (continued)
Tape Edge Damage
Scope the outside tracks (4 and 5 on 9-track drives) or (P and 7 on 7 -track drives) on
the failing record. Look at the amplitude changes.
Developing the tape will show bits that were recorded on the tape and the tape was
damaged after it was written. This type of damage is usually caused by improper tape
handling.
Example:

The tape reel has uneven wraps and the sides of the reel are squeezed
creasing the tape.

Read Forward to Backward Ratio Test (Models 3, S, 7)
Use this test to determine if a read/write head needs replacement.
Verify that the tape is tracking correctly before any head replacement because of the
above criteria. Perform Field Tester Accuracy Check on 08-290 before proceeding.
1.

Degauss the head (08-280) and the cleaner blade (08-390).

Obtain a customer good quality representative tape and write it at 1600 bpi on
the unit being checked. Write it from the field tester with frequency switch set
to 32.

Read forward to the middle of the reel of tape and stop tape.

Set the Field tester as follows.
ALTDIR
SLOW
READ
UP/FWD DN/BKWD. Potentiometers all the way to the back of tester.
(Adjust DN/BKWD so tape has a forward creep rather than a backward
creep).

Sync and scope the Read card test points to determine the fwd to bkwd ratio.
Display three or four cycles of read signal and use as much of the scope display
as possible for measurements (.2v/cm). For ease of recording, scope J2B13 with
another probe, this line will go positive when reading backwards.

If there is a read backward problem, and the amplitude in the backward direction
is less than that of the forward direction by 50% on anyone track, or 60% on the
remaining tracks, the read/write head should be replaced. If head replacement is
required, perform the removal/replacement procedure on 08-250.

3420 READ/WRITE SERVICE TECHNIQUES (continued)
Read Forward/Backward Ratio Test (Tape Unit Models 4, 6, and 8)
Use this test to determine if a read/write head needs replacement:
Verify that the tape is tracking correctly before any head replacement because of the
above criteria.
Perform Field Accuracy check on 08-315 before proceeding.

Degauss the head (08-280) and the cleaner blade (08-390).

Install a jumper from K2P02-M2D06. This forces 6250 mode.

Obtain a customer good quality representative tape and write it at 6250 pbi on
the unit being checked. Write it from the field tester with the frequency switch
set at 64.

Read forward to the middle of the tape and remove jumper K2P02-M2D06 while
tape is moving, then stop tape.

Set the Field tester as follows.
ALT DIRE
SLOW
READ
UP/FWD DN/BKWD Potentiometers all the way to the back of tester.
(Adjust DN/BKWD so tape has a forward creep rather than a backward creep).

Sync and scope the Read card test points to determine the fwd to bkwd ratio.
Display three Dr four cycles of read signal and use as much of the scope display
as possible for measurements (.2v/cm). For ease or recording, scope H2M08 with
another probe, this line will go negative when reading backwards.

If there is a read backward problem, and the amplitude in one direction is more
than double the amplitude in the opposite direction on anyone track, replace the
read/write head. If read/write head replacement is required, perform the removal/
replacement procedure on 08-250, do required adjustments and return to the map
that sent you here or 00-030. If replacement is not required return to the map that
sent you here or 00-030.

Note:

If while making measurements, the tape gets back to load point, (resetting the
6250 latch) the jumper K2P02-M2D06 will have to be reinstalled while at load
point and the tape read forward. This keeps the tape unit in 6250 without
forcing a SAGC setup on every record. Remove the jumper and continue the
test.

Each time the jumper is removed the SAGC may set up at a different ratio, but the ratio
will remain the same.
57

3420 READ/WRITE ~ERVICE TECHNIQUES (continued)
Phase Shift
Definition - A pulse time displacement that occurs at the transition from a low density
recorded signal to a higher density, or from a high density signal to a lower density.
When recording at higher densities several problems are encountered. As density increases the preceding and following bits (flux fields) tend to interfere with the middle
bit (see Figure 1). This phenomenon is known as phase shift. The resultant data transition at a change in recording density is shifted to the right or left because of the bit
crowding effect. This characteristic of PE recording is compensated for by detection
techniques.

",\

\
\

\ , "/

2X
Shift

Figure 1

3420 READ/WRITE SERVICE TECHNIQUES (continued)
Phase Shift Scoping Procedure
If you are having a high number of temporary write errors with MTE and not ENV
errors, use the following procedure to determine if the R/W head is causing phase

Using a good customer tape:
1.

Check the SAGC setup. Refer to the MLM page 5B-000 sequence 1.2 and 2A
with Figure A on page 5B-001. The SAGC should set up in 2 to 14 steps.

Loop write reliability test 3420R in 6250 mode.

Scope the phase pointers:

CD191
CD291
CD391

Card

Pins

YIM2
YIL2
YIK2

GI2,J11,112
G12, J11, 112
GI2,J11,JI2

Zone 1
Zone 2
Zone 3

Sync Points: Crosspoint cards can be used so that only data from the drive you are
running OLTs on is displayed (ie, logic XC701 drive 0 A3Q2 DI2). Refer to Chart L
for your machine configuration. If you have the entire subsystem, sync point (mark 1)
logic BW151 Al G3 M12 may be used.
If any phase pointer goes active, in the data area, the head is marginal. This procedure
is intended to find new heads"that may be marginal but should be used as a check for
existing heads. Refer to MLM 08-250 for additional information.

Compatibility
Compatibility problems between drives can be caused by tracking out of adjustment,
or if this adjustment is OK, the tracks are not centered on tape. Develop tape and
place it on the viewer to observe. The proper positioning of the head to tape relationship is done by the Skew Plate. A special Skew Plate adjusting tool is necessary to do
this (included in the Reference Plate replacement kit, BM 4298806 stocked at EPCs.
Refer to SA-9 and SA-l 0).

READ/WRITE FAILURE ANALYSIS
The purpose of this procedure is to provide an effective way to determine what R/W
component is failing. The procedure is comprised of three major sections. Initial
checks, failure analysis and FRU replacement. This procedure should help you reduce
the number of components replaced before fixing the machine.
Initial Checks
Check and adjust as necessary the following:
• -4 and +6 volts (see 08-570)
• Vacuum and pressure (see 08-400,08-405)
• Tape path obstructions
Check the following components for wear or oxide buildup.
-

Erase head
Filler block
Auto cleaner
Tape path area

• Clean the head
• Read head card and write head card seating

Failure Analysis
• Sense Data - Sense can be obtained from the following areas:
- EREP
Console messages
- OLTs
The sense data can be analyzed using the sense analysis flowchart in this manual.
• OLTs - Tests A-W should be run using a good test tape. If no failures occur use
the customer's failing tape, also try another tape drive.
• Scoping - The following items should be scoped to determine failing components.
Stability - Scope the analog signals on each track, the amplitudes should be constant and about equal between tracks.
Forward to Backward Ratio - The analog signal amplitude in any track while reading backward should not be less than 50% of the signal amplitude reading forward.
_Only replace the head if experiencing read backward problems.

READ/WRITE FAILURE ANALYSIS (continued)
SAGe - All tracks should set up between 2 and 14 steps and the tracks should set
up within 3 steps of each other. Replace the head only if the track setting up wrong
is causing errors.
Phase Errors - Phase errors are indicated by MTE errors without envelope checks.
Scoping is done in the 3803 while writing ripple data with a block length of 2K
or larger. This procedure is for model 4, 6, or 8 only. Refer to the phase shift
scoping procedure in this manual for complete details.
Tracking Check - Using the master skew tape scope the 4 and 5-tracks. The signals
should be equal and opposite between forward and backward. For example if track
4 leads track 5 by one usec in the forward direction, track 4 should lag track 5 in
the backward direction. Note: This is a check. Do not use for adjustment. (See
MLM 08-150, 08-151, 08-160.)
Bit Positioning - Improper bit positioning can be caused by an improperly adjusted
skew plate. Failures can appear as system abends and tape mark recognition problems.
Replacing the R/W head will appear to fix the problem for a very short time. Note:
Reference plate tool kit required. Refer to SA 9 and SA 10.

FRU Replacement/Swapping
The following FRUs are listed in the recommended replacement or swapping sequence.
If a part does not fix the drives symptom, return the swapped part to the original drive.
•
•
•
•

MST Logic Cards
Read Head Card
Write Head Card - Check to ensure that the write head card jumpering is correct.
Read/Write Head - When a new head is installed for diagnostic purposes, only the
AMP sensors need to be adjusted. If the head resolves the problem make certain
the Read/Write Adjustment procedures in the MLM (see 08-250) are followed.

READ/WRITE HEAD SERVICE HINTS
Factors that may indicate a failing head:
1.
2.

3. .
4.
5.
6.
7.

Media
System aborts indicating read or write failures
Tape runs off end of reel searching for a tape mark
No block detected on a write or write tape mark
High temporary write errors
High forward to backward analog signal ratio
Many OLT failures on test T3420F and very few errors on other tests
Varying analog signals
Making two amp sensor adjustments of .5 volts or greater in a short period of time

Factors that may indicate a failing head when the head is not failing:
1.
2.

3.
4.
5.
6.
7.

Low vacuum
Tape hitting obstructions in the tape path
Erase head
Filler block
Rewind plunger (3,5, 7)
Auto cleaner
Defective read or write head cards
Voltages out of adjustment
Poor tracking causing tape to buckle
Marginal media
Visual wear and poor forward to backward ratio
Replace only if failures are occurring

Factors that optimize head life:
1.
2.
3.
4.
5.

Good tape library maintenance
Proper and timely drive cleaning
Documenting problems
Good capstan tracking
Replace the head last

3420 READ/WRITE NTF CHECKLIST
If you have an intermittent read or write problem and can find nothing wrong with the
machine, perform the tests/checks indicated below before writing a "No Trouble Found"
IR. When completing an NTF IR, try to give information as accurately as possible.
Use Major Unit Code 960 instead of 980 whenever possible and include as much detail
as necessary in the narrative. Your IRs are the performance feedback mechanism we
use on the 3420/3803!

Read/Write Problems
Models 3, 5, 7
Most probable causes:
1.
2.
3.
4.
5.

Read head card defective
Write head card defective
T-AIL2, T-A112, T-AtM2 (NRZI}'tlefective
R/W head defective
Erase head defective

Initial checks:
1.
2.
3.
4.
5.

Air pressure and vacuum (see 08-400)
-4 Vdc and +6 Vdc supply in tolerance (see 08-570)
R/W head and cleaner blade must be clean
Capstan tachometer timing (see 08-130)
Degauss tape transport if problem is recurring

Reference MLM 5A-000
Models 4, 6, 8
Most probable causes:
1.
2.
3.
4.
5.

Read head card defective
Write head card defective
T-AIL2, T-AIJ2, T-AIH2 cards defective
R/W head defective
Erase head defective

3420 READ/WRITE NTF CHECKLIST (continued)
Initial checks:
1.
2.

3.
4.
5.

Air pressure and vacuum (see 08400)
-4 Vdc and +6 Vdc power supplies in tolerance (see 08-570)
R/W head and cleaner blade must be clean (see Note 4 on SB-001)
Capstan tachometer timing (see 08-120)
Degauss tape transport if problem is recurring

Reference MLM SB-OOO

TAPE DEVELOPING PROCEDURE
Purpose:

Gives CE a way of visually examining information recorded on a section of
magnetic tape.

Materials Needed:

Procedure:

• Developing solution (P/N 453522)
• "Low-tack" transparent tape (See Note 1.)
• Piece of clear plastic (such as old microfiche card, loose-leaf
page cover , etc)
• Felt-tip pen
• Flat surface (small table, etc) which can be moved to area in front
of tape unit
• Lint-free cloth (P/N 2108930) dampened with water

• Mount failing tape, without cartridge, and read to error. This is done
from 3803 CE panel (offline) or using "FRIEND" (OLT T0200A) or
customer utility such as "ditto," etc (online).
• When failure occurs press reset on drive and open front door. While
holding "cartridge-present" button pressed, manually bottom tape in
right column. This shuts off pneumatics.
• Open vacuum door and put small mark on bottom (non-oxide) side of
tape on each side of R/W head with a felt-tip marker.
• Carefully remove enough tape to reach the flat surface table, etc.
•

Shake the developing solution, then immerse the affected area of the
magnetic tape into solution. Use the felt-tip pen mark to determine
suspect area. Rock tape back and forth two or three times being
careful not to drag on bottom of can.

• Remove tape from solution and allow liquid to evaporate while still
rocking tape gently back and forth.
• Lay tape, oxide up, on the flat surface and use a small piece of transparent tape at each end of developed area to hold in place.
• Tear off an appropriate length of transparent tape and carefully press
it onto the developed tape. Try to avoid air bubbles, etc.
• Gently lift the transparent tape back off (peel it at an angle to avoid
damage) and phice on the clear plastic.
• The plastic with developed image may now be viewed directly or
under the microfiche viewer. Since the microfiche viewer magnifies
X30 be sure to divide any measured 'distance by 30.
67

TAPE DEVELOPING PROCEDURE (continued)
• Clean the magnetic tape thoroughly using the cloth dampened with
water. Allow it to air dry before rewinding and returning tape to customer for his cleaning procedure .
. CAUTIO~:
Conclusions:

Any foreign material left on the tape will damage the drives themselves.
Some of the more common problems which will be detected by tape developing are:
a. Partially erased records before an ERG. Usually caused by a glazed
capstan.
b. Noise in gap (defective erase head, etc).
c. Short gaps (indication of tape motion problem)
d. Damaged tape (oxide voids, etc).
See the following examples.

Note 1: The use of any other than "low-tack" transparent tape is discouraged as it may
remove oxide or leave adhesive on tape.

DEVELOPED TAPE SAMPLES
Here are some tips which may be helpful in analyzing the failure on a developed tape:
• Distance Relationships:

1.18"----..

.15"

• Erase Gap (ERG) Distances:
Density

Single
ERG

Successive
ERGs

6250

3.75"

3.45"

1600

4.2"

3.6"

800

4.2"

3.6"

7-Track

4.5"

3.75"

Density

Nominal
(Inches)

Minimum
(Inches)

6250

1600

800

.75

.68

• Interblock Gap Size:

7-Track

Developed Tape Examples
Good Data at 1600 bpi

!--_ _

To
BOT

Data
Block

~.6"~
Good
Gap

DEVELOPED TAPE SAMPLES (continued)
Good Data at 6250 bpi

.3"
Good

Gap
To
.....~~-BOT

Tape cinch/tape crease (1600 bpi)
caused by loose wraps on tape reel.

~.6"~
Good

Gap

Area
A

ERG
Performed

To
"""--BOT

• Drive was writing when "cinched" tape (small Z-folds) area appeared (area A).
• Prior to performing an erase gap the software tried to back tape up to last interblock
gap but stopped in creased area instead (thought it was the gap).
• From there a normal ERG command was executed and tape unit logged one temporary write error and continued normally.
.• Since damaged area was not completely erased by erase gap a permanent read error
then occurred when tape was read.

3420 RD/WR DATA FLOW
Write Data Flow
0
1

~~~;

....

Tape
Unit
Interface
Connector

2
3
4

Connector
AIN4

AIK6

AIJ2

Connector
AIT3

5
6

Read and Write Data Flow
Within 3420
- Models 4,6,8 Only (See MLM 58·100 For Details)

R/W Head Pin Layout
(Models 4,6,8 Only)

Mounting Plate
4
6
0
1
2
p
3
7

0
0

0
0
0

0
0

t:o
a;
:r:
en

0
0
0
0

0
0

0
0
0

0
0

4
6
0
1
2
P
3
7

Read Section
Note:

Read Data Flow
0

Read
Card

3
4

Connector
AIN3

Connector
AIN2

AIL2

Tape
Unit
Interface
Connector

Wnte Section
The center tap
is the middle pin
on eacli track.

3420 RD/WR DATA FLOW (continued)
Write Data Flow

Tape

~~~~..... ~~~~face

Connector
AIN4

AIK4

Connector
AITJ

AIJ2

Connector

7T
-rae k

9 Track

Mounting Plate

AIK2
NRZI
Write
Deskew
(NRZI
Only)

Read Section

The center tap ~
is the middle pin - - on each track.

Write Section

fOJ ~D'
:

~ ~

0
0

0
9

6
7

2
3
4
5
6

0
0

~ ~

0
0
0

Read Section

(J)

WnteSectlon

Read Pata Flow

~~~ectQr 1----4----------.;

Read and Write
Data Flow Within 3420
- Models 3, 5, 7 Only (See MLM 5A·100 or
PF 5·100 for Details.)

AIM2
NRZI
Read
Deskew
(NRZI
Only)

AIL2

Connector
AIN2

Tape
Unit
Interface
Connector

To
3803

3420 TAPE MOTION SERVICE TECHNIQUES
Consider performing the following tests if you are experiencing intermittent 3420
failures relating to tape motion. The symptoms should first be analyzed using MLM/
Pathfinder. \
Some of the more common symptoms associated with these service techniques are:
Symptom
Tape Slip
Partially Erased Records
Permanent R/W Errors
High No. of Temp R/W Errors
Dropping Ready
No Tape Motion
Dumping Tape

Possible Cause

Glazed Capstan
Glazed Capstan
Also see 3420 R/W
Glazed Capstan
Service Techniques
Glazed Capstan
Leaky Transfer Valve or Column Vacuum
Door
Open Capstan Motor Segment
Open Capstan Motor Segment

Glazed Capstan Cleaning
This procedure is performed only if glaze cannot be removed by normal cleaning.
CAUTION:

This procedure, if not done properly and with extreme care, can
shorten the life of (or damage) the capstan. If the capstan edges are
rounded or flat spots are created, tracking adjustments will not be
possible.

Verify that this procedure is necessary:
1.

Perform Capstan Cleaning-Normal Procedure (see 85-004 if necessary).

Perform T3420W OLT diagnostic test.
•

Run OLT T3420W to determine the size of interblock gaps.
[0.301 inches is nominal for models 4/6/8 and 0.600 inches
in nominal for models 3/5/7.]

3420 TAPE MOTION SERVICE TECHNIQUES (continued)
3.

Check diagnostic printouts for signs of variance.
•

Gap sizes exceed limits specified in OLT.

If the tape is varying, the glazed capstan cleaning procedure may be necessary.
Proceed as follows: (Refer to "Tape Slipping" under 3420 Read/Write
Service Techniques.)
a.

c.
d.
e.
f.
g.

Assemble an abrasive tool using 600 grit paper IBM PIN 460107 attached to
a six-inch steel rule with a double back adhesive tape such as 3M Y-9122* or
4282*. You may also use rubber cement or printer carriage tape glue.
Remove the left threading channel. Place the steel rule with 600 grit paper
squarely on the capstan and then just break the glaze on the capstan with the
abrasive tool while rotating the capstan by hand.
The intent is not to remove the glaze with the tool but to break through the
coating to allow the tape cleaning solution to soak under it.
Moisten cotton swabs with tape cleaner and scrub the capstan rubber
thoroughly, until the capstan attains a dull rubber finish.
Follow up with a lint-free cloth moistened with tape cleaner to remove all
traces of the cotton swab.
Verify the effectiveness of your cleaning by repeating the T3420W OLT
test.
Repeat the cleaning operation only if step e shows IBG variance.
Capstan dynamic alignment (trackip.g) must now be checked.

Capstan Motor Test
Unplug the capstan motor from the capstan board and measure across the two wires
going to the motor with an ohmmeter. Rotate the capstan slowly by hand while watching ohmmeter. The meter will deflect some but should never go to an open condition
(open armature segment). If an open condition occurs the capstan motor should be replaced.
Note:

In the pneumatics portion of the drive verify normal pressure and vacuum adjustments and checks per MLM 08-400 before 'performing the following tests.

Column Vacuum Leakage Test
If you suspect a column vacuum leak the following procedure is a good way to check
column vacuum level:
- Take drive offline and install tape motion tester.
*Trademark of the 3M Company
74

3420 TAPE MOTION SERVICE TECHNIQUES (continued)
- With drive unloaded, disconnect tubing to L3 or R3 vacuum switch.
- Use a "Tee" (P/N 1767025) to insert vacuum gauge (P/N 5495384) in the line.
- Reconnect tubing to L3 or R3 then load tape and read gauge. Vacuum level should
be:
Model

Vacuum

3,4,5,6

21±3"

27±3"

31±2"

- Move tape forward and verify that vacuum level remains within tolerance.
- Move tape backward and verify vacuum level.
- If vacuum levels read low on these tests, clean column-to-glass mating surfaces and
check column glass adjustment.

Cracked Pressure Hoses
When analyzing any problem relating to pneumatics check for cracked pressure hoses.
The hose between pump and filter should be closely examined. If a hose is found to be
cracked replace it. Do not cut the hose back because it will soon crack again.

Transfer Valve Leakage Test
1.

Cover the stubby column ports with masking tape. See Figure 1. Do not let the
tape overlap the stubby bars.

Place an 8-inch piece of magnetic tape in the bottom of the right vacuum column to
prevent vacuum from entering the column.

Cut a 12-inch piece of magnetic tape and lay it over the left reel tach just below the
read/write head. Ensure that the tape loop is approximately in line with the bottom
of the capstan. See Figure 1. Bypass the door interlock.

With no tape on the right reel, press LOAD REWIND. If the tape strip is pulled intothe left column before load check occurs, there is sufficient leakage to cause intermittent problems and the transfer valve must be replaced. Repeat the test several
times to ensure that the valve is bad.

Remove the masking tape from the stubby column ports and clean 'the area
thoroughly with a cloth dampened with tape cleaner. Remove the magnetic tape
from the right and left vacuum columns.

3420 TAPE MOTION SERVICE TECHNIQUES (continued)
6.

If 3420 Drops Ready:
, Analyze Sense or Scope Error Latches to Find Reason

Error
Description

Drive
Error
Latches
Error
(See Note) Sense

Probable
FRUs

Further
Analysis

Byte 7
Bit 0

•
•

Optic Lamp
AlD2

See Logic
FTl14

Byte 7
Bit 1

•
•
•
•

L4 Vac Switch
L3 Vac Switch
Left Reel Board
Capstan Tach

•
•

R4 Vac Switch
Right Reel
Board
Capstan Tach

Fiber Optic
Lamp Failure

+ At S07

Tape Bottom or
Pull Out of Left
Column*

+ At U02

Tape Bottom or
Pull Out of Right
Column*

+ At U05

Byte 7
Bit 2

Reset Button
or
Door Interlock

+ At S03

Byte 7
Bit 3

(Note
Latched)

•
•
•
•
•
•
Air Bearing
Pressure or Right
Reel Hub Failure

+ At S04

OV /UV (Power
Check) or No
Cooling Air to
Capstan Board

- At S02

Byte 7
Bit 6

•
•

Byte 18 •
Bit 0
•
•
•

Power-On Reset

+ At M05
(Not
Latched)

Safety Bail Reset

Models 3,5,7

+ At E2B09
(Not Latched)
Models 4,6,8
+ At D4B09
(Not Latched)

•
•
•

Reset Button
Door Inlk
Switch
TA1C2
AB3F2
AA2D2
Leaking File
Hub
Air Bearing or
Hub Switch

Drive error latches are
on following card:

Could Be Caused By
Operator.

See Logic t - - - - - - - - - - - 1
FTl14
If A Solid Failure Tape
Will Not Dump Into
Cols on Load.

Go To
lA-OOO
or
1 B-OOO

These Errors Cause Reel
Board EPO Relays to
Drop (Loss of Motor
Control)' Tape Bottom
Will Then Drop Ready

A1C2
A1H2
Fuse Detect
Card

See Logic
FTl12

These Are Not Normal
Drop Ready Conditions.
However, Intermittent
Failure May Show as a
Drop Ready.

Models 3,5,7
• A1C2
• Al E2
Models 4,6,8
• A1K2
• A1D4

*Vacuum switches
are high-failure items.

Mod 3, 5, 7 - H2
Mod 4, 6, 8 - M2
•

Could Be Caused By
OV /UV Detection or
Capstan Board Cooling
Sensor. See Byte 18
Bit 0 Below.

Check Voltages
Dirty Filter
Defective
Cooling Fan
Check Cooling
Air Sensor

NOTE
•

Go To
3A-ll0
or
3B-ll0

Notes

Voltage Levels are:

+ is - .85
- is -1.85

See Logic
FT283

3420 TAPE MOTION NTF CHECKLIST
Perform these checks precisely as described in MLM.
Check, adjust if necessary:
• BOT/EOT (08-580)
• Capstan Tachometer Adjustment (08-120 or 08-130)
• Pneumatics (08-400 [all] and 08420)
Reference MLM START 1.

3420 TAPE MOTION
Pneumatic System
with Thread Status Active
File Protect
Indicate Switch
Pressure Sensing Switch
Scope Points
'Ground = Pressure Good
-4vdc = Pressure Bad
Air Bearing
Pressu re
E2M03

Model

Automatic Latch
Upper Restraint
(Cartridge Pressure)

Reel Latch
Pressu re
E2J02

Lower Restraint
(Threading Chute)

D4J02

l~i~jiili~iiiiIil Pressure
1::'::':::,:1 Vacuum

Left Threadi ng
Channel (Upper)
Right Threading
Channel (Upper)

Cleaner Blade
Capstan Motor

Model 8 Only
Right Threading
~~~ Channel (Lower)
Transfer Valve Assembly
(Actuated for Threading)

Vac Switch
Layout is Typical
But May Not Be the
Same on Your Machine

Left Reel Hub
Vacuum Columns

mp
pr"l
From Cooling Distribution Box

tor
Adjustment
Model
8 Only

Column Vacuum Switch
Scope Points
Ground = Tape Above Switch
-4vdc = Tape Below Switch
L1

B2S02

B2508

B2S03

B2U09

B2U04

B2S09

C2P09

C2M09

} Refer to MLM 08-450

3420 TAPE MOTION (continued)
Pneumatic System
with Thread Status Inactive
File Protect
Indicate Switch
Pressure Sensing Switch
Scope Points
Ground = Pressure Good
-4vdc = Pressu re Bad
Air Bearing
Pressu re

Model

E2M03

3,5,7

Automatic Latch

Reel Latch
Pressu re

Upper Restraint
(Cartridge Pressure)

E2J02

Lower Restraint
(Threading Chute)

D4J02

Left Threadi ng
Channel (Upper)

IIIl!l!l!l!l!l!Il!l!1 Pressure

1::··1 Vacuum

Right Threading
Channel (Upper)

Cleaner Blade
Capstan Motor

Model 8 Only
Right Threading
'-----II~~ Channel (Lower)

Vac Switch
Layout is Typical
But May Not Be the
Same on Your Machine
Column Vacuum Switch
Scope Points

-----------------

pr"lm

From Cooling Distribution Box

tor
Adjustment
Model
8 Only

Ground = Tape Above Switch
-4vdc = Tape Below Switch

B2S02

B2S08

B2S03

B2U09

B2U04

B2S09

C2P09

C2M09

} Refer to MLM 08450

3420 POWER SERVICE TECHNIQUES
• When checking DC voltages use all standard safety precautions.
The +6 Vdc should be adjusted with the 3420 in write status, ready, away from
load point, and moving tape.

3420 Power Check, No File Protect or Power Related Problems
After using the MLM without results on power type problems, the following list will
give some of the known problems in this area. With power type problems it is a good
idea to go over the supplies checking for loose screws, fuse holders, cable connectors,
etc. Check supply levels. Vibration may help aggravate failures.

1.
2.
3.
4.
5.

6.
7.
8.
9.

10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.

Bad connector to power resistor panel. Shows on LOAD.
Loose screws on transistors on power interface board. -4V low.
R 67 on fuse detect card defective. J6 cable shorted to frame.
Bad solder connections to fuses.
Power check air flow bit on, command status reject. Loose capacitor screws.
Slip on connector to power interface board solder connection bad or rivets
loose or dirty filter.
Power check light glows dim. -4V return screws loose.
Power check light flashes. Phasing bad or TPl-1-2-3100se.
Drops vacuum. Bad solder connection O/V U/V reference card socket.
Power check, load check lights flicker. K1 relay on reel board points burn, 48V
supply drops. Loose 48V wire from C8 to HS1 on mounting block for CR 11 12
or loose TBl-6-7.
Bad connection on J7 socket.
Power check when drive selected. Loose wire on power interface board where
wire comes through board to transistors.
Rewind unload in middle of job. Short from MSC card to cover.
Heat sink 1 on 48V supply has loose wire.
Bad power interface board. No -4V.
Fails to write, dumps tape. Bad 6V supply, or bad connection to fuses on piggy
back supply.
Fails on write operation. Bad power interface board.
Equipment check unload in middle of job. Loose fuses on piggy back supply,
has ripple on supplies.
Blows fuse 6 and CP 1. Bad SCR card, SCR1, SCRll.
Select light after load. Flat cable from 11 on reel board pinched and shorting between frame and power interface board.
Equipment check, power check light on dim. Bad monitor card.
Bad fuse detect and EPO card.
Blows fuse 3 on piggy back supply. Bad write driver card.
Damages tape on rewind. Bad reel motor board.

3420 POWER SERVICE TECHNIQUES (continued)
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.

45.

Bad CB 1, or loose screws on CB.
Defective diode board in 4V supply.
Frame ground at -12 volts. Erase head shorted to frame.
Blows fuse 10 or 12. Loose screws on TB 5-1.
6V high or has ripple, bad power interface board.
6V varies or blows reg card, bad connection 17-7 to 17-8.
Reed relay on OV/W card.
Blows fuse 6, MSC card shorted to support bar.
Diode assembly on YB020.
F13 - PCB board.
F12 - Write PCB board.
F14 - Shorted write head card.
Blows write driver card and F14. Read write cable plugged one pin off.
No output +12, -12, 4V or 6V. Shorted cap Cll on XFMR.
Blows OVjUV card. HS-l transistor on power interface board.
Load check light flashes - loose fuse 3 or F3 holder.
Lights flicker with vibration - suspect any fuse holder.
Plus 6 volts ripple or varies ... CRI9, 20, 21, 22 on PC2.
Command reject ... ribbon cable from 01 A Al board smashed between frame and
pneumatics cover.
ID burst checks ... loose capacitor screw in power tub.
Power check, no -4V or +6V output. Transfer valve picked solid. (9XXXX series
drive) power interface board PIN 2515544, bad solder connection at connector
number 10.
Intermittent channel errors (ALV hangs, ALV errors) or R/W error count high.
Scope 4 and 6 volt supplies for excessive ripple during failure if possible. Failures
are almost solid while there is ripple and then disappears when the ripple goes away.

3420 POWER NTF CHECKLIST
• Check that air filter is clean and blower is running smoothly.
• Check/adjust DC voltages (watch for excessive ripple content).
• Check for loose power supply screws if problem is recurring.

3420 POWER - DC VOLTAGES
CAUTION:

Be sure to use a digital voltmeter, PINs 453046, 453585, or equivalent,
when making adjustments and use all safety precautions.

Notes:
1.

Ensure that the tape unit is loaded, ready, and in write status before checking or
adjusting +6 V power supply. After check or adjustment, measure the voltage at
T-Al G2Bl1. If voltage exceeds +6.24 V, check the file protect circuitry for resistance.

The maximum allowable ripple voltage is 24 mv peak-to-peak measured at the
power. supply.

Models 3, 5, and 7
If you have an unmodified power supply, check voltages at the following test points.

Power Supply Value

Test Point

Ground

+6v (±O.05v)(See Note 1 and 2)

T-A1G1 E09

T-A1G2D08

-4.05v (±O.05v)(See Note 2)

T-A1 N3D02

T-A1N3D08

-48v (+7v, -9v)

TB1-9

TB1-8

+12v (±1v)

TB2-1

TB1-8

-12v (±1v)

TB2-5

TB1-8

+11v (+2v, -1.2v)

TB3-12

TB2-4

Basic Power Supply

3420 POWER - DC VOLTAGES (continued)
If you have a modified power supply, check voltages at the following test points.

Power Supply Value

Test Point

Ground

+6v (±O.05v)(See Note 1 and 2)

T-A1G1E09

T-A1G2D08

+11v (+2v, -1.2v)

TB2-1

TB2-4

-4.05v (±O.05v)(See Note 2)

T-A1N3D02

T-A1N3D08

-48v (+7v, -9v)

TB1-9

TB1-8

+12v (+1v)

TB3-1

TB1-8

-12v (±1v)

TB3-5

TB1-8

+30v (±O.5v) *

TB2-3

TB1-8

-12v (±1v)*

TB2-2

TB1-8

+12v (±1 v) *

at Fuse 7

TB1-8

* Used only for OV /UV sense.

Modified Power Supply

3420 POWER - DC VOLTAGES (continued)
Models 4, 6, and 8

If you have an unmodified power supply, check voltages at the following
points.
Power Supply Value

Test Point

Ground

+6v (±O.1v)(See Note 2)

T-A1G2B11

T-A1G2D08

-4.05v (±O.05v)(See Note 2)

T-A1 H1C09

T-A1G2D08

-48v (+9v, -9.6v)

TB1-9

TB1-8

+12v (+1.4v, -O.9v)

TB2-1

TB2-4

-12v (±1.4v)

TB2-5

TB2-7

+11v (+1.7v, -1.1v)

TB3-12

TB2-4

If you have a modified power supply, check voltages at the following
points.
Power Supply Value

Test Point

Ground

+6v (±O.1 v)(See Note 1 )

-T-A1G2B11

T-A1G2D08

+11v (+1.7v, -1.1v)

TB2-1

TB2-4

-4.05v (±O.05v)(See Note 2)

T-A1H1C09

T-A1G2D08

-48v (+9v, -9.6v)

TB1-9

TB1-8

+12v (+1.4v, -O.9v)

TB3-1

TB3-4

- 12v '( ± 1. 1v)

TB3-5

TB3-7

3420/6250 CONVERSION TIPS
The following are some hints for field conversion.
IMPORTANT:
• Follow the instructions in the conversion books very carefully .
• The majority of problems that occur after conversion result from cards or cables not
seated correctly and dirty, bent, or recessed pins.

Conversion Kits
Recommended actions prior to installing conversion kit.
A.

General
1.

The EC check list (3420 ECA 056)
It is of the utmost importance that the EC checklist be correct. If it isn't, you
will get the wrong parts. Do a physical check of each E/C that is supposed to
have been installed.

The prerequisite EjCs must be installed on the machine and the machine tested prior to installing the conversion kit.

RPQ, features

If features and/or RPQs were ordered for the 3803-1,3420-3, 5, 7 they
must be installed and operational before doing the conversion.

If features and/or RPQs were ordered for the 3803-2 configuration, they
must be installed after the conversion is complete and operational.
40

Recommend the use of a Circuit Test Probe Part 453587 to expedite verification that the adds and deletes are correct.

Ensure that you are familiar with the conversion instructions before starting.
It is recommended that you read them at least once prior to starting the conversions.

Review ITIPs (and data bank) to become aware of problems that may be encountered during conversion.

Prior to installing logic cards and connectors make sure there are no broken
or bent pins. Inspect for recessed or loose pins on the data cable connectors
(channel-to-tape control unit and tape control unit-to-tape unit).

3420/6250 CONVERSION TIPS (continued)
8.

All connectors and logic cards installed/replaced as called out in the conversion should be "popped" (eg, seated, removed and re-seated) a few times to
assure a good contact.

The installation of the tape cleaner does not eliminate the present head cleaning procedure.
-

Only the logic board and logic cards in the conversion kit have been tested on a
"slave machine"; cables and jumpers have not.

Double check all card plugging to ensure that they reflect the converted status of
the machine. The exception is on page 0950 of the TU Conversion book. The
original model number of the TU should be plugged, not the new model that it was
converted to.

3420 Conversion Hints
After removing "old" fiber optics lamp, clean the ends of light pipes in the horseshoe with a damp, lint-free cloth. After power has been turned on, allow the "new"
fiber optics lamp to warm up for 20-30 minutes.

Assure that the R/W card cables are connected correctly. It is possible to
miss the top pins of the R/W card connector.

Before removing the R/W cable guide, observe how it is mounted on cable
connector and reassemble it the same way when you have finished modifying
the cable.

Remove the coating on the R/W cable connector before soldering wires to it.

When the tape unit interface adapter shoes are installed correctly you should
see the silver plating.

Page 0490 of the Tape Unit Conversion book is causing some confusion. The
wires are connected to AEI and AE2 connectors which are located on the
small board (PN 4169370) on the side opposite to where the components are
mounted.

Assure that the vacuum column restrictors are installed properly.

If after the conversion you experience R/W problems check the auto cleaner
adjustment (page 1080). Also, assure that the auto cleaner is not activated.
This can be checked visually by removing the cover of the R/W cards (on the
front of the machine). With the columns loaded and looking down towards
the head you should see part of the white ribbon used in the auto cleaner.

3420/6250 CONVERSION TIPS (continued)
8.

OLT 3420L should be run using the same magnetic tape that you used when
you adjusted the amplitude.

Usted below are the major conversion efforts that apply to all models:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.

Replace tachometer assembly and capstan control power board.
Replace R/W head.
Replace R/W cards.
Add new read cable.
Rework write cable.
Replace logic board.
Add six new MST cards.
Add new power cable.
Remove high-speed rewind plunger.
Remove inspection mirror and lamp.
Add tape cleaner assembly.
Rework write-enable circuit.
Rework three logic cables.
Rework pneumatic distribution.
Rework or replace power supply.
Rework or replace power interface (miscellaneous) board.

If converted to a Model 6 or 8:
1.

Replace vacuum column glass with one that has a resonator.

The following additional rework is required for conversions to Model 8:

1.
2.
3.
4.
5.
6.'

Replace the
Replace the
Rework the
Rework the
Replace the
Rework the

capstan motor.
vacuum pump.
pneumatic supply if the drive motor is not in the middle.
transfer valve.
reel motors and boards if converting from Model 3 or 5.
power door if lower glass was not installed.

Conversion Tips from Data Bank
3420

Reference page 0453 of Conversion Instructions. Do not remove the "0" ring
type washer, placed between reference "B" and "F". What should be removed
is about 1" - 1
long and shaped like an "L".

3420

Erratic high-speed rewind - check resistor and cover assembly part PIN. For
Model 6 PIN 1845820.

3420/6250 CONVERSION TIPS (continued)
3420

Conversion reel motor change - when replacing reel motors of different styles, a
cooling hose reducer PIN 2513076 may be required, as well as different antirotation screws PIN 0438579 or PIN 0438581.

3420

Tape crease after model change - capstan to stubby bar clearance ora pneumatic
pressure check for possible air leaks may need to be done.

3420

Offline tester conversion (6250), check MLM page 90-170.

3420

Fail to load, reels do not turn - booster supply board PIN 2515544 defective.

3420

Velocity check after conversion from a Model 3 to Model 7 - resistors for
assembly PIN 2523731 should be 1 Ohm, 1 Ohm, 2 Ohm. They were 2 Ohm,
2 Ohm, and 10 Ohm, even though the correct part number was stamped on the
assembly.

3420

No read or write after conversion (to 6250). Open paddle land to AIN7D02 or
could be an open solenoid or cable.

3420

Various errors after model change - check ALD page A6106 for proper positioned jumpers (2 pages).

3420

Won't load (any model) reels won't turn, transfer valve or KI won't pick, but
the pneumatic motor runs. Incorrectly connected cable (El and E2 connection)
to the piggy-back supply board attached to the booster supply.

Compatibility problems between drives can be caused by tracking out of adjustment, or
if this adjustment is OK, the tracks are not centered on tape. Develop tape and place it
on the viewer to observe. The proper positioning of the head to tape relationship is done
by the Skew Plate. A special Skew Plate adjusting tool is necessary to do this (included
in the Reference Plate replacement kit,BM 4298806). Reference SA 9 and SA 10.

3420 PM SCHEDULE
Code
1--......-

U R
0

Location
Operation

Action

Frequency

Door Slide
and Stop
Pin

4 months

Lubricate the door slide and the stop pin with
IBM #17.,

General
Cleaning

4 months

1. Clean front deck and base.
2. Remove tape cleaner block and clean with
tape cleaner.
3. Remove air bearing (D-bearing) next to
EaT/BOT block and clean. Inspect guide
behind bearing and replace if grooved.
4. Clean NRZI guides.
5. Clean EaT/BOT channel mirror.
6. Clean the fiber optic lamp. Use a tissue
lightly moistened with water.
CAUTION:

Allow lamp to cool before
cleaning.

Remove the manifuld and fiber bundles to
provide access to the lamp. Replace the lamp
(08-620) if it is not clear. Note: Cleaning or
replacement of the fiber optic lamp requires
the readjustment of the EaT/BOT and capstan
squaring.
Capstan
Tach
Squaring
Circuit

4 months

Check and adjust Capstan Squaring. See 08-120
or 08-130. Ensure capstan is free from dents
and does not bind.

Capstan
Tracking

4 months

Check and adjust Capstan Tracking. See
08-000.

EaT/BOT

4 months

Check and adjust EaT/BOT. See 08-580.

3420 PM SCHEDULE (continued)
Code
r--r-U R

Location
Operation

Frequency

Action

File Protect
Pin

4 months

1. Push plunger in, check for binds.
2. Check that plunger extends in front of the
right hub flange.
3. Replace unit if any checks product unsatisfactory results.

Power
Window
Safety Bail

4 months

Check for the correct operation of the power
window safety bail. If incorrect, tighten the
setscrew in the safety bail terminator, and
adjust the safety bail switch assembly (see
08-000).

Parts
Replacement

12 months

Order one of the following B/Ms for required
parts.
- B/M 8492273 Puralator type filter
- B/M 8492274 Cuno type filter

Tape
Cleaner
Block

12 months

Replace the tape cleaner block. Supplied with
parts replacement B/M.

Pneumatic
Supply Belts

12 months

Check pneumatic supply belts.

Input
Filter

12 months

Replace filter element of the pressure pump
input filter. Supplied with parts replacement
B/M.· Check for Puralator or Cuno type.

Cooling
Filter

12 months

Clean cooling air filter or replace as necessary.

Air
Bearing
Cleaning

12 months

1. Remove bearings.
2. Brush each bearing to remove oxide deposits.
3. Install new decorative covers on air bearing.
Supplied with parts replacement B/M.
4. Check pressure (see label).

12 months

Check the dc voltages. (08-570)

Voltage

3420 PM SCHEDULE ( continued)
Code
-DR

Location
Operation

Frequency

EaT/BOT

12 months

Remove EaT/BOT by removing the two
screws and gently move block forward being
careful not to damage the fiber bundles.
Clean EaT/BOT with a cotton swab
dampened with tape cleaner. Replace EaT/BOT
block.

Capstan
Motor
Mod-8

12 months

Clean screens on back of motor with vacuum
cleaner.

Radius
Sense

12 months

Clean the ends of the fiber optic bundle with
a damp cloth, see 08-610 for removal. Apply
a felt pad to the handle and lightly dampen with
tape cleaning fluid. Hold pad to the inside front
of left reel flange and spin by hand. This will
clean the reflective strips located inside the left
reel.

Reel Tach

12 months

Check reel tachs for glaze. Replace reel tachs
if glazed.

Glass Bead
Tape

12 months

Inspect glass bead tape on stubby bar and in
vacuum columns. See note. Ensure that
stubby bars are not loose and have proper
clearance. See 08-000.

High Speed
Rewind
Plunger

12 months

Check operation of the High Speed Rewind
Plunger. (08-000) Models 3,5, and 7 only.

Autocleaner
Check

12 months

1. Check operation of autocleaner by marking
the ribbon and observing ribbon movement.
The ribbon should move from bottom to top.
2. Check the supply of autocleaner ribbon.
Order a new autocleaner cartridge when
approximately 3/4 inches of ribbon is visible
through the cartridge window. Models 4, 6,
and 8 only.

Preamps

12 months

Check and adjust preamps (08-290 or 08-300).

Action

3420 PM SCHEDULE (continued)
Code
·U R
3

Location
Operation

Frequency

Action

Pressure
Tubing

36 months

Replace pneumatic pressure tubing
(order B/M 4416408).

Output
Filter

36 months

Replace with PIN 2524998.

Vacuum
Tubing

48 months

Replace vacuum tubing
(order B/M 4416409).

Note:
Inspect the glass bead surface of the stubby bars and' vacuum columns.
Replace if the glass bead is nicked, scratched, burred or has an area obviously
worn to the touch. (If not obviously worn, do not replace.)
Run finger on the glass bead surface at the bottom of the vacuum column.
This is a good glass bead surface and may be used as a reference.
A worn glass bead surface will cause tape motion problems.

3420 SALES FEATURE CODES

Feat
Code
3350
6407
.9
+-'
6631
U
~
;:l
6420
~
6425
9903
~
~
9905
9041
9042
9043
rJ'l
9045
1-4
.Q 9046
0
u 9051
9053
9054
If None
~
~

Model
3 4
Description
5 6
7 8
Dual Density (1600 + 800)
X
Choose
Seven-Track
One and
X
Only One X
Single Density (1600 Only)
6250 Density
Choose
X
Only One.
6250/1600 Density
X
208 Vac Power
Choose
X X
230 Vac Power
Only One X X
Red Covers
X X
Yellow Covers
X X
Blue Covers
X X
Gray Covers
X X
White Covers
X X
Red Machine Reel
X X
Blue Machine Reel
X X
White Machine Reel
X X
Gray Machine Reel (If None Specified)
X X

3420 (ALL MODELS) STATUS IDENTIFIER
Status

Identification

NRZI Tape Path - New or
Converted DD TUs

Check for spring loaded guides attached to the
D-bearing and ramp.

Piggy-back Power System
34090 through 37099
43001 through 43084
45000 through 45054
90000 through 99999

Check for a large visible capacitor just below fuses
10-13 on the outside rear of the power supply.
(Piggy-back supply)

"Model 3 Only" Capstan
Motor

Check rear casting on capstan motor for "Mod 3
Only" markings.

The following 3420 ECA list is current as of the publishing date of this manual. Consult
microfiche listing for most up-to-date information.
E = Essential Change
A = As Required Change

101

3420 ECA CHECKLIST
Machines
Affected

ECA

E/A

Description

Checkpoint

001

733966

C-Test Exit

Check for an on/off
line CE switch

All

002

733999

C-Test Exit
(14 REAs)

Check for PIN 8218287
in socket location 01 AAIH2

Mods 3,
S, 7

003

734021

Logic change to
su pport cost reduced B2 card
- paper only -

Check for card PIN
8218286 in 01AAIB2

All

004

734030

Install positive stop
control. Prevents
short gaps and missing records when
running an oscillating
sort program. Improves LS rewind
performance on
Mod 3s. Picks up
E003 (picked up
by E007)

Check for PIN 8216714
at 01 A-AI F2 and PIN
8218290 at 0IA-AIG2.
Check for EC 734030B.

All

005

734045

Prevent erasing tape
with a +6 volt splash
when loading tape.
Route +6 Vdc to
write driver card
through R/W cable
ferrite. (REA 2422457)

Mods 3,
Check for discrete wire
routed through the R/W 5, 7
cable ferrite. Some mach
may not have it routed
this way. It is the wire
from TBI-I0 on logic
ga te and should go
through ferrite.

006

733698

Power supply logic
(paper only)

Check logic pages FT265 All
and FT452.

007

734030B

Correct mid-tape load Check logic pages FT265 Mods 3,
5, 7
failures. (REA 24and FT452.
23860) paper only (composites E004)

008

734062

Prevent tape damage.
Prevent catch from
popping out of lower
restraint when using
a cartridge. (REA
24-23847)

103

Check the catch to ensure All
good retention.

3420 ECA CHECKLIST (continued)
Checkpoint

Machines
Affected

ECA

E/A

Description

009

734063

Check for 16 holes in
High-speed rewind
high-speed rewind
plunger. (REAs 24plunger
23855,56 and 2423844) (Replaced by
E024)

All

010

733704

Check for disc-type
WTC only replace
paper capacitors C14 caps C14 and CIS in
the SO Hz power supply
and CIS (to correct
an REA problem) (SO
Hz only) (REA 2423866)

All

011

734061

Ensure proper operation of rewind
solenoid to prevent
high-speed rewind
plunger from sticking in the down
position.

Check for a 3 psi label
then ensure that the
spring is removed
from the square
high-speed rewind
solenoid. Marked 3 psi.
If 5 psi or round, ECA
not required.

All

012

734035

Correct loading probIem. ,Added orifice in
vacuum column to
prevent tape dump
during loading.
(REAs 24-22487,
471,473, and 2422483). (Replaced
by EC 734951)

Check for orifice in left All
vacuum column manifold
by removing the vacuum
hose. EC 734035 installs 0.7 SO" orifice/EC
734951 installs 0.625"
orifice.

013

734046

Prevent tape damage
and tape dump.
(REA 24-23866)
(picked up by E026)

Check for PIN 8218292
at 01A-A1C2

All

014

734056

Prevent velocity
checks air bearing
collapse due to low
air bearing pressure

Check air bearing pressure decal for 83 inches
of water on M7 NRZI
machines or 69 inches
of water on other
machines.

Mods 3,
5

104

3420 ECA CHECKLIST (continued)
Machines.
Mfected

ECA

E/A

Description

Checkpoint

015

734374

Before loading with
mini-reels. Vented
right threading channel

Check for large (0.38")
diameter hole in right
threading channel.

016

734368

Prevent belt turnover
by relocating pneumatic supply motor.

Ensure proper belt align- Mods 3,
5, 7
ment by checking that
the front mounted pneumatic supply motor is in
the center position.

017

734231

R-C network installed Check for large R-C net
in power supply across in ac box.
channel air solenoid
relay contacts to prevent load checks.
(REA 24-23903)

018

734382

Add redundant
vacuum switches.
(REAs 24-23902 and
24-23933). (Note:
Mandatory on B03,
5,7).

Check for parallel vacuum switches. Part of
them may be mounted
on rear of mounting
bracket.

Mods 3,
5, 7
B03
B05
B07

019

734372

Improved pneumatic
latch (picked up by
E033)

Check for leaking reel
latch. (Note: Obsoleted by E033 EC 734466
(new latch)

Mods 3,
5, 7
B03
B05
B07

020

734394

Corrected logic page
ZT023. - paper only -

Check logic page ZT023
for EC 734394.

Mods 3,
5, 7
below

All

SIN:
31659
52401
72075
021

734068

Correct PE write current for the P-burst
and tape mark.

Check for PIN 8218291
at 01 A-AIJ2.

Mods 3,
5, 7
B03
B05
B07

W/O
7-Trk
105

3420 ECA CHECKLIST (continued)

ECA

E/A

Description

Checkpoint

Machines
Mfected

022

734280

Power supply logic
update. - paper only -

Check for EC 734280
on YB036

Mods 3,
5, 7

023

734244

Changed heat sink in
power supply man
status card. (REA
24-23909)

Check EC 734244 label
on manual status card
in power supply.

All

024

734392

High-speed rewind
plunger (REA 2423964) (replaces
E009)

Check for an IBM-1
stamp on the 16-hole
high-speed rewind
plunger.

Mods 3,
5, 7
B03
B05
B07

025

734395

Improve threading of
crinkled tape leaders.
Replaces manifold
and orifice.

Check for a one piece
threading vacuum hose
on 3420-3, 5. Check for
an orifice in this hose on
3420-7.

Mods 3,
5, 7
B03
B05
B07

026

734391

Activate high-speed
Check for logic card
field control. Mand- PIN 8218294 at 01Aatory on machines
A1C2.
with EC 734046.
Corrects ESD problem
caused by E013.

Mods 3,
5,7

027

905864

World Trade Only

---------

028

734369

Install modified write
driver card to prevent
write and erase current splash on tape
during a mid-tape
load. (REAs 2423889, 24-23874).

Check for EC 734369
on EC 734470 stamped
on the 9-track write
driver or EC 734038
stamped on the 7-track
write driver.

Mods 3,
5, 7

029

734456

Add integrator to
window closed
switch. This EC corrects a safety problem (REA 24-25031)

Check for 1000MF
capacitor on p.ower
window board.

Mods 3,
5, 7
B03
B05
B07

106

3420 ECA CHECKLIST (continued)
Machines
Affected

ECA

E/A

Description

Checkpoint

030

734467

Improve write reliability by adding a
write enable relay to
file protect circuit
to carry the +6V
write current to the
write card.

Check for relay assembly Mods 3,
5, 7
close to the file protect
pressure switch.
B03
B05
B07

031

734468

Install a vented
vacuum column to
help eliminate mylar*
contamination.
(picked up by E041)

Check for ~" gap on
column bars between
reference plate and
vacuum column.

Mods 3,
5, 7

032

734743

Obsolete - Replaced
by ECA 051.

---------

---

033

734466

New reel latch. picks
up EOI9.

Ensure that the reel
latch contains plastic
rollers.

Mods 3,
5, 7
B03
B05
B07

034

734469

New EOT/BOT
block modified for
better access to
cleaner blade. A
better photo diode is
also installed in this
new block. Picks
up E032. Replaced
by E051.

Check to ensure that
the EOT/BOT block
does not extend under
the flip-down mirror.

Mods 3,
5, 7
B03
B05
B07

035

905956

World Trade Only

---------

---

036

734288

50 Hz only. Prevents transfer valve
solenoid from burning up.

Ensure that the solenoid drops when the
pneumatic drops on a
load check.

Mods 3,
5, 7

037

734504

Installs 15 amp fuse
for F12 and F13 instead of lOA. Used
for -48V in left &
right reel motor.

Check for 15 amp fuse
in F12 and F13.

Mods 3,
5, 7

*Trademark of E. I. du Pont de Nemours & Co. (Inc)
107

3420 ECA CHECKLIST (continued)
Machines
Affected

ECA

E/A

Description

Checkpoint

038

734483

Increase ampere rating for F12 and F13
to 15 amp 50/60 Hz

Check for 15 amp fuse
in F12 and F13.

Mods 3,
5, 7
B03
B05
B07

039

734507

- Safety - insulate
-48V on interface
boards PIN 2515544,
2524666. (Picked up
by E048.)

Check for a clear or
rubber coating over land
pattern on power interface board for the modified power supply from
J3-K to J5-B.

Mods 3,
5, 7
B03
B05
B07

040

734506

EfA

Multiple sense output
and OVUV card EC
136690. Essential on
new build Mod 7, as
required on Mods 3
and 5. Prevents burning relay contacts on
reel motor boards.

Check for OVUV output Mods 3,
5, 7
card PIN 375478 and
multiple sense card PIN
375451 in all power
supplies.

041

734755

Vent vacuum columns Check for plastic insert
and prevents mini-reel in }2" vacuum column
loading problems
vent.
associated with ECA
E031. (composites
E031).

All

042

734754

Capstan cover holder

Check for holder inside
power door.

Mods 3,
5,7
B03
B05
B07

043

734470

Reduce exposure to
picked bit (dual
density only). Improve PE write
performance.

Check for EC 734470
stamped on dual density read cards.

Mods 3,
5,7

108

3420 ECA CHECKLIST (continued)
Machines
Affected

ECA

E/A

Description

Checkpoint

044

734762

High-speed rewind
plunger shim PIN
1847100. Allows
tape to clear read/
write head on a
thread or load operation.

Check for shim on
mounting screw for
HSR plunger.

Mods 3,
5,7
B03
B05
B07

045

734760

Select lamp noise
problem. Change
lamp and add 150
Ohm - 2W res on
output of lamp
driver. Helps eliminate velocity checks
and missing load
point.

Check for a 2-watt
resistor located on
wiring side of MST
board from
01A-A1J2B04 to 01AA1J2D08.

Mods 3,
5, 7
B03
B05
B07

046

.734741

New ceramic cleaner
blade design helps
eliminate loss of
amplitude due to
tape demagnetization
and reduces 237
abends due to contamination.

Check for a white
ceramic cleaner blade
PIN 1848197.

Mods 3,
5, 7
003
B05
B07

047

734763

Vacuum switch lead
insulation. Eliminates intermittent
shorts (dropping
ready) caused by
leads shorting to ac
ground.

Check for parallel
vacuum switch insulator
between vacuum switches and mounting plate.

All

048

734532

Solder the slip on
blade connectors on
the power interface
board. Decreases
power checks. (Composites E039)

Check for rivets soldered to the lands on back
of the power interface
board. (Modified power
systems only)

Mods 3,
5,7
B03
B05
B07

109

3420 ECA CHECKLIST (continued)
Machines
Affected

ECA

E/A

Description

Checkpoing

049

734945

F.O.lamp bracket to
improve light output decreasing equipment checks.

Check for 45 degree
bracket holding fiber
optics lamp.

Mods 3,
5, 7
B03
B05
B07

050

735881

PS logic - replaces
parts catalog on
power supply.

Check for EC 735881
on power supply logic

Mods 3,
5, 7
B03
B05
B07

051

734941

EOT/BOT block
W/O bundle (replaces E034)

Refer to ECA E034
checkpoint.

All

052

735643

Model 7 power door
lower glass safety
retainer. (This
glass may be installed on a Model
3 or 5 also.)

Mod 7 with vertical
plastic retainers, as
opposed to metal, holding lower glass in power
door. Check for metal
retainer under plastic
held by second and
fourth screws on each
side.

Mods 3,
5, 7
B03
B05
B07

053

734952

Modify the unload
sequence to speed up
the power window
operation on 3420
Models 3, 5, and 7

Check for wire from
01A-A1B2P09 to 01AA1E2G07.

Mods 3,
5, 7

054

734953

Decrease velocity
checks and start tach
failures by increasing
capstan motor low
power drive.

Check that R19 on the
capstan motor PCB is
a 25 Ohm resistor on
3420 Models 3 and 5
or a 15 Ohm resistor
on 3420 Model 7

Mods 3,
5,7

055

734956

Eliminate mechanical noise caused by
the file protect pin
hitting a file protect
sensor on some tape
reels.

Check for a recessed file
protect plunger.

Mods 3,
5, 7

110

3420 ECA CHECKLIST (continued)
Machines
Affected

ECA

E/A

Description

Checkpoint

056

734874

EC, ECA, Feature
Identifier List

None

Mods 3,
5, 7

057

---

World Trade Only.

--------

---

058

734949

Improve read reliability on tapes
written on some
OEM equipment.
Modified 7 -track
read card.

Check for EC 734949
stamped on 7 -track read
card.

Mods 3,
5,7
with
7-Track

059

734954

Decrease exposure
to lost records when
sensing voids in tape
in a backward operation. By removing
the early BOT sense
latch.

Check for wire from
01A-AlL2G09 to
01A-AlL2Gll

Mods 3,
5,7

060

736028

Increase air bearing
pressure to allow use
of back coated tape
for 3420 Model 7 PE
only.

Check for a red transparent pressure manifold.

Mod 7
Only

061

735811

System update for
factory only on 'c'
exit. Mandatory
factory only.

3420-4,6, and 8 check
AlF2 card for 8237074
PIN.

Mods 4,
6,8

062

736036

Provide correct Ioca- 3420-8 - open vacuum
tion of capstan motor column door and check
removal instructions. for a label on the capstan stating "caution".
See MLM 08-090, 08100, and 08-110.

063

736803

Remove filler block
from actual interference.

3420-4,6, and 8 - check All
for an "X" molded into 4,6,8
the filler block just to the
left of the R/W head.

064

736932

Power logic update

3420-4,6, and 8 - check
logic page YF036 for
EC736932.

111

Mod 8
Only

Mods 4,
6,8

3420 ECA CHECKLIST (continued)
Machines
Affected

ECA

E/A

Description

Checkpoint

065

735813

Provide zero threshold in 1600 bpi read
operation during data
portion of record.

3420-4,6, and 8 - check
01A-A1K2 for PIN
8237090.

Mods 4,
6,8

066

906196

World Trade Only

--------

Mods 3,
5, 7
B03
B05
B07

067

736819

Improved reel tach
asm

3420 all - remove left
or right reel tach and
look for white dot on
the bottom of the
housing.

Mod 3,
5,7
Mod 4,
6,8

068

735815

Cancelled

--------

---

069

736031

Cancelled

--------

---

070

736828

Prevent unload failure due,to false not
tape present indications.

3420 all - check for a
capacitor from 01AAID2B09 ( +) to
GND(-).

All

071

736992

Prevent transistor on
write card from shorting on cartridge
motor casting.

3420-3,5, and 7 - remove front head card
cover and check for
foam strips inside of
the cover.

Mods 3,
5, 7
B03
B05
B07

072

735635A

Install II 0 connectors (ESD problem)

3420-4,6, and 8 - check
for plated I/O shoes on
drive.

Mods 4,
6,8

073

735817

Prevent "Not
Capable" OK on ftrst
Cmd after "load-op"
due to auto-cleaner
ribbon still on head.

Load drive and hit start
before tape reaches LP.
There should be a delay
of about 3/4 sec after
LP is reached and ready
light comes on.

Mods 4,
6,8

074

736683A

Install latest level
logic page YC031.

3420-4,6, and 8 - check
YC031.for EC 736683A
or higher.

Mods 4,
6,8

112

3420 ECA CHECKLIST (continued)
Machines
Affected

ECA

E/A

Description

Checkpoint

075

735818C

Prevent loss of capstan control and add
Cmd tag reset.

3420-4, 6, and 8 - check
0IA-AIH2 card for PIN
8237044.

076

735166

Correct -4V regulator wire on power
supplies.

All Mods
3420-4, 6, and 8 with
piggy-back power supply of 4,6,8
check for wire No.1 of
cable PIN 1767877 on
TB-3-5 on front of the
power supply.

077

737013

Prevent intermittent
tape damage on unload op.

3420-3,5, and 7 - check Mods 3,
for PIN 8237109 in loca- 5, 7
tion 0IA-AIG2.
B03
B05
B07

078

733222

Eliminate MISSplugging of the read
cables on the read
card.

3420-4,6, and 8 - check
for label on read cable
saying "Rd Card Rear."

Mods 4,
6,8

079

906326

World Trade Only

---------

---

080

443868

Fiber optic lamp
cleaning label.

Check for label attached
to MST card gate cover.

All

081

443862

Prevent piggy -back
power supply regulator diode failure
Model 416/8 supply

Check for la!ge power
Mods 4,
diode bolted to small
6,8
pre-reg card PIN 4169370
4169370 and connected
by external leads soldered to land. (See YF060
for location)

082

443870

Prevent transfer
valve relay RIC net·
work failure.

Check SCRA card
located inside ac panel
on which mainline CB
is mounted for orange
sprague "gumdrop"
capacitor. (.25J.LF600V)

113

Mods 4,
6,8

All

3420 ECA CHECKLIST (continued)

ECA

083

Machines
Affected

EfA

Description

Checkpoint

443864

Improved three-way
valve and filter deflector to eliminate
foil particles in pneumatic system.

Inspect three-way valve
attached to end of transfer valve for four screws
attaching manifold to
body.

All

084

443894

Model 4/6/8 field
adjustment procedure

No physical checkpoint
review IR history.

Mods 4,
6,8

085

443893

Rueger vacuum
switches eliminate
drop ready and
load failures.

Inspect switch positions Mods 4,
L1, L3, L4, R2 and R3
6,8 and
for round switches and
3,5,7
sliced cable connectors.
L2, RI, and R4 should be
square. (Some very early
drives may have all
round switches)

3,5,7
E
4,6,8

086

443890

Model 4/6/8 threeway auto cleaner
solenoid. Eliminate
PV valve and correct auto cleaner
operation.

Check for hose running
directly from rewind
solenoid to auto cleaner.

Mods 4,
6,8

087

443911

Eliminate Relay and
transistor failure on
power window
board.

Check for 47J.1F cap
attached in parallel to
resistor R12. See ALD.

All

088

---

World Trade Only

089

World Trade Only

-----------------

---

090

---

World Trade Only

---------

---

091

---

World Trade Only

---

092

---

World Trade Only

-----------------

093

---

World Trade Only

---------

---

094

443899

Provides plated I/O
cable connectors to
minimize ESD problems.

Check for plated I/O
connectors.

Mods 3,
5,7

114

---

3420 ECA CHECKLIST (continued)
ECA

095

Machines
Affected

E/A

Description

Checkpoint

449022

Replaces RC network associated with
transfer valve and
adds a new RC network in the same
circuit.

Check for RC network
(P/N 4169599) on the
solenoid contact relay
assembly (SCRA) card
in the A-C box.

All

096

449014

Eliminate drop
ready conditions
due to vacuum
switch failures.

Check for round (grey
color) vacuum switches
in positions Ll, L3, L4,
R2 and R3.

Mods 4,
6,8

097

443935

Prevent erasing a
good block during
error recovery on
a write operation
causing a 237 abend
on the next read op.
Also prevents a
possible start read
check by opening
gap control up
earlier.

Check for card PIN
8250221 in loc E2 and
8250220 in loc F2.

Mods 4,
6,8

098

---

World Trade Only

---------

---

099

---

World Trade Only

---------

---

100

---

World Trade Only

---------

---

101

449068

To provide a current
bypass for an intermittent connection
between heat sink
and land pattern at
the unregulated
portion of the 4 and
6-volts on the board.

Check for jumpers from
power Intf board terminal E12 to clip on the
lower heat sink and terminal E9 to upper heat
sink.

B03
B04
B05
B06
B07
B08

115

3420 ECA CHECKLIST (continued)
Machines
Affected

ECA

E/A

Description

Checkpoint

102

449087

Prevent tape dump
and drop ready
caused by inc orrectly installed mod
wires on the tape
drive logic boards.
Also corrects failures on conversion to Mod 4 or
6 from Mod 7 or
8.

If reel motor boards
are PIN 373561 or
PIN 2524137, no wire
B2B12 to B2P10. If
other than PIN
373561 or PIN
2524137 there should
be a wire from B2B12
to B2PIO.

Mods 4,6

103

845992

Corrects power
window circuit
board failures.
Replaces capacitor
C3 and relay K8.
This EC replaced
ECA 087.

Capacitor C3 on the
power window circuit
board at 100 JlF

Mods 3, 5,
7,4,6,8
WTC
Only

104

449092

Help prevent reel
motor board failusers by decreasing
a voltage spike that
burns out transistor
Q8.

Installs a diode across
the HS rewind solenoid.

Mods 3, 5

105

846015

ECA reserved for the
replacement of the
cartridge retaining
button. Released
for recording of
time and parts.
Cannot be ordered as
EC.

Cartridge retaining
button should be black
in color. If not, order

All

Decrease reel motor
circuit board failure.
Installs 1.3 ohm reel
motor current limiting resistors.

1.3 ohm resistors in the
reel motor and capstan
motor resistor assembly.

106

449093

116

PIN 4169428.

Mods7,8

MODELS 3, 5, 7 .. Al BOARD

J
FT45X

FT26X
Rewind

FT231

FT28X

Connector
Gated
Ready

Thread
Status
Photo
Detection

FT35X

Load
Point
Status

Load
Check
Tape
Present

PushButtons

Connector

FT39X

Load
Op

Load
Complete

Connector

FT11X
Status
Multiplexing
0-7

Load
Rewind

Cartridge
and Door
Interlock

Capstan
Control

Unused

Capstan
Drive

Columns
Loaded
and
Unloaded

Window
Up/Down

Unload
Complete

Pneumatic
Drive
Cartridge

Unused

FT70X

Interface
Bus-In
Connector

Interface
Decode

Write
Fail
Detect

Write
Select

Write
Deskew
P,0-7

ID
Gating

Read
Select

Manual
Status
Control

Air
Pressure
Detection

Unused

PowerOn and
Sense
Resets

Write
Current
Control
FT10X
Write
Data
Gating

Sense
Decode

Interrupt
Generation

Sense
Byte
3,4,5
Decode

Read
Deskew

(~~i'
Feature,I
Only

Bus-Out
Tag-Out

Connector
Tach/
Busy

Sense
Level
Control

Unused
Metering

IBG
Control

Connector

Unused

TCU
Interface

FT14X

Connector

Reels
Loaded
4

FT60X

Terminator

Backward

Connector

FT13X

Write
Status
Drive

Erase

Reel
Control

Connector

Unit
Check

Degauss

Mech
Ready

EOT

Loop

Unused

Gatin~

Unused

Offline
Relay

Unused.

Unused
7

117

MODELS 4, 6, 8 - At BOARD

Cartridge
Switches
Connector

t
FT45X
Capstan
Control
(Rewind)

FT26X
Rewind
Gated
Ready

Air
Bearing
Pressure
Switch

FT231

Connector
FT34X
Capstan
Control

FT33X
Capstan
Control

Photo
Detection

Load
Complete

Auto
Cleaner
Control

FT30X
Capstan
Control

Connector

Write
Select
IBG
Counter

Reel
Control

Cartridge
and Door
Interlock

4
Connector
Vacuum
Switches

Columns
Loaded
and
Unloaded
Unload
Complete

Connector

FT13X

FT28X
Cartridge
Controls
Window
Up/Down

FT18X
Zero
Threshold

Forward
Hitch

Load
Point
Status

Erase
Status

Write
Data
Gating

Read
Select

Interrupt-In
Bus-In

Write
Status
Drive

Tach/Busy

Sense
Decode

Read Data

Power-On
& Sense
Resets

Sense Byte
3,4,5
Erase
Decode

Density
Select

Crease
Tape
Control

Sense
Level
Control

Status
Bus

Air
Pressure
Detection

Mech
Ready

Unused

FT31X
Capstan
Control

Metering
Feature
Jumpers

Interrupt
Generation

Unused

FT10X
Tape Unit
Bus &
Tags
From
TCU

ROS

FT910
Offline
Relay

Unused

119

Unused

Conn
(Auto
Clean)

Unused

Tach Pulse
Counter

Reels
Loaded

Bus-Out

Tape Unit
Tester
(Pin Side)

SAGC
Check

Connector

Load
Rewind

Load
Check

Connector

Tach/Busy

EaT
Unused

Connector

Loop
Gating

Degauss
Manual
Status
Control

Interface
Bus-In

FT11 X
Status
Multiplexing
0-7

Unit Check

5
Vacuum
Switches

FT14X

ID Gating

Write
Current
Control

Capstan
Control
Reel
Control
(Rewind)

Polarity
Hold Drive
Register

Thread
Status

Terminator

PushButtons

Reel
Control

FT32X

Connector

Interface
Decode
Proportional
Drive
Counter

EaT/BOT

CARD JUMPERS - MODELS 3, 5, 7

r.-;-;---;-;-;;

.---1

I ••
I•
···

I.
• •• 1..---- EC
1• •
1
, ••• I

···1.···'
••••

I • • •
I. • •

• • • I
• •• I
I • • •
• • • I
IL •________
• •
• •• 1

..J~

I... ,- .

Level

r;-;-;1

Features

l... _ _ _ J

Serial Number

IModj
-Component SideA1 L2 Card
Connector Edge
Reference Logic A61 06

o
......
......
• .....
......
......•
.....
1

......
......

o
......
......
1

256
512
1024
2048
4096
8192
• 16384
• 32768, •

......
......
.....
.......
.......
.....

1
2
4
8
16
32
64
128

Serial Number
• Multiply Model Number Times 10,000
(Example: Model 3 x 10,000 = 30,000)
• 'Subtract Number Found Above From
Serial Number (Example: Serial No.
37350 - 30000 = 7350)
•

Plug for Remaining Number in Step Above
(Example: 7350)

•

PI ug All Other Bits to 0

121

CARD JUMPERS - MODELS 3, 5, 7 (continued)
A B
.....
F2......... • ~~--Example: NRZI
F1~·

A B
.....
E2~"'" .~Example: EC734030
E3~"'" •
E4~"'" •
E1~

Features
F1

Basic

NRZI

7-Track

EC Level

123

EC 733999

EC 734030

CARD JUMPERS - MODELS 4, 6, 8

(

EJ 8

Old Model

~~f~~eer

Module

Conversion}

r---:1

r---------:1
I • • •
I • • •

•
••
••
••
1......--EC
Level
•• ••
1 I•
•1
1 1• • • 1
• • • 1 L ____ J

. ..

• • •

I • • .' I . . .
• I
~• • _I

I···

··1

1
:-.-;-;1 I...
I...

• •• I r----l
•••

I• • •

I • • • I~Features

• • • I

I· • •

• •••

L ___ .J

~--------~~

I I I I
Module

Module

~~~~r

-Component SideA1 L2 Card
Connector Edge

n---------n

I
2

I Model 8
IgggC~-~I! ~ ~
J3

Models
4 and 6

I [DJ

Write Head Card
Component Side View

Model 8

Models
4 and 6

Write Head
Reference Logic A6106

125

CARD JUMPERS - MODELS 4, 6, 8 (continued)

o1
.....
256
.....
512
• .... 1024
• ..... 2048
• ..... 4096
...... 8192
...... 16384
..... ·32768

o1
......

......

Serial Number
• To plug Serial Number Use Following Formula:

......
4
Serial Number
} Example:
......
8
- '10,000 x Original Model No.)
For Serial Number
...... 16
37485
• ..... 32
= Number To Be Plugged
(Originally Model 3)
...... 64~
..... • 128
----..... Example
37485
Serial No.
Plugged ~30000
Plug all Bits Either 0 or 1
10,000 x 3
7485

to be Plugged

A 3
......
C2~ ...... ~Example:
C3~..... •
Model 5

Old Model Number
• Plug Original (Before Conversion) Model Number:

A B
.....
E2~ .....
E3~ .....
E4~ .....

EC Level
Plug E1 Through E4 to A (As Shown) for
EC 735810 or Higher

C1~

E1~

•
•
•

Old Mod
3
4
5
6
7
8

C1
B
A
B
A
B
A

C2
A
A
B
B
A
A

C3
B
B
A
A
A
A

~----.

•

A B
F1 ~. ..... ~ Example Shows
F2~..... •
6250/1600

Features
• Plug as Follows:

Basic
6250/1600

127

F1
A
B

F2
A
A

COMMON 3420 PART NUMBERS
Pneumatic Belts

\i1ti----2

Part No.

Model

(1)

1767004
1765850
1767005

3,4,5,6
8
7

26.38
25.59
27.95

(2)

2522882
1765854
Note:

3,4,5,6,7,8
8

20.28
19.69

If pneumatic belts come off do not reinstall- use new belt. When installing new
belts do not roll them onto pulleys. Loosen motor or pump to install new belt.
Use procedure described in maintenance documentation.

129

COMMON 3420 PART NUMBERS (continued)
LOW ALTITUDE

*See Note 13
Chart B

Chart A

8492814

(ill

2496287

8492806

2496287

8492818 Blower ~
Note

[ill

[g]

[]@J

8492811

8492819 Blower
Note

0 §] 0 0

Belt PIN

Note

Pulley PIN

[D
[]

8492813
8492810

2496303
2496303
8492977

Note

@]
[@
@] ~
[]
II]

Notes
Pully must be seated against shoulder of the pump
shaft

8492823 Motor Asm
Note

ITD

[i]

B/M 8492827 60 Hz (Mod 3, 4, 5, 6)

8492822 Motor Asm
Note

[3J E2]

B/M 8492829 50 Hz (Mod 3, 4, 5, 6)
Elbow nears IDE pointed away from the casting

8493010 (2x)
Idler Arm Asm

Preliminary performance at 750 F (23.90 C) and
25.00 inches (635 mm) Hg for B/M 8492827 and 8492829
vacuum 21.70±1.50 inches (551.2 ± 38 mm) H20 at 16.70
+1.50
SCFM (472.89DM 3 M) pressure 5.00-0.00 SCFM
(141.58 + 42.48 DM3M) at 2.50 PSIG (0.0018 KG/MM 2 )
for B/M 8492835 and B/M 8492337 vacuum 35.00 ± 1.50
inches (889 ± 38.1 mm) H 0 at 36.50 SCFM (1033.57 DM 3 M)
2
+2.00
Pressure 5.00-0.00 SCFM (141.58 + 56.63 DM 3M) at 2.50
PSIG (0.0018 KG/MM2) for B/M 8492831 and B/M 8492833
Vacuum 27.80 ± 1.50 inches (704.1 ± 38.1 mm)
H 20 at 19.30 SCFM (546.52 DM3M) pressure
+2.00
5.00-0.00 SCFM (141.58 + 56.63 DM 3M) at 2.50 PSIG
(0.0018 DG/MM2)
Either 1765057 filter or 1765653 filter can be used interchangeablv
Bond with I BM specification 1703 adhesive

149908 (4x) SCR

2515538 Compresso'r--------t..J

Note
496272

Note

(2x) Post

[ill

[g]

146327 (4x) SCR
Note

[TI

E2]

Note

[i)

B/M 8492835 50 Hz (Mod 8)

'~"-..

B/M 8492837 60 Hz (Mod 8)
/

9092 LCKW Ref

"-.._~~ 332620 SCR Ref

8492820 Pulley
Note

OJ 0

B/M 8492831 60 Hz (Mod 7)
B/M 8492833 50 Hz (Mod 7)

~~,
8492838 Flat Belt

Initial deflection on belt should be .100 ± .030 (2.54 ± 0.76)
when idler is contacting belt

Refer to MLM for high altitude.

•

-----8493010 Idler Arm Asm Ref
2496296 (2x)

12015 Key

Note

2522905 Set Screw

2496300 Spring Ref
8492824 Casting

FLAT BELT PNEUMATIC SUPPLY

131

[FE12830

COMMON 3420 PART NUMBERS (continued)

'''''---2

Part No.

Model

(1)

1847949
1765551
2515350

3,4,5,6, 7,8
3,4,5,6,7,8
7,8

39.37
39.37
40.55

3,4, 5, 6, 7,8
3,4,5,6,7,8

19.17
20.28

(2)

2512762
2522882

BM =Bottom Mounted Motor
Note:

If pneumatic belts come off do not reinstall- use new belt. When installing new·
belts do not roll them onto pulleys. Loosen motor or pump to install new belt.
Use procedure described in maintenance documentation.

133

COMMON 3420 PART NUMBERS (continued)

Part No,

Model

(1)
1766517

3,4,5,6,7,8

35.43

3,4,5,6, 7,8

17.72

(2)
1765657

Note: When installing belts, use procedure
as described in maintenance documentation.

The following B/Ms are required when changing altitude with a
flat belt pneumatic supply.
3420
Models

Altitude 60 Hz
Above
0-4000
4000

Altitude 50 Hz
Above
0-4000
4000

3-5
7
4-6
8

8493017
8493018
8493017
8493018

8493022
8493023
8493022
8493024

Note:

8493015
8493016
8493015
8493016

8493019
8493020
8493019
8493021

If pneumatic belts come off do not reinstall - use new belt. When installing new
belts do not roll them onto pulleys. Loosen motor or pump to install new belt.

135

COMMON 3420 PART NUMBERS (continued)
Reel Motor and Reel Motor Board Part Number Combinations
POWER SUPPLY
2522840 (60
. 1767836 (60
2515413 (60
2515421 (60
1767917 (60
1767835 (50
2522839 (50
2522465 (50
1767918 (50
1766046 (50

Hz)
Hz)
Hz)
Hz)
Hz)
Hz)
Hz)
Hz)
Hz)
Hz)

2522838 (60
2515367 (60
1767834 (60
2515410 (60
1767850 (60
1767833 (50
2522837 (50
2524644 (50
1766045 (50
1767849 (50

Hz)
Hz)
Hz)
Hz)
Hz)
Hz)
Hz)
Hz)
Hz)
Hz)

REEL MOTOR

BOARD

I
2513168 LEFT ~ - - - - - 373561-~
1765047 LEFT
2523744 RIGHT
2523744 LEFT--[[)

~----

2524137

2513165
1765389
1765390
2513074
1765390

~----

373065

I
LEFT
LEFT

LEFT-~
RIGHT
RIGHT

Note

Motor (PIN 2513168) and board (PIN 373561) must be used together
and only with each other.

Note

[I]

WTC Only.

Notes

C and

D (Applies to all PINs)

3420 drives with high-speed reel motor
boards PIN 373561 or PIN 2524137'
must have wires B2B 12 to B2P10 and
B2B 13 to B2P13 removed. Other
motor boards require that wires B2B12
to B2BP10 and B2B 13 to B2P13 be
installed. Problem may show up as
dropping ready andlor dumping of
tape.

136

COMMON 3420 PART NUMBERS (continued)
Capstan Motors
Part Number

Model

1766960
1766761
1846689
1766700
1845857
2522864

3, 5, 7 (9XXXX series)
4,6
4,6 (9XXXX series)
8
8 (9XXXX series)

3,5,7

Transfer Valve - Three-Way Valve and Manifold Assemblies
Valve & Manifold Asm PIN
4169448
4169449
4169450
4169451

Manifold Color
Grey
Black
Green
Red

Model
7 NRZI
7 PE 3,5
4
6,8

If the 3420 was ever NRZI or had EC 736028 installed on a Model 7 due to use of backcoated tape, the red manifold must be used.

3420
Piggy-back Supply - BOX Series (9XXXX Serial Numbers) and 34090 to 37099
Interface Board

- PIN 17678694/660 Hz (used with 176850 supply)
PIN 1767868 All other 50/60 Hz
PIN 2515544 9XXXX, 34090, to 37099

Pre-regulator

- PIN 4169370 (was 1767871)

137

3803

3803 MODEL 1 DATA FLOW
Write
Heads
Bus-Out

Out
Reg

Write
Reg

TUBa
Write
TGRS 1----+

A1J2

A1G2

Write
Drivers

'1\
~

Bus-In

TUBI . Read
In
Reg

Aux

Ecc

Skew

Reg

A1D2

BFR

A1J2

A1D2

Microprocessor Card Locations
MP1

MP2

ALU

B2C2

A2N2

RDS

B2H2

A2H2

RDS Reg

B2D2

A2M2

B2E2

A2L2

Clock

B2F2

Instruction
Decode

B2D2

A2M2

LSRs

B2C2

A2N2

Xout A

A2T2

A2Q2

Xout B

A2T2

A202

D-Reg

B2C2

A2N2

139

III

3803 MODEL 2 DATA FLOW
See MLM 50-XXX for more detail.

A RD Bfr
1 x 9 A1C2
WR
VRC

B RD Bfr
1 x 9 A1C2
CH Bus
A1F2
Write
Byte
Bfr
1 x 9

Chan
Bfr
A1F2
32 x 9

Chan
Bfr
Gate
A1G2

Write
Group
Bfr #1

Write
Group

4 x 9

A1H2

Bfr~'

Write
Encode
A1H2

Serial
by
Byte
A1H2

Write
TRG
A1H2

1 x 9

CRIC
CROC

Fon:nat
CTRL
A1G2

~t>
~t>
RD

ECC
Bfr
Y1G2
1 x 9

Xlator
Y1K2
Y1 L2
Y1M2

Group
Bfr
Y1K2
Y1 L2
Y1M2
5 x 9

Skew
Bfr _
Y1K2
Y1 L2
Y1M2
32 x 27
RIC

Pointer

141

ROC

Ones
PE 0 ER

o ER

VFC
Y1R2
Y1S2
Y1T2
1 x 9

3803 MICROPROCESSOR INSTRUCTION FORMAT
Microprocessor instructions have the follOwing format:
[label] OPCODE fieldl, field2 [comments]
label is a one to eight-character name by which the instruction can be referenced. Branch
instructions point to locations in the microprogram by label.
OPCODE is the operation to be performed on the data or addresses in Field 1 or Field 2.
Field 1 is generally an address in the Local Storage Register. In some instructions this
field may be a branch condition or ROS page number.
Field 2 is generally a constant, referred to as a decimal number or by a symbolic name.
The value of symbolic constants for each microprocessor is listed in the beginning of the
listings as EQU statements. In some instructions this field may be a branch address or
transfer code.
Field 2 can contain several symbolic constants combined arithmetically, that is, the sum
or difference of two or more constants.
For example, the constant in the instruction:
ADD WORK1 ,ONES-174
results in the constant hexidecimal FF (ONES) minus the decimal value 174, or a decimal value of 82.
For more detail see MLM 52-030.

143

3803 MICROPROCESSOR TIPS
ROS Patch Card
The ROS Patch Card, part 8215414:
• Allows emergency repair of defective ROS words. (In this application, the card allows
reconstruction of a ROS word that has a single defective bit.)
• Allows application of an emergency REA to the microcode, until production of a new
MST-A card can support a field bill-of-material.
• Serves as a diagnostic tool.
This card plugs into A2G2 for MP2, B2J2 for MPI.
Reference MLM 80-030 or PF for a description of patch card plugging.

Microprocessor Card Interchange List
The following is a list of cards that can be interchanged between ALUs.
ALUI

ALU2

B2C2
B2D2

A2N2
A2M2
(watch for feature jumpers)
A2L2

B2E2
B2F2

A2K2

The following is a list of cards that can be interchanged if the two-channel switch feature
is installed:
CAUTION:

B2Q2
B2R2

RemOving these cards may cause channel errors, even with power off. Put
CPU in single cycle mode before removing cards.
with
with

B2P2
B2S2

145

3803 MICROPROCESSOR TIPS ( continued)
To Determine the Failing Instruction Address
The best way to get the failing address is to stop the ALU on the error. To do this, turn
the Control Check Switch to the ON position. See Stop Procedure on 12-010, Seq 3.
When the ALU stops, the Instruction Counter contains the address of the next (sometimes second) instruction to be executed. Remember that the Instruction Counter and
the ROS Register are updated during the execution of the failing instruction.

It is possible that some red light errors are the result of a failure that took place several
instructions earlier. For example, bad parity can be stored in an LSR and not be caught
until the LSR is read out. This situation results in a B-bus parity error, but the real problem exists with the action that loaded the LSR or the LSR itself.

To Make the ALU Loop on an Error
There are two positions on the ROS mode switch that can be used to make the ALU
loop: the RST/ERR and RST/CMPR.
If the RST/CMPR position is used, the ALU is reset before the instruction at the compare
register address is executed.
The RST/ERR position gives a better loop in most cases. When the RST/ERR position
is used, the instruction executing during the error is completed before the general reset.
It may be necessary to add a jumper from GENERAL RESET to the CE START LATCH
(B2Q2S10 to Al T2G05) if an I/O operation is included in the loop. The jumper is not
needed if the error occurs during ALU checkout or IDLESCANS.
See MLM 16-000 for more detail.

General Reference Information
The following items should be kept in mind when troubleshooting a microprocessor
problem:
• The COMPARE EQUAL line (AI U2U07) goes minus just before the execution of the
instruction. The stop-on switches must be OFF to allow a compare .

• If the failure is at address 000, RESET or TRAP ALU2 (A2K2DIO, AAOll) is a good
sync point.

146

3803 MICROPROCESSOR TIPS (continued)
• When displaying ALU execution on the scope, make sure that a complete cycle is
shown. The 0 ns taps for the ALU are:
ALUI B2F2G 12
ALU2 A2K2G 12
• BU, BOC, and ADD instructions require a long cycle, 200 ns. All other instructions
execute in a short cycle, 150 ns.
• Slow fall time of a pulse might be caused by a missing external load. Check the tape
control ALDs for their locations.
• Always remember that you are troubleshooting lines as well as cards. If you find a
bad net and the card or cards driving the line have been ruled out, something else must
be wrong within the net.
• If an I/O command is involved in troubleshooting a problem offline, a contingent connection might occur .. This condition is apparent if ALUI stops with address 301 in
the instruction counter. To breal<. the connection, follow each failing command with
a sense command.
• Random ALU failures can be caused by the ALU oscillator card, Al H2.
• Use the timing charts for a better understanding of an operation, as well as reference
when a timing check is called for. Timing chart is on 16-001.
• If cards are changed and the outputs are still bad with good inputs, check for proper
voltages at the card socket.
• The CE panel lights indicate the ROS data bits, not the ROS register bits.
See MLM 16-000 for more detail.

147

CURRENT ALU PATCHES
3420 Models 3, 5, 7 - 3803 Modell Tape Runaway
**SYMPTOM**
When initial read is given (open, etc) the tape appears to run away. It occurs every time
the failing reel is mounted. 3803 has NRZI capability. This runaway will not occur on
PE only 3803.
**PROBLEM ISOLATION AIDS**
If account has 6250 bpi drives or the failing tape could have been written in 6250 bpi
mode, develop the tape to see if it has been written in 6250 (ID burst will be in track 1
if 6250). If you find 6250, a patch to ALU 2 can be applied to eliminate the problem.
This patch is a four-word patch which tests for IBG (all tracks down) anytime the P-track
is tested and not seen. If no IBG, a 6250 tape is assumed (track 1 active) and not capable
is set.
**FIX**
The ALU 2 patch works as follows. (W/O 7-track drives attached):
Word 0000
A001
Bump Counter
Word 0001
6053
Return
Word 0010
2FOO
BOC IBG, 0000
Word 0011
6048
Return to Set Not Capable
*******PLUG PATCH CARD AS FOLLOWS*******
1---P
6---A001
ll---N
2---1
12---6048
7---N
3---0
8---6053
l3---R
4---0
9---R
14---0
5---052
10---2FOO
15 through 23 not applicable.
As this patch requires only four words, the four words on the other side of the patch
card can be used for velocity, etc.
**** The following fix is for 3803 with 7-track drives attached. This patch is not
effective against mounting a 6250 written tape on a 7-track drive. If mounted, the
tape will run away. No fix for 7-track is available.**************************

149

CURRENT ALU PATCHES (continued)
Word 0000
3003
BOC D-Reg Position 0 Equal 1, 0003
0001
6057
Return (Set Not Capable)
0002
Not Used
0003
6056
Return (Good NRZI Tape)
0004
6058
Return (No ALU Carry)
0005
2104
BOC NALCO,0004
0006
2F03
BOC IBG ,0003
0007
D780 And, Sense Status 1, Seven-Track
------PLUG PATCH CARD AS FOLLOWS-----1.
2.
3~

4.
S.
6.

P
0
0
0
055
3003

7.
8.
9.
10.
11.
12.

N
6057
R
N/ A
N/A
6056

13.
14.
15.
16.
17.
18.

R
0
N/A
6058
R
2104

19.
20.
21.
22.
23.

N
2F03
N
D780
N

Excessive Postamble Error

**SYMPTOM**
Excessive postamble error on specific tape. Error every record.
**PROBLEM ISOLATION AIDS**
Tape reads error free on 2803 and may on 3803 Mod 1. 2803 does not check postamble
length on a read. 3803 Mod 1 allows about 49 zeros while the 3803 Mod 2 allows about
45.
**FIX**
Locate and fix the control unit that created the tape containing the records with excessive postamble. If the customer library is badly contaminated with these tapes, and it
becomes necessary that the tapes be processed on a 3803 Model 2, a patch can be
applied to ALU2 via the patch card. Change the instruction at location OOOOAO from
09E7 to 09XX. XX being the count field. For example, to increase the count by five
bytes, make the count E2 instead of E7.

150

CURRENT ALU PATCHES ( continued)
Lost Device:'End - Unexpected Interrupt

**SYMPTOM**
Customer indication - allocated and busy and nothing is happening on the drive, console
indicates lost device-end, usually for drive 0 or 4, failures so far have occurred on systems
with 3803 2X8, 3X8, or 4X8 configuration. Fails when system tries to stack channelend after a rewind and interrupt buffers full. Microcode eventually resets drive address,
drive 0 committed. Latch will be set, and drive 0 will end up, busy until software times
out and indicates lost device-end. Also have contingent connection.
This patch may be applicable to 3158 and 30XX systems.
**PROBLEM ISOLATION AIDS**
Install CE latch to test for the following conditions
'AND' A2R2PI0 (FD041) with AIU2U07 (PP021) to set indicator.
Use compare address of 02E4 for 3803-1 or 02DD for 3803-2.
If indicator is set, install following fix to ALUI.
**FIX**
3803-1
3803-2 --

Address 02E4 -Address 02DD --

Put unconditional branch to next inst
Put unconditional branch to next inst

Also see:
Temporary Reads in 6250 Mode.
Extend Velocity Retry Time. .

.
.

. 3803 ECA III
. 3803 RPQ S10112

Settling Time/Write After Read (ALU 2)

Change Loc 744

VER 0089
REP 0083

Delay write trigger turn on by 6 or 7 tach pulses. Affects 613 ABENDs
3803 Model 2 only.

151

CURRENT ALU PATCHES (continued)
Turnaround Delay (ALU 2)
Change Loc 15B

Ver 3480 (Mod 2)
Rep 615C

Adds 11.16 J.lS of time. Error is. unexpected load point.
Postamble Patch (ALU 2)
Change 2B6

Ver 00D8 (Mod 1)
Rep GOD7

Allocated Busy (ALU 1)
Change 02£4 to unconditional branch to next instruction. (Mod 1)
Change 02DD to unconditional branch to next instruction. (Mod 2)
yelocity Patch

(RPQ S101l2)

3803 - Mod 1

I---P
2---0
3---0
4---0
5 - - - 202
6---N/A

7---N
8 - --N/A
9---N
10 - - -1300
ll---N
12 - - - 6203

13 ---R
14 through 23 not applicable

7---N
8 - - - 6215
9---R
10---N/A
I1---N
12---N/A

13 - --N

3803 - Mod 2

I---P
2---1
3---1

4---0
5 - - - 214
6 - - -1300

14---0
15 - - -7B9
16---N/A·
17 - - - N
18 - - -1500

152

19 - --N
20---67BA
21---R
22---N/A
23 ---N

CURRENT 3420/3803 RELATED SOFTWARE ZAPS
Allow 3803 Sense After Selective Reset (TSI1614)
When the 3803 detects an ALU check, it raises disconnect-in. If it is plugged for
370 operation, this in turn causes an interface control check in the CPU, which signals
the CPU to do a selective reset to the 3803 TAU, as it may possibly be hung. The program then will not do a sense command to the 3803 to see where the error was located,
as the sense information was supposedly destroyed via the selective reset, which architecture calls for. However, the sense information in sense bytes 11 and 12 have been
reserved by 3803 engineering, and these two sense bytes tell what type of equipment
check it was originally.
The CE can do one of two things. First, have the customer run the 3803 in hard stop,
to see what kind of error it is, but this would probably be disastrous to the customer.
Or else, he could apply one of the following three zaps to EREP so that EREP would do
a sense and print out the sense bytes, thereby telling what type of error existed. The
MVS and VS1 zaps have been tested at the stated levels correctly, but the zap for SVS
has not been tested, but should work okay. Be sure and remove the zap after you determine where the error is from EREP printout.
MVS Zap for Release 3.7 PTF Level UZ08355
Module IGEOOOOI
Tape 7701 or 7706
Label D300 is Right Before Address ABC, for Ease of Finding A8C
VER A8C 4780 F5EE
Branch to Return
REP A8C 47FO FE04
Branch to Patch
REPE04 4710 FA90
Branch to Logout if SDR O'Flo
REP E08 9120 A020
Test for Bus-Out Check
REP EOC 4780 F5EE
Branch Zero to Return
REP E10 9601 1001
Turn on lOS Log Bit
REP E14 47FO FA90
Branch to Logout
****End of MVS Zap*** This Zap Tested OK on MVS R037
SVS Zap Release 017E - - Not Tested at R017E
Module IGE0300I
VER 31A 9103 A008 4770 F32C
VER 3A4' 0008 OOOA 0000
REP 31E 47FO F3AA
Branch to Patch
Test
O'Flo Log Bit
REP 3AA 9103 A008
Test Sense Byte 0 Bus
REP 3AE 4770 F32C 9120 A002 4780 F322
Out Check. Branch NU to
9601 A008 47FO F32C
Error Exception or IMM.
Branch to OBR.
**** End of Zap**** Not Tested at SVS Level R017E.

153

CURRENT 3420/3803 RELATED SOFTWARE ZAPS (continued)
VSl Zap Tested for Release 050 and 060
Module IGE03001
VER
32A
4710
F33A 9103
A008 4770
VER
3B8
0008
OOOA 0000
REP 332
47FO
F3CO
F340
9120
REP 3CO
9103
A008 4770
4780
F336
9601
A008 47FO
*** End of Zaps*** This Zap Tested at RO~O and R060.

154

F340

A002
F340

3803 CHANNEL INTERFACE
System/370 Disconnect In - MP Hardware Error
3803 In Idle Scans - ALUI or ALU2 Error
1.
2.
3.
4.

Disconnect in raised after op-in on next channel initiated sequence.
ALUs trap and restart the idle-scan loop. The error is saved in ALUI local storage.
Unit check is presented in initial status of next SIO/TIO if not a sense command.
Bus-out check is set at sense time if the control unit is holding ALU error and no
other bit is on in sense byte O.

3803 Connected to the Channel
ALU2 Error:
1.
2.
3.

Unit check is presented in initial status of next SIO/TIO if other than a sense
command.
Disconnect in will not be enabled.
Bus-out check will be set at sense time if no other bit is on in sense byte O.

ALUI Error: (W/O ALU2 Error)
1.
2.
3.

Disconnect-in is raised and an interface control check results. (Channel issues
selective reset.)
Unit check is presented in initial status on next SIO/TIO if other than a sense
command.
Bus-out check will be set at sense time if no other bit is on in sense byte O.

Channel Errors Caused by "Disconnect-In" From 3803
3803-1,2- Service Aid 5
The 3803 Models 1 and 2 present "disconnect-in" to the channel under either of the following two conditions provided "disconnect-in handling" is wired active (S/370 - see
Installation Manual).

1.
2.
Note:

Any time an error (sense byte 11) occurs in ALU1.
When an error (sense byte 12) occurs in ALU2 while ALU2 is in IDLESCAN.
If an ALU2 error occurs while ALU2 is in other than IDLESCAN, equipment
check is set and "disconnect-in" is not presented to the channel.

155

3803 CHANNEL INTERFACE (continued)
Holley Monitor Trap
3803 Model 1/2

- Sync-F
A1 U2U07

N---P12

+ Gate--D

S05

p~
MST
Latch
Card

J1 0 -~-- B2V5D09
I
Channel A
I
PIN 8235422

Plug in any Unused
Socket 3803-2 A 1N2

L__

B2T5D09
Channel B

*Holley is prewired to
stop if J09 interface
pin goes active!

AIN2
Provide -6v to 8235422 Card
-6v
A3Q2B11 ~ B11
G11
M11
S11

Use Tri-Leads for Backpanel

Stop Holley Recording on Sync

157

3803 CHANNEL INTERFACE (continued)
Generally, the "disconnect-in" will not result in a 3803 OBR being logged. Consequently,
sense bytes 11 and 12 cannot be observed for the cause of the ALU error.
In order to determine the cause of the ALU errors not logged in an OBR, any of the following can be used dependent upon your particular situation.
1.

Enable the CE panel on the 3803 and activate *Stop on Control Check* switch.
This will cause the 3803 to hard stop on the ALU error and you can see the cause
in the CE panel lights. Set the ALU switch to ALU2 position first. If the customer
experiences a "disconnect-in" error and you do not get a stop on the CE panel, set
the switch to ALUI and you should stop on the next hit.
Note:

Be aware that using this method to locate the ALU error will cause the
customer to experience a job abort andlor system hang instead of a
probable recoverable error when the ALU error occurs.

Use MST CE indicator latch card PIN 5851882 (see Tools and Test Equipment
CEM 142) to monitor the individual ALU error bits. See 3803 Logic Pages AA461
and AB471.

When the 3803 brings up "disconnect-in", it also sets the bus-out check (byte 0,
bit 2) and ALU hardware error (byte 4, bit 10) indicators on. These two bits are
logged in the SDR counters as temporary errors.

We can therefore, temporarily - zap - the SDR software to assume that one of these two
error counters is ready to overflow. This forces an OBR and allows observation of sense
bytes 11 and 12. Either the "bus-out" or "ALU hardware" error can be used for the
- zap -, however, the ALU hardware error bit is probably the best as errors other than
ALU can cause bus-out checks. Shown on the next page are some examples (taken from
APAR Y05729) of how such a - zap - has been generated to log on OBR on every bus-out
error.

159

3803 CHANNEL INTERFACE (continued)

as R217 and VS2 R016
Name
VER
VER
REP
REP

IGE03001
30A
471 OF31 A, 91 03A008, 4770F320
398
0008000AOOOO
30E
47FOF39E
39E
9103A008, 4770F320, 9120A002,
4780F316,9601A008,47FOF320

VS1 R030
Name
VER
VE R
REP
REP

IGE03001
316
4710F326, 9103A008, 4770F326
3A4
0008000AOOOO
314
47FOF3AA
3AA
9103A008, 4770F32C, 9120A002
4780F322,9601A008,47FOF32C

This -Zap- should be removed once the problem has been resolved.

161

3803 DC VOLTAGES
3803 Power Supply
Power Supply Value
-4V (.::t,0.01V) See Note 1

+ 6V

(:t. 0.01 V)

See Note 1

Test Point

Ground

B2S2M11

B2S2D08

A2T4B06

A2T4D08

Note:
1. Maximum allowable ripple for - 4V is 80 MV peak-to-peak
and for + 6V it is 10 MV peak-to-peak.
CAUTION: Be sure to use a digital volt meter, PINs 453046, 453585, or equivalent
when making adjustments and exercise all standard safety practices.
VOLTAGE SIGNAL LEVELS
+ 12.0
+8.0
+12V

+0.7

o
-0.61
-0.96
MST -1

-1.57
-2.35

MST - 1 Card
Card (Contact Tab)
Voltage
B11 , G 11 , M 11 , and S11
+6
B06, G06, M06, and S06
-4
Ground
008, J08, P08, and U08
ALD pages showing voltage distribution:
TCU = YF - XXX
ZV - XXX (Board Distribution)
Models 3, 5, 7
Models 4, 6, 8
VB-XXX
YF-XXX

ZT-XXX

+6.0V
+4.0V

+6V

0.3V
O.lV

Gnd-- (Shorted, Open)
+OV
-O.lV

-4V

-0.3V
-3.0V

-4.0V
+4.4V

Inter-

+ 3.2V

face

Levels

+ 0.3V
+O.lV

163

ZT-XXX

3803 MOD 1 TO 2 - 6250 CONVERSION TIPS
The following are some hints for field conversion.
IMPORTANT:
• Follow the instructions in the conversion books very carefully.
• The majority of problems that occur after conversion result from cards or cables not
seated correctly and dirty, bent or recessed pins.

Conversion Kits

Recommended actions prior to installing conversion kit.
A.

General
1.

The EC Checklist (3803 ECA 070)
It is of the utmost importance that the EC checklist be correct. If it
isn't you will get the wrong parts. Do a physical check of each E/C
that is supposed to be installed.

The prerequisite E/Cs must be installed on the machine and the machine
tested prior to installing the conversion kit.

RPQ, features
; - If features and/or RPQs were ordered for the 3803-1,3420-3,5, 7
they must be installed and operational before doing the conversion.
- If features and/or RPQs were ordered for the 3803-2 configuration,
they must be installed after the conversion is complete and operational.
--

Recommend the use of a Circuit Test Probe Part 453587 expedite verification that the adds and deletes are correct.

Ensure that you are familiar with the conversion instructions before
starting. It is recommended that you read them at least once prior to
starting the conversion.

Review ITIPs (and data bank) to become aware of problems that may
be encountered during conversion.

165

3803 MOD 1 TO 2 - 6250 CONVERSION TIPS ( continued)
7.

Prior to installing logic cards and connectors make sure there are no
broken or bent pins. Inspect for recessed or loose pins on the data cable
connectors (channel-to-tape control unit and tape control unit to tape
unit).

All connectors and logic cards installed/replaced as called out in the conversion should be "popped" (eg, seated, removed and re-seated) a few
times to assure a good contact.

The installation of the auto cleaner does not eliminate the present head
cleaning procedure.

10.

II.

See "Stress Tape PIN 1848621" section,page 21 of this guide.

Only the logic board and logic cards in the conversion kit have been tested on a
"slave machine;" cables and jumpers have not.

Double check all card'plugging to ensure'that they reflect the converted status
of the machine. The original serial number of the TU should be plugged, not
the new model that it was converted to.

3803 Conversion Hints.
1.

If you have the 100 amp feature on the control unit, assure that the phases
are wired correctly before applying power.

The voltage jumpers between the B2 and B3 boards should be checked to
assure that they are not cross-wired before installing them.

When the channel interface adapter shoes are installed correctly you should
not see the silver plating.

The 3803-2 dc voltages are more critical than the 3803-1. Check with a
Digitec* voltmeter for:
+6V +0.010 Vdc
-4V +0.010 Vdc

The 3803-2 has a higher operating temperature than the 3803-1. Keep the
logic board covers closed for better air circulation.

*Trademark of United Systems Corporation

166

3803 MOD 1 TO 2 - 6250 CONVERSION TIPS ( continued)
6.

When installing the channel flat cables in the B2 board, hold them firmly
seated in the logic board while tightening the clamp.

167

3803 CONVERSION TIPS FROM DATA BANK
Model Conversion
Overrun errors, CRC checks when running from system. Okay offline.
**FIX**
Tie off had not been removed from data in line going to the interface.
Command status reject (EQ check) - converted Model 2 from Modell. Tie up resistor PIN
25220936 at 01A-A2Q2 missing or mis-wired. Should be A2Q2U07 to A2Q2U08 per conversion instructions.
Equipment check caused by a command status reject on a 3803 M/D002 converted from a
M/DOOl. Error occurs on any command that requires forward tape motion.
**FIX**
Tie up resistor P/N2520936 at 01 A-A2Q2 missing or miswired. Should be A2Q2U07 to
A2Q2U08 per conversion instructions, page 0400 step 45 and ALD Logic page AA411
Note 1.
Power-on reset B-bus parity errors ALUI microprogram check ALUI =7FF ALU2=7FF when
trying to go to drives microprogram check ALUI-301 B-bus parity ALU2=000. Problem
could be made solid by varying 4-volt supply to 4.03V.
**FIX**
Install as required ECA 039 EC733838
The EC is an as required for a Mod 1 but this ECA is not available for a Model 2 3803.
Therefore, if it is not installed prior to conversion, you may have this problem after conversion and the EC will be unavailable to you. See 3803 Tip 097 for further information on the
card part numbers involved and the interchangeability problems caused by these cards.
ECA 106 installs the new LSR cards on a 3803 Model 2.
Jumper assembly PIN 1766191 - there is an exposure that these jumpers may be wired incorrectly. To verify, refer to page 0140 in the 3803-1 to 3803-2 Conversion booklet. Item
"G" gives installation details. The cables should be wired as illustrated on page 0140.
Plated channel interface connectors PIN 5529194 and 5529199 have to be installed during
model conversion 1 to 2. In two cases we had intermittent microprogram detected errors
with the system test ST370. The PIN 5529199 had caused the error. One or more signal
connectors had wrongly contacted the plated area. The PIN 5529194 can have the same
kind of error because it is the same design.

169

3803 CONVERSION TIPS FROM DATA BANK (continued)
A read command gives solid P comp check after installation of basic conversion B/MI765720.
Offline read works okay.
**FIX**
Risk of error when using rework list 0400 of 3803 Conversion Instruction prior to
EC737151. On machines without EC733814 rework of net FC261GL2 on board 01A-B2
should be made as follows: .
Delete Probe Sid"e:
K5B03
G5B09
R2DI0
Add Nine Inches Long Wire:
From Pin
To Pin

CID13

GSB09

G5B09

R2DI0

SAGe burst is written in too high a density after model conversion. Inversed tape mark is
missing.
Sense on write from load point is:
1044000000403B000808000000875A ....
Read operation in 6250 mode and read/write operation in PE mode runs error free.
Microprogram detected error only on write in GCR mode.
**FIX**
Board Yl yellow wire cold flow shortage. Ground level on line BW231 GH6 name of signal
-6250 mode.
3803 M/D002 Conversion B/M1767973
B/M1767973 calls out a jumper PIN 0184603. This part number is incorrect; it should be
PIN 1847603.
Channel control checks channel timeout, CC3, various channel checks after conversion to
M/D002.
Scope interface signals during initial selection.
**FIX**
Short between uninsulated pins in the new plated interface connectors
PIN 5529194 and. 5529199.

170

3803 CONVERSION TIPS FROM DATA BANK (continued)
3803 Modell to Model 2 pre-conversion checklist PIN 902-106 page 2/5 checkpoint information.
The checklists have to be implemented by physically checking the machine, not by checking
machine histories.
Complementary checkpoint information is listed here under:
1.

EC 733838: Include the following checkpoint to ECA 39 as an "AND" condition.
Check resistor A2M2D08 to A2M2D13 and resistor B2E2M11 to B2E2P08.

EC 734821: Include the following checkpoint to ECA 42 as an "OR" condition:
Power-on reset card PIN 375382 at EC level 136587 or REA 24-24075

Delete EC 733834 ECA 42. It is picked up by EC 733843 ECA 46.

EC 734289B ECA 64. This prereq EC is needed only when the -4 volts reg asm PIN
2521578 has regulator board with slotted holes for mounting capacitors C1, C2, and
C4.

B2M2 PIN incorrect per EC 734874 checklist for conversion to 6250 bpi. Current plug chart
in 3803 Volume 1 may reflect B2M2 to be PIN 8218309 at EC 733816, and PIN 8218365
at EC 733814. Your machine may contain PIN 8218307. B2M2 is PIN 8218307 at EC
733816A (ECA 015), and PIN 8218309 at EC 733816 (ECA 018).
Installation of EC 734873, which is prerequisite for 3803 Modell to Model 2 conversion
may cause D-bus parity checks or microprogram hangup during power-on reset. This problem is corrected by EC 733838 ECA 039 which must be installed concurrently with EC
734873.
AAA - 3803 Modell to Model 2 conversion errors in rework instruction:

Page 0400 (XE200) salmon color at EC 734116 and REA 24-26625/24-26629. The
deleted net FC261 GL2 between K5B03 and G5-B09 is not a printed circuit. It is a
yellow wire - this error will be corrected at EC 734877

Page 410 - board 01AB2 rework - net FC021GA4. Add must be read Q3D06 to
P3D06 - Ensure this add is made.

171

3803 .CONVERSION TIPS FROM DATA BANK (continued)
Cabling Requirements
The increased data rates of 6250 bpi call for shorter signal cables from the channel to the
3803-2. Intervening control units shorten the cables even more. For each intervening
control unit, subtract 20 feet when Model 8 tape units are attached, and subtract 5 feet
when Model 6 tape units are attached. When a 2914 channel switch is used to modify
channel access to a 3803-2, subtract 40 feet. Measurements are based on a 3803-2 on the
specified channel with at least one 3420 of the specified model attached.
Verify that the existing bus and tag cables are the proper lengths. If the cables you have
exceed the allowable lengths, or do not match in length, order new cables. Cables of
different lengths can cause timing differences.
The total cable length from a 3803 to any 3420 must not exceed 120 feet (tape unit to
tape control plus the communicator cable). The maximum cable length from the tape
control to the channel is 200 feet when 3420 Models 3,5, and 7 are attached to a 3803
Model 2.

2860

2880

2860

2880

2860

2880

System

3420-8

3420-6

3420-4

370-195

119

200

370-168

119

200

370-165-2

119

200

'370-165

119

200

360-195

119

200

360-91

200

200
119

200

360-85

360-75

200

360-67/65*

200

3420-8

3420-6

3420-4

370-158

103

200

370-155-2

103

200

370-155

103

200

370-145*

119

200

370-135*

200

360-50*

200

172

200

3803 PREVENTIVE MAINTENANCE SCHEDULE
3803 Control Unit
Code
U R

Location
Operation

Frequency

Action

Air Filter

2 months

Check cooling air
fIlter for restriction
of air flow. Clean
or replace as required.

dc voltage

6 months

Check dc voltages.
Adjust as required to
the levels specified on
decals.

173

3803 SALES FEATURE CODES
Applies To:
M M M

coc:
0

'flc:
::J

u..

>
0

cc:

coc:

0
'+:i
(.)

::J

u..

cc:

Note:

Feature
Code

Description

3551
6148
6408
8100
9570
See Chart A
9041
9042
9043
9045
9046
9903
9905
5310
6320 (See Note)
7850
9181
9182
9183
9001

Dual Density
Remote Switch Attachment
Seven Track
Two Channel Switch
Single Density
Tape Switching
Red Covers
Yellow Covers
Blue Covers
Gray Covers
Wh ite Covers
208 V AC Power
230 V AC Power
9-TRK NRZI (6250 + 1600 + 800)
7-TRK NRZI (800 + 556 +200)
2860 Channel Attachment
First 2860 Channel
Second 2860 Channel
Third 2860 Channel
Required if More Than 6 Mod 8s

Feature Code 5310 must be
installed prior to installing
Feature Code 6320,

175

d
e
I
1
X
X

d
e
I
2

X
X
X
X

d A
e L
L
I
3
X

X
X

X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X

3803 SALES FEATURE CODES (continued)
Chart A - Tape Switching Feature

Switch
Options

2x8

3x8

4x8

2 x 16

3x 16

4 x 16

Features Required

Feature Numbers
On 1st On 2nd On 3rd On 4th
3803
3803
3803
3803

Communicator 1-2 9071

9071

2 Control Switch

Communicator 1-2 9071

9071

3 Control Switch

Communicator 1-2 9071

9071

4 Control Switch

Communicator 1-2 9071

9071

2 Control Switch

1792

Communicator 1-2 9071

9071

1792

1793

1794

Communicator 3-4

9073

3 Control Switch

1793

Communicator 1-2 9071

9071

Communicator 3-4

9073

4 Control Switch

1794

176

3803-1 FEATURE IDENTIFIER
Identifica tion
9-Track NRZI..

. Check for a card in location AI-N2 with Al board PIN
2521390
7-Track NRZI. . . . . Al board will have PIN 2521386
2-Channel Switch (MIS) . Check for 8-channel I/O connectors
Communicator 1 .
. Check for only two light gray I/O connectors on the left
side of I/O tailgate
Communicator 2 . .
Check for four light gray I/O connectors on the left side of
I/O tailgate
1x 8
. . Nothing will he on left side of I/O tailgate
. . . . . . . Check for two light and two dark I/O connectors on the
2x8
left side of I/O tailgate
3x8
. . . Check for two light and four dark I/O connectors on the
left side of I/O tailgate
. . . . . . . Check for two light and six dark I/O connectors on the
4x8
left side of I/O tailgate
Note:

Only RPQ machines may have both the 9-track NRZI and the 7-track NRZI
feature.

I/O Tailgate

Commun

lx8

2x8

Channel
I/O

Connectors

177

3x6

4x8

3803-1 FEATURE IDENTIFIER (con tinu edj
38038 with RPQ8
Machines with RPQs installed have special "version" pages for logics impacted by the
RPQ. The following list shows this version number (which is found in the lower right
corner of those pages affected), along with a cross-reference t<;> its applicable RPQ
number.
Version
Number
007
054
069
079
101
A17
A19
Bll
209
A27
A37
409
100
837 and
179

RPO
Number

Title
7 Track Basic
Remote Channel Switch
Force NRZI Write
7 & 9 Track Compatibility
Character Insert (single
or dual density)
Character Insert
(7 trk machine)
Character Insert (with
9 trk 200 machine)
Character Insert (with
7 and 9 trk)
9 trk-200 BPI Read/Write
7 trk-200 BPI Read/Write
7 trk-200 on 7 and 9 trk
Set Density
Read Special Tape Mark
Sage Mode on 7 and 9 trk
with 7 trk 200

178

None
870054
EB7207
870046
870053
870053
870053
870053
870043
870045
870057
WD1834
S10079
EB7322

3803-1 FEATURE INSTALLATION TIMES
COM1 =Communicator 1
COM2=Communicator 2
PE=Phase Encode
7TK=Seven-Track
2X8=2 Control Switch
3X8=3 Control Switch
4X8=4 Control Switch

FC=Feature Code
MIS=2-Channel Switch
DD=Dual Density (PE and 9TK NRZI)
SL=Selection Logic (lX8)

3803 Modell Feature Times
FC

B/M Number

Title

Mach

B/M2517155
B/M2517163
IB/M2520827
B/M2520832
B/M2520833
B/M2520834

Install Remote Chan Sw
Remov~ Remote Channel Sw
DD W/MIS to DD W/O MIS
Convert 1X8 to 2X8 W/COM1
Convert 1X8 to 3X8 W/COM1
Convert 1X8 to 4X8 W/COM1

03.9
03.9
03.0
06.0
07.8
07.9

0.1
0.1
0.6
0.9
0.9
0.9

B/M2520836
B/M2520837
B/M2520838
B/M2520839
B/M2520840

7TK W/0 MIS to 9TK W/MIS
7TK W/O MIS to 9TK W/MIS
9TK W/O MIS to 7TK W/MIS
DD W/O MIS to PE W/MIS
PE W/O MIS to 7TK W/MIS

05.7
05.7
05.7
04.2
05.7

0.6
0.6
0.6
0.6
0.6

8100

B/M2520848
B/M2520849
B/M2520851
B/M2520852
B/M2520853
B/M2520854

PE W/O MIS to PE W/MIS
PE W/MIS to PE W/O MIS
PE W/O MIS to DD W/MIS
PE W/O MIS to DD W/O MIS
PE W/MIS to DD W/MIS
PE W/MIS to DD W/O MIS

04.1
03.0
04.2
01.7
01.7
04.2

0.9
0.6
0.6
0.6
0.6
0.6

6408

B/M2520860
B/M2521340
B/M2521341

PE W/O MIS to 7TK W/O MIS
PE W/MIS to 7TK W/MIS
PE W/MIS to 7TK W/O MIS

03.8
03.8
05.7

0.6
0.6
0.9

B/M2521345

DP W/O MIS to DD W/MIS

04.1

0.9

B/M2521350
B/M2521351
B/M2521352

COM2 to 2X8 with COM1
COM2 to lX8 with COM1
COM2 to 4X8 with COM1

10.0
09.0
11.4

0.9
0.9
0.9

6148
6148
8100
1792
1793
1794

9073

179

3803-1 FEATURE INSTALLATION TIMES (continued)
FC

BLM Number

9073
9071
9073

B/M2521353
B/M2521354
B/M2521355
B/M2521356
B/M2521357
B/M252135B
B/M2521359
B/M2521360
B/M2521361
B/M2521362
B/M2521363
B/M2521364
B/M2521365
B/M2521366
B/M2521367
B/M252136B
B/M2521369
B/M2521370
B/M2521371
B/M2521372
B/M2521373
B/M2521374
B/M2521375
B/M2521376
B/M2521377
B/M2521378
B/M2521379
B/M2521639
B/M2521640
B/M2521641
B/M2521642
B/M2521630
B/M2521631
B/M2521632
B/M2521633
B/M2521634
B/M252I635
B/M2521636
B/M2521637
B/M2521638

1793
1794
9071
1792
1794
9071
1792
1793
9073
9073
9073
9073
1792
1793
1794
9071
9071
9071
1794
9570
9570
9570
3551
BI00
8100

640B
6408
640B
9570
9570
9570
3551
2551

Title
Convert COM2 to SL (lXB)
Convert 1XB to COM 1
Convert 1XB to COM2
Convert 2XB with COM 1 to 1XB
Convert 2XB to 3XB
Convert 2XB to 4XB
3XB W/COM to 1XB W/O COMI
Convert 3XB to 2XB
Convert 3XB to 4XB
Convert 4XB W/COMI to lXB
Convert 4XB to 2XB
Convert 4XB to 3XB
Remove 2XB W/COMl, add COM2
Remove 3X8, Install COM2
Remove 4XB, Install COM2
Convert COMI to SL (lXB)
Convert COMI to COM2
Convert COM 1 to 2XB
Convert COMI to 3XB W/COMI
Convert COMI to 4XB W/COMI
Convert COM2 to COMI
Remove 2XB, Install COM 1
Remove 3XB, Install COMI
Remove 4 XB, Install COM 1
DD W/O MIS to PE W/O MIS
DD W/MIS to PE W/MIS
9TK NRZI W/MIS to PE W/0 MIS
7TK W/MIS to 9TK W/O MIS
7TK W/O MIS to 7TK W/MIS
7TK W/MIS to 7TK W/O MIS
Logic for 7TK to 9TK
NRZI W/O MIS to 7TK,W/0 MIS
DD W/MIS to 7TK W/MIS
DD W/MIS to 7TK W/O MIS
Logic for 9TK to 7TK
7TK W/O MIS to PE W/O MIS
7TK W/MIS to PE W/MIS
7TK W/MIS to PE W/O MIS
7TK W/O MIS to DD W/O MIS
7TK W/MIS to DD W/MIS

180

Mach

Sys

05.6
03.6
03.6
04.0
OB.5
09.0
05.4
05.0
05.3
05.7
05.5
02.1
03.5
03.6
03.7
05.6
02.6
OB.5
09.0
11.4
02.B
03.5
03.5
03.7
01.7
01.7
04.2
05.7
04.1
03.0

0.4
0.4
0.4
0.9
1.5
1.5
0.7
1.3
0.9
0.7
1.3
0.9
0.9
0.9
0.9
0.4
0.4
0.9
0.9
0.9
0.2
0.9
0.9
0.9
0.6
0.6
0.6
0.6
0.9
0.6

03.2
03.B
05.7

0.6
0.6
0.6

03.8
03.2
05.7
03.2
03.B

0.6
0.6
0.6
0.6
0.6

3803-1 FEATURE INSTALLATION TIMES (continued)
3803 Modell Feature Times W/OEC733814
FC

B/M Number

3551
6408

B/M2524289
B/M2524290
B/M2524291
B/M2524292
B/M2524293
B/M2524294
B/M2524295
B/M2524296
B/M2524280
B/M2524281
B/M2524282
B/M2524283
B/M2524284
B/M2524285
B/M2524286
B/M2524287
B/M2524288
B/M2524297
B/M2524611

9570
6408
9570
3551
8100
8100
8100
8100
8100

8100
8100

Title
PE W/MIS to DD W/O MIST
PE W/MIS to 7TK W/O MIS
DD W/O MIS to DD W/MIS
9TK NRZI W/MIS to PE W/0 MIS
DD W/MIS to 7TK W/O MIS
7TK W/MIS to PE W/O MIS
7TK W/MIS to 9 NRZI W/O MIS
7TK W/O MIS to 7TK W/MIS
DD W/MIS to DD W/O MIS
7TK W/O MIS to 9TK W/MIS
7TK W/O MIS to 9TKPE W/MIS
9TK NRZI W/O MIS to 7TK W/MIS
DD W/O MIS to PE W/MIS
9TK PE W/0 MIS to 7TK W/MIS
9TKPE W/O MIS to 9 PE W/MIS
PE W/MIS to PE W/O MIS
PE W/O MIS to DD W/MIS
7TK W/MIS to 7TK W/O MIS
Voltage Conversion

181

Mach

Sys

04.2
05.7
04.1
04.2
05.7
05.7
05.7
04.1
03.0
05.7
05.7
05.7
04.2
05.7
04.1
03.0
04.2
03.0
02.5

0.6
0.9
0.9
0.6
0.6
0.6
0.6
0.9
0.6
0.6
0.6
0.6
0.6
0.6
0.9
0.6
0.6
0.6
0.0

3803.;2 FEATURE INSTALLATION TIMES
COM1 =Communicator 1
FC=Feature Code
MIS=2-Channel Switch
COM2=Communicator 2
DD=Dual Density (PE and 9TK NRZI)
PE=Phase Encode
SL=Selection Logic (lX8)
7TJ<=Seven-Track
9TK=Nine-Track NRZI
2X8=2 Control Switch
3X8=3 Control Switch
4X8=4 Control Switch
Aux Gate=Gate on the side of 3803 field converted from a Modell to a Model 2. It is
one board in size.

3803 Model 2 Features
FC

8100
5310

6320
9071
9073
1792
1793
1793
1794
1794
1792
1793

Mach

02.0

0.5

AC Voltage Conversion
DC'Voltage Conversion
Install MIS W/EC733814
Remove MIS W/EC733814
Install 9TK NRZI

02.0
02.5
03.9
04.1
03.0
00.7

0.5
0.2
0.2
0.9
0.6
0.5

B/M1846297
B/M1846298
B/M1846300
B/M1846301
B/M1846302
B/M1846303
B/M1846304

Remove 9TK NRZI
Add 7TK to 9TK NRZI
Remove 7TK NRZI
Convert SL (1 X8) to COM 1
Convert SL (1 X8) to COM2
Convert SL to 2X8 with COM 1
Convert SL to 3X8 with COM1

00.7
00.7
00.7
03.6
03.6
06.0
08.0

0.5
0.5
0.5
0.4
0.4
0.9
0.9

B/M1846306
B/M1846307
B/M1846309
B/M184631I
B/M1846312
B/M1846313

Same as above, for Aux Gate
Convert 1X8 to 4X8 with COMI
Same as above, for Aux Gate
Convert COMI to (lX8)
Convert COM1 to!2X8 with COM1
Convert COM1 to 3X8 with COMI

07.3
09.4
07.9
05.6
08.5
11.4

0.9
0.9
0.9
0.4
0.9
0.9

B/M Number

Title

B/M1766197
B/M1766249
B/M1766250
B/M1766257
B/M1766259
B/M1766253
B/M1766254
B/M1766258
B/M2524611
B/M1766248
B/M1767978
B/M1767979
B/M1846295

Install 100 Amp Service

Remove 100 Amp Service

183

3803-2 FEATURE INSTALLATION TIMES (continued)
Mach

Sys

Same as above, with Aux Gate
Convert COM1 to 4X8 with COM1

09.9
12.9

0.9
0.9

B/M1846318
B/M1846320
B/M1846321
B/M1846322
B/M1846323
B/M1846325
B/M1846326

Same as above, with Aux Gate
Remove MIS W/O EC733814
Convert COM2 to SL (1 X8)
Convert COM2 to 2X8 with COM1
Convert COM2 to 3X8 with COM 1
Same as above, with Aux Gate
Convert COM2 to 4X8 with COM1

11.4
03.0
05.6
10.0
11.4
09.9
13.4

0.9
0.6
0.5
0.9
0.9
0.9
0.9

B/M1846328
B/M1846329
B/M1846330
B/M1846331
B/M1846332
B/M1846333
B/M1846334
B/M1846335
B/M1846336
B/M1846337
B/M1846338
B/M1846339
B/M1846340
B/M1846341
B/M1846342
B/M1846343
B/M1846344
B/M1846345
B/M1846346
B/M1846347
B/M1846348
B/M1848592
B/M1848603

Same as above, with Aux Gate
Remove 2X8, Install COM 1
2X8 to a 1X8, Remove COM1
Remove 2X8, COM1, Add COM2
Convert 2X8 to 3X8
Convert COM2 to COM1
Same as 1846332 but Aux Gate
Convert 2X8 to 4X8
Convert COM1 to COM2
Same as B/M1846335 but Aux Gate
Remove 3X8, Install COM1
3X8 to 1X8, Remove COM1
Remove 3X8 with COM1, Install COM2
Convert 3X8 to 2X8
Convert 3X8 to 4X8
Remove 4X8 + COM1, Add COM1
Convert 4X8 + COM1 to 1X8
Remove 4X8, Install COM2
Convert 4X8 to 2X8
Convert 4X8 to 3X8
Install MIS W/O EC733814
Remove Remote Channel Switch
Install Remote Channel Switch

11.4
03.5
04.0
03.5
10.0
02.8
08.5
10.5
02.6
09.0
03.6
05.4
03.6
05.0
05.3
03.7
05.7
03.7
05.5
02.1
04.1
03.9
03.9

0.9
0.9
0.9
0.9
1.5
0.2
1.5
1.5
0.4
1.5
0.9
0.9
0.9
1.3
0.9
0.9
0.7
0.9
1.3
0.9
0.9
0.1
0.1

B/M Number

1793
1794

B/M18463l5
B/M1846316

1794

1791
1793
1793
1794
1794
9071
9073
1793
9071
1}93
1794
9073
1794
9071

1792
1794
9071
9073
1792
1793
6148

Title

184

3803 ECA CHECKLIST
ECA

E/A

Description

Checkpoint

001

733766V

Release to manufacturing

None

002

733801

Basic sys paper cleanup and
24 wire panel rework C-test
exit

Check for wire or land from
01A-A2CSD12 to
01A-A2CSD10

003

733820

Pathfinder manual update

Check EC level or pathfinder.

004

733821

Mechanical (cable retention) Check for four U-c1amps holdprovide. a more positive
ing coaxial interface cables
clamping system for replugged into 01A-B2 board.
tention of coaxial I/O cables
with EC 733763 (E008)

OOS

733809

Paper only to reflect 7track

Check EC 733809 on logic
page QB101.

006

733700

Power on/off sequence
decal

Check for mainline switch
decal at EC 734700.

007

733810

Sys logic update (REAs
24-22893, 24-22906,
24-22907,908,909, 911,
and 24-22919

Check for wire 01 A-A2T2D09
to 01A-A2USD13.

008

733763C

Mechanical brackets (mach
prior to 11000)

Check for U-shape bracket
cover, above and below B2
board where the interface
cables are plugged.

009

733806C

Supply one page of micro
programming.

Check existence of microcode
page 60A of PIN 2S21 022.

010

733819

Provides parts to change
rear machine cover roller
from brass to rubber and
includes slider springs to
prevent ESD interference

Check for brass slider springs·
on rear machine cover.

011

733826

MST-A Alt path switching
hangup

Check 01A-B2H2 at EC
733816. Refer to card location list for card EC level.

012

733827

Correct check character
spacing on NRZI write
tape mark. (Both 7 and
9-track NRZI)

Check 01A-A2H2. Refer to
card location list for card EC
level.

185

3803 ECA CHECKLIST (continued)
ECA

E/A

Description

Checkpoint

013

733823

Mechanical and ESD

Check for ground wire on
left side cover (facing wiring
side of machine) closest to
interface cables from hinge
'bracket to cover.

014

733804

Replace crosspoint switch
cards with ones having a
more stringent card test,
but of the same part
number.

None

015

733816A

Board wiring (REAs
24-22946, 22937, 22984).
Prior to SN 11000.

Check for wire on 01A2 board
from H5D11 to H3D05.

016

733815

7-track C-test exit. Logic
only.

Check EC level of logic page
RD171.

017

733147

-RPQ machines onlySupply logic pages to
machines W/0 RPQ
870054.

Check EC level of logic page
AA003.

018

733816

REAs for emulator, 145
attach, disable ripple at
bus in times for CE operation while the interface
was enabled, overrun.

Check for wire on 01A1
board from H3B10 to L2B05.

019

733141

-RPQ machines onlySupply logic to machines
W/O RPQ 870053.

Check for this EC on logic
page AA001, AA002, and
AA003.

020

733804A

New plug list for A3 and
B3 boards.

Check for this EC on plug
list AA009.

021

733143

Supply logic pages AAOO 1
and AA003 to machines
WIO RPQ 870045.

Check for this EC on logic
page AAOOI and AA033.
(See ECA notice.)

022

733824

7-track C-test exit. Logic
only.

Check EC level of logic page
RD211.

023

733830

Pathfinder manual update.

Check pathfinder EC level.

186

3803 ECA CHECKLIST ( continued)
ECA

E/A

Description

Checkpoint

024

733814

New B2 board to meet 370
requirements.

Check 01A-B2 panel for +6V
gold rail connecting B11 pins:
with 733814 - B2N2B11 to
M2B11 W/O 733814 B2N2B11 to L2B11.

025

733146

- RPQ machines only Provide logic pages for
machines with RPQ
870043.

Check EC level of logic page
PR161 PIN 2516824.

026

733835

Correct system hang
condition for lost device
end associated with load
check interrupt and
anticipated mounts.
(Prerequisite to E046.)

Check 01 A-A2Q2. Refer to
card location list for card EC
level.

027

733828

Increase PE skew handling capability. (REA
24-24002). (prerequisite to E046)

Check 01A-A1H2. Refer to
card location list for card EC
level.

028

733829

Correct problem when
a one-bit splash occurs
in the IBG. (picked up
by E031 and E040.)

Check 01A-A1C2. Refer to
card location list for card EC
level.

029

734235

Improve -4V regulator
Check for resistors R9 and
board (picked up by E035). RIO on -4V regulator board

A2.
030

733831

Basic system - 7 and 9track NRZI read (REA
24-24012). Correct
noise detection on tracks
3,4, and 6 for NRZI
read W/EC 733816.

Check 01 A-AI L2. Refer to
card location list for card EC
level.

031

733833

Envelope checks with
switching speed or
detection from Mod 5 to
3 or 7. W/733810 incorporates E028. (Picked up
by E040.)

Check 01A-A1C2. Refer to
card location list for card EC
level.

187

3803 ECA CHECKLIST ( continued)
ECA

E/A

Description

Checkpoint

032

733834

Prevent ALU2 hang in
velocity routine when
crease is encountered in
preamble of PE data;
Gate line 'block' with
move tag (REAs 24-24013,
19, 22, and 24-24023).
(prerequisite to ECA
046.)

Check for wire from
A2E4D13 to A2U1D13.

033

733148

Replaces 7 -track and 9track RPQ cards on
machines at 733145 level.
RPQ 870046.

Check 01A-A1M2. Refer to
card location list for card EC
level.

034

733817

- Paper only - Supply
logic to allow plugging
, or equivalent imbedded
cards.

035

734247

Power supply logic only
(composite with E029).

Check for EC 734247 on
power supply logic page
YF031.

036

733841

Tie down unused net to
prevent noise from causing ROS errors. (REA
24-24058)

Check for tiedown resistor
PIN 2520942 (yellow) from
A2H2S10 to A2H2506.

037

733840

Pathfinder update

Check EC level of pathfinder.

038

734287

Torque screws on
capacitors in the power
supply.

Assure -4V power supply
mounting capacitor screws
are tightened.

039

733838

Allow plugging of cost
reduced ALU cards. (RE
(REAs 24-24051 and 2424054)

Check for resistor from
A2M2D08 to A2M2D13, and
B2E2M11 to B2E2P08.

040

733839

Decrease excessive write
errors caused by temperature sensitive cards.
Obsolete PIN 8218373
and 8218374. (REAs
24-24081 and 24082)
(composites ECA 028 and
031).

Check 01A-A1C2. Refer to
card location list for card EC
level.

188

Check EC level or logic.

3803 ECA CHECKLIST (continued)
ECA

E/A

Description

Checkpoint

041

734299

Paper only - power supply.

Check logic page YF030 for
this EC.

042

734281

Correct random power-on
resets. Reduce ESD exposure by a capacitor change
+6 volt regulator SMS card.

Check for EC 734281 label
on top of DC box or check
power-on reset card PIN
375382 for EC 136587 or
REA 24-24075.

043

733837

Clock card tie-ups prevent
Check 01A-A2K2. Refer to
noise from stopping ALU
card location list for card EC
with EC 733816. Pick up
level
usage of card PIN 8218344.
(Picked up by E069).

044

733842

Reset RDD by -2 time so
as not to set lost byte latch
with 7-track W/EC 733824.
Also corrects several other
problems. (See EC listing.)

Check for yellow wire from:
01A-A1Q2Bll to
01A-A1 Q2D07.

045

733152

- RPQ machines only Corrects LRC spacing 200
bpi RPQ 870045.

Check 01 A-AI J2. Refer to
card location list for card EC
level.

046

733843

047

733844

Lost record due to creased
tape. (ECAs 026, 027, and
032 are prerequisites)
Improve interface ground
integrity. (ESD) (REAs
24-24070 electrical REA
24-24077) mechanical add
foam in cable raceways.

Check 01A-A2Q2. Refer to
card location list for card EC
level
Check for wire from 01AB2U5B07 to 01A-B2V5B07.
Raw board EC levels of
732387 and 732391 do not
have wire. All machines
should have foam in raceway.

048

733847

Allow device partitioning
without stopping data processing (tie up the clock
out line device interface).
REA 24-24084 (picked up
by E050).

Check for tie-up resistor from
01A-B2Q2D08 to 01AB2Q2B04.

'049

733154

- RPQ 870053 - Correct
lost byte checks on character insert.

Check 01 A-AI S2. Refer to
card location list for card EC
level.

189

3803 ECA CHECKLIST ( continued)
ECA

EfA

Description

Checkpoint

050

733848

Allow enabling of PE ID
burst checking. Provide
availability to check PE
ID burst at the CE's
option.

Check for yellow wire from
01A-A1L5Dll to 01AA1G3B07.

051

733155

- RPQ 870046 -7-track
and 9-track 200 bpi paper
only.

Check for yellow wire from
01 A-AI N2D09 to 01AA1P3D12.

052

733852

Change write timing on
LSR store operation.
Correct E039. (Picked
up by E069.)

Check 01A-A2K2. Refer to
card location list for card EC
level.

053

---

World Trade Only
(Same as domestic ECA
040.)

------------

054

734466

Released the tools for the
installation of the 3420
new reel latch.

Check for the reel latch tools
called out in 3420 ECA E033.

055

734501

Installs a plastic insulator on top of the fan
guards in the power
supply.

Check for this insulator.

056

734753

Released new tape unit
cleaning procedure and
updated operator's
guide.

Ensure the use of the 3420
cleaning procedure - SY325033-0.

057

733853

Correct NRZI write lost
byte when an oxide void
occurs on tape during a
write.

Check 01A-AIP2. Refer to
card location list for card EC
level.

058

733854

Update to switch chart
and reference pages.

Check EC level of logic page
XC701.

059

733853A

Correct logic pages released on E057. (Picked up by E063)

Check logic page XN141 for
EC 733853A.

060

734503

Circuit protector change
from lOA to 15A for
CP17.

Check CP17 for 15 amp
breaker in top of ac box.

190

3803 ECA CHECKLIST (continued)
ECA

E/A

Description

Checkpoint

061

733850

Pathfinder Manual
update.

Check Pathnnder EC level.

062

733856

Excessive read VRC
errors (NRZI Op) REAs
24-24092 (0 Tk) 2424093 (imbedded card),
24-24094. (7-track). 2424095 (RPQ card).

Check 01A-AIQ2. Refer to
card location list for card EC
level.

063

734867

LWR-NRZI diagnostic 'K'
fails with read VRC errors
(correct 733853) REAs
24-24100 and 24-24101.
Mandatory with E057
(composites E057 and
EOS9).

Check 01A-A1P2. Refer to
card location list for card Ee
level.

064

734289B

Check for a zinc coated copper clip in the slotted holes
for the mounting of capacitors in the -4V power supply. Round mounting holes
do not need EC.

065

734869

Improve the electrical and
mechanical connection of
the ft1ter capacitors of the
-4V reg board. Mandatory on machines W/O EC
734512.
Clock card-ESD. (Clock
ESD) (REA 24-24102)
(Picked up by E069).

066

734866

Correct improper handling
of creases (or contamination which appears as a
crease) during some tape
operations. Corrects
733843.

Check 01 A-A 1H2. Refer to
card location list for card EC
level.

067

733174

Correct intermittent Ccompare errors on 3803-1
with RPQ 870046.

Check 01 A-A1 H2. Refer to
card location list for card EC
level.

068

734872

Rewire 01A-B2 board to
meet interface specs on
machines with EC 733814.

Check for yellow wire from
01A-B2V2D09 to 01AB2U2D09.

191

Check 01A-B2F2. Refer to
card location list for card EC
level.

3803 ECA CHECKLIST ( continued)
ECA

E/A

Description

Checkpoint

069

734873

Extend sample of incremented IC address during
long ALU cycles to eliminate wrong branches.
(Composites E043 , E052,
and E065)

Check 0IA-A2K2. Refer to
card location list for card EC
level.

070

733874

E/A

EC identifier list essential
only for machines requiring the 6250 bpi feature.

None

071

735961A

Update logics to include
replaceable parts in order
that power supply asms
can be removed from the
part~ catalog.

Check for EC 735961 or higher on logic page YF036.

072

733198

Eliminate compatibility
problems between RPQ
ME0704 and basic 3803-1
machine features.

Check for card PIN 8218281
in location A-AI B4 and wire
from A-AIL3B03 to
A-AIB4B07.

073

905986

World Trade Only

------------

074

734098

Established level of box
for 'C' exit.

3803-2 - Check logic for EC
734098 or higher.

075

734112

Meet 'C' test exit objectives.

Check MLM for 3803-2 page
90-120 for EC 734112 or
higher.

076

734111

Reduce E8D, I/O channel connector block.

Look for plated connectors
for channel interface shoes.

077

734120

Reduce flat cable damage
during shipment.

Check for screws in the back
of the channel I/O shoes to
hold the adaptors in place.

078

734099A

World Trade Only

------------

079

3803-2
734879
3803-1
734878

Correct 237 abends due
to unexpected interrupt
with zero status and
other conditions.

Check for PIN 8232753 in
0IA-A2T2.

Release RPQ 810112
velocity retry extension.

3803-1 and 3803-2 check
for PIN 8232752 in
0IA-A2G2.

080

734875

A
A

192

3803 ECA CHECKLIST (continued)
ECA

E/A

Description

081

736697

Eliminate false errors when 3803-2 - Check for card PIN
a write tape mark command 8237119 in 0IA-A2H2.
is issued.

082

736699

Correct tape runaway condition.

083

734877A
734877B

E
E

Logic update not picked up 3803-2 - Check logic page
FC261 for EC 734877 A or
on parent E/C 734877.
higher level. (It should be a
white page.)

084

734882

Pathfinder manual update.

3803-1 and 3420 - Check
Pathfinder for addendum
PIN 2517072 at EC 734882.

085

736693

Improve -4V regulation
on the power supply.

3803-2 - On 3803-2 lX8,
check for .16 Ohm resistor
R8 PIN 2521454 on regulator board A2.

086

736698

MLMupdate.

3803-2 and 3420 - Check
MLM for EC 736698 or higher on page 00-005.

087

736934

Improve -4V regulation.

3803-1 - Jumpers added from
heatsink to -4V caps (-)
side to Cl, C2.

088

736678C

Improve electrical connection from the secondary of the ferro transformer to the -4V regulator board assemblies

3803-1 - Check for round
cables from Al and A2 -4V
regulator boards to the ferro
transformer.

Checkpoint

3803-2 - Check for continuity between X-Yl T2B07 ,
X-Yl T3011 and X-Yl T5B02.

089

737145
736701

Correct subsystem failures
3803-2 - Check for card PIN
(digital information re8237126 in location X-YI02.
ceived from tape unit
during read track detection).
PE clip level controls are
changed.

090

---

World Trade Only

091

---

World Trade Only

193

-----------------------

3803 ECA CHECKLIST (continued)
ECA

E/A

Description

Checkpoint

092

735164

MLM update.

3803-2 and 3420 - Check
MLM page 00-005 for EC
735144 or higher EC.

093

735170

Pathfinder update to reduce maintenance on capstan tachometer.

3803-1 - Check Pathfinder
page 6-160 for EC 735170
or higher EC level.

094

736939

E/A

3803-1 as required,
3803-2 essential- Change
value of frequency compensating capacitor on +6V
and -4V SMS regulator
cards. Eliminate lkHz/120
MV of ripple onset at high
temperature.

3803-1 and 2 - Check the -4
and +6V regulator card for
EC 736939.

095

736940

Provide an improved
bracket for the mounting
of 20A circuit breaker.

Remove cover to access rear
of 20 amp CB located below
the power sequence switches.
Check for a one piece bracket
that encompasses the 20 amp
CB.

096

443802

MLM udpate.

Check page 00-010 for EC
443802.

097

906517

World Trade Only

098

---

World Trade Only

099

443885

Cancelled

----------------------------------

100

443901

Provides plated connectors
in 01 T gate for drive cable
attachment to minimize
ESD problems.

Check for plated connectors
in 01 T gate (drive connectors).

101

443902

Adds plated I/O channel
connector block between
the internal coax connector and the external
channel cable.

Check for plated connector
(open 3803 side cover to'
check).

102

733226

Prevents erroneous correction of track 0 when
a tie byte of 03 is indicated.

Check for card PIN 8237131
at location Yl D2.

194

3803 ECA CHECKLIST ( continued)
ECA

E/A

Description

Checkpoint

103

443805

MLM update to reflect
changes made as a result
ofECA086.

Check MLM 08-350 for EC
443805.

104

443803

Replace entire Pathfinder.

Check Pathfinder for EC
443803.

105

449058

Safety change provides
visual verification of the
installation of four jumpers provided by ECA
087.

None

106

449048

Eliminates "B"-bus parity
errors, IFCCs, ALU1 and
ALU2 hangs, and clock
card failure indications.

Check for resistors (PIN
2520936) (blue):
A-A2M2D13 to A-A2M2D08
A-B2E2M11 to A-B2E2P08

107

448502

Established factory first
customer ship level for
3803 Model 3. The Model
3 attaches to the 31151
3125 MTA only.

None

108

448503

Provides MSTA (ROS 1)
cards to update 3803-3
microcode.

Check for card PIN 8252044
in location 01 A-B2H2.

109

---

World Trade Only

------------

110

443804

Update 3803-2 MLM to
EC 443804 level.

Check MLM page PLAN 6
for EC 443804.

111

449064

Decreases possibility of
temporary read errors in
6250 mode when the
capstan is not kept properly cleaned.
This is an (8) eight-word
patch.

Check for microcode patch
card (PIN 8215414) in location 01A-A2G2. If none, EC
is not installed. If card exists
see MLM 80-030. If ~ is
plugged "7 BB" and ® is
plugged "67BD" then EC is
installed.

195

3803 ECA CHECKLIST (continued)
ECA

E/A

112

448505

Prevents system from
locking up when reporting an uncorrectable
,data error on a channel
control check during
paging or a halt.

113

845987

Logic update; replace logic YF037 at PIN 2521590 for
page YF037 at EC 449058 a Mod 1. YF037 at PIN
with the correct PIN for the 1766283 for a Mod 2.
model of 3803.

114

449066A

World Trade Only

Checkpoint
01A-B2M2 is PIN 8252126
and logic AA003 at EC
448505.

------------

Reserved

115'
116

Description

845958

MLM Update

\ 196

Maintenance Logic
Manuals dated 9 11/79
EC 845958.

BIBLIOGRAPHY
IBM 3803-1/3420 Magnetic Tape Subsystems; Component Description, Order Number
GA32-0020, for functional descriptions of the IBM 380.3-1 Control Unit and the IBM
3420 Magnetic Tape Units, Models 3, 5, and 7.
IBM 3803-2/3420 Magnetic Tape Subsystems; Subsystem Description, Order Number
GA32-0021, for functional descriptions of the IBM 3803-2 Control Unit and the IBM
3420 Magnetic Tape Units, Models 4, 6, and 8.
IBM System/360 and System/370 Magnetic Tape Units and Controls; Physical Planning
Template, Order Number GX22-6855, for information and diagrams regarding installation of the IBM 3803-3420 Magnetic Tape Subsystem.
IBM 3803-1/3420 Magnetic Tape Subsystem; Installation Manual, Order Number
SY32-5026, for information and checklists for field installation and checkout of the subsystem.
IBM 3420 Operator's Guide Card, Order Number G232-0003, for information about
operating the tape units.
IBM System/360/370 Reference Data; 2401-2402,2415,3410-3411, and 3420 Magnetic
Tape Units, Order Number GX35-5001, for guidelines for estimating tape processing
times and block capacities.
IBM 3803-1/3420 Magnetic Tape Subsystem; Theory-Diagrams Manual, Order Number
SY32-5024, for a training guide for the subsystem's principles of operation and for diagrams relating to training and maintenance.
IBM 3803 Tape Control Modell to Model 2 and IBM 3420 Magnetic Tape Models 3
Through 8 Customer Conversion Guide, Order Number GA32-0023.
IBM Field Engineering; Theory of Operation; Tape Subsystem Error Recording and
Analysis, Order Number SY32-5015, for an understanding of statistical error data recording programs and their messages.
IBM 3803 Magnetic Tape Subsystem, illustrated Parts Catalog, Order Number
S132-0004, for listing and illustrations of aU parts and assemblies in the control unit.
IBM 3420 Magnetic Tape Unit, Models 3, 5, and 7; Parts Catalog, Order Number
S132-0005, for listings and illustrations of all parts and assemblies in Models 3, 5, and 7,
of the tape unit.

197

BIBLIOGRAPHY (continued)
IBM 3420 Magnetic Tape Unit, Models 4, 6, and 8; Parts Catalog, Order Number
S132-0007, for listings and illustrations of all parts and assemblies in Models 4, 6, and 8
of the tape unit.
IBM System/360 and System/370 I/O Interface; Channel to Control Unit; Original Equipment Manufacturers' Information, Order Number GA22-6974, for electrical, mechanical,
and cabling information about channel/control unit interfaces.
Tape Specifications for IBM One-Half Inch Tape Drives: At 556 and 800bpi and 3200
fci, Order Number GA32-0006, for specifications and requirements for magnetic tape
to be used with IBM magnetic tape units.
IBM System/370 Reference Data, Order Number GX20-18S0, for the summary of System/
370 operation codes, condition codes, etc.
IBM Field Engineering Handbook; System/360 General, Order Number SY22-28S1, for a
pocket-sized digest of System/360 operation codes, condition codes, service aids, etc.

These publications are available from the IBM Distribution Center.
Note:

Listings of the online-test programs are available ( on microfiche) from the IBM
Program Information Department (PID). Use IBM Diagnostic Order forms,
Order Numbers ZZ2S-0S06 and ZZ2S-0507, to obtain listings, online tests, online test publications, and microfiche. Once an appropriate initial order is placed, listings are automatically updated by distributions from PID.

198

3420/3803 REFERENCE GUIDE INDEX

Abends ............................................. 35-38
Allocated Busy ........................................ .152
ALU Patches ....................................... 149-152
AMP Sensor Adjustment ................................... 54
Auto Data Transfer ........................................ 3
Belt Part Numbers ................................... 129-135
Bit Packing. . ..........................................55
Bits in Interb10ck Gap ..................................... 55
Board Layout - 3420 ................................ 117, 119
Board Ordering ..........................................42
Buffer, 32-Byte D-ata ...................................... .3
Busy, Allocated ......................................... 152
Cabling Requirements ............. '.' ..................... 172
Capstan Cleaning (and Glazed) ........................... 73, 74
Capstan Motor.......................................... 137
Capstan Open Segment .................................... 74
Capstan Part Numbers ................................... .137
Capstan Test ............................................ 74
Card Locations, 3803 001 Microprocessor ................... .139
Card Jumpering ..................................... 121-127
Channel Interface ................................... 155-161
Characteristics, Subsystem ................................. .1
Codes, Type of Recording ................................... 5
Column Vacuum Leakage Test .............................. 74
Conversion Tips (3420) ................................. 91-94
Conversion Tips (3803) ............................... 165-172
Cracked Pressure Hose .....................................75
Crease Tape Error, False (OLT) .............................. 21
Crosstalk ............................................... 27
Damage, Tape ........................................... 56
Data Flow 3420 Read/Write ....................... ' ..... 71, 72
Data Flow 3803 001 Read/Write ........................... .139
Data Flow 3803 002 Read/Write ........................... .141
DC Voltages ..................................... 87-89, 163
Degausser .............................................. 42
Developed Tape Samples.' ............................... 69, 70
Developing Tape Procedure .............................. 67, 68
Device-End, Lost .................... . .................. 151

199

3420/3803 REFERENCE GUIDE INDEX (continued)
Differences, 3803 001 and 3803 003 ......................... .3
Disconnect in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 53-159
Dropping Ready ...................................... 73-76
Dumping Tape ........................................ 73-76
ECA Checklist - 3420 ............................... 103-116
ECA Checklist - 3803 ............................... 185-196
Edge Damage, Tape .......................................56
EREP - Understanding EREP 1 ............................ 9-15
ERP (Error Recovery Program) .............................. 53
Erase Gap (ERG), Distance ................................. 69
Erase Head, Distance Relationships ........................... 69
Error Criteria ............................................. 9
Error, Permanent Read .............................. 10, 11, 53
Error, Permanent Write ........................... '" ... 10,53
Error, Temporary Read/Write ........................... .15, 53
Excessive Postamble ................................ .150, 152
Feature Codes - 3420 ..................................... 99
Feature Codes - 3803 ................................ 175, 176
Feature Identifier - 3420 ................................. 101
Feature Identifier - 3803 Modell ..................... .177, 178
Feature Installation Times - 3803 Modell and 2........... 179-184
Forward/Backward Ratio Test ........................... 56,57
Friend (OLT T0200A) .................................... 11
Glazed Capstan .......................................... 73
Group Coded Recording (6250BPI) ......................... 5,8
Head, Distance Relationships ............................... 69
Head Pin Layout ...................................... 71,72
Head Wear Test ....................................... 56,57
Holley Monitor Trap ..................................... 157
Interblock Gap, Noise In .................................. .5 5
Interlock Gap Size ........................................ 69
Interface, Channel. .................................. 155-161
Interrupted, Unexpected .................................. 151
IRD PEP Specialists ...................................... .45
J umpering, AIL2 .................................... 121-127
Layout, Al Board ................................... 117, 119
Leaking Transfer Valve Leakage Test ......................... 75
Leaking Vacuum Column Door .............................. 74
Library Quality ......................................... .49

200

3420/3803 REFERENCE GUIDE INDEX ( continued)
Locations, Microprocessor Cards - 3803 Modell ............... 139
Locations, Microprocessor Cards - 3803 Model 2 ............... 141
Magnetic Tape Adapter (MTA) ............................... 3
Magnetic Tape General Information ......................... .47
Master Signal Level Tape ..................... : ............ .42
Master Skew Tape ....................................... .41
Media Related Problems ................................ 51, 52
Microprocessor Card Interchange List ....................... 145
Microprocessor Card Locations - 3803 Modell ............... 139
Microprocessor Instruction_Format ......................... 143
MLM, What is Where .................................. .31, 34
Model 3 and Modell (3803) Differences ....................... 3
Monitor, Holley ........................................ .157
Motion Service Techniques .............................. 73-77
MST Board Ordering ..................................... .42
'Noise in Interblock Gap ................................... 55
NRZI .............................................. 3,5,7
NRZI Tape Path ........................................ 101
NTF (No Trouble Found) Checklist, Power ....................85
NTF, Read/Write......................................... 66
NTF, Tape Motion ....................................... 77
Online Tests (OLTs) ................................... 27-29
Part Numbers, Common .............................. 129-137
Partially Erased Records ................................... 73
Patches ........................................... 149-152
Patches, Tips ....................................... 145-147
PE ................................................... 5,7
PEP Specialists, IRD ..................................... .45
Permanent Errors ........................................ 53
Phase Shift ....................................... 58-59, 62
PM Schedule - 3420 ................................... 95-98
PM Schedule - 3803 ..................................... 173
Pneumatic Belts (Part Numbers) ........................ 129-135
Pneumatic System Diagrams ............................. 79, 81
Postamble, Excessive ................................. 150, 152
Power Check ............................................ 83
Power No Trouble Found Check List ......................... 85
Power Service Techniques ............................... 83, 84
Power Supplies ....................................... 87-89
Power Supply DC Voltages .......................... 87-89, 157
Power Supply Part Numbers ............................... 136
Power System, Modified 90XXX......................... 88, 132
Pressure Hose, Cracked .................................... 75
201

3420/3803 REFERENCE GUIDE INDEX (continued)
Quality, Tape ........................................... 49
Ratio Test, Read Forward/Backward .................... ; .56, 57
Read Amplitude Adjustment. .............................. .54
Read Data Flow - 3420 ................................71 ~ 72
Read Data Flow - 3803 Modell .......................... .139
Read Data Flow - 3803 Model 2 ..•......................... 141
Read Error, Permanent .............................. 10, 11, 53
Read/Write Errors ................................. .1 0, 11,53
Read/Write Head (Distance Relationships) ..................... 69
Read/Write Head (Pin Layout) ........................... 71, 72
Read/Write He(J.d (Wear Test) ........................... .56,57
Read/Write No Trouble Found Checklist .............' ......... 66
Read/Write Service Techniques ........................... 53-63
Read Only Tape ......................................... 20
Ready, Dropping ...................................... 73-76
Recording Philosophy .................................... 5-8
Reel Board and Motor Part Numbers ........................ .136
Resistor, Tie Up/Tie Down ................................ .43
RPQ ................................................. 178
ROS Patch Card ........................................ 145
ROS Patches ............................... : ....... 149-152
SAGC ................................................. 62
Sales Feature Codes - 3420 ................................ 99
Scopjng Procedures, Phase Shift ..........................58, 59
Scoping Procedures, Sense Bits .............................. 17
Sense Bytes .......................................... 17-19
Sense Analysis ........................................ 20-26
Service Techniques, Power .............................. 83, 84
Service Techniques, Read/Write .......................... 53-63
Service Techniques, Tape Motion ......................... 73-77
Short Gaps ............................................. 69
Slipping Tape ......................... '.' ................ 54
Software Zaps ...................................... 153, 154
Staggered Wraps ......................................... .51
Status Byte ............................................ 17-19
Status Identifier (All Models) ............................. .1 0 1
Stress Tape ...................................... 29, 39, 166
Subsystem Characteristics ................................... 1
Tape Damage ............................................ 56
Tape Developing Procedure .............................. 69, 70
Tape, Magnetic .......................................... 48
Tape Mark, Missing ...................................... .35
Tape, Master Signal Level ................................. .42

202

3420/3803 REFERENCE GUIDE INDEX (continued)
Tape, Master Skew ...................................... .42
Tape Motion No Trouble Found Checklist .....................77
Tape Motion Service Techniques .......................... 73-76
Tape Runaway ......................................... 149
Tape Slipping ........................................... 54
Tape Winds Uneven ....................................... 51
Temporary Errors ...................................... 9,53
Tie Up/Tie Down Resistors ................................ .43
Tools and Test Equipment .............................. 39-43
Transfer Valve Leaking .................................... 75
Transfer Valve Leaking - Part Numbers ...................... 137
Turn Around Delay ..................................... .152
Unexpected Interrupt .................................... 151
Vacuum Column Door Leaking .............................. 74
Vacuum Test ............................................ 75
Velocity Patch.......................................... 152
Voltages DC ..................................... 87,89,163
Write Data Flow - 3420 ................................... 71
Write Data Flow - 3803 ................................. .139
Write Error: ........................................ .1 0,53
Z Folds ................................................ 52
Zaps, Software .................................... .l53, 154

203

3429/3803 REFERENCE GUIDE (Form Number S229-6019-2
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