39018 0_SA850_851_Service_Manual_Dec80 0 SA850 851 Service Manual Dec80
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39018-0_SA850_851_Service_Manual_Dec80 39018-0_SA850_851_Service_Manual_Dec80
User Manual: 39018-0_SA850_851_Service_Manual_Dec80
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TABLE OF CONTENTS
Section
Page
I. THEORY OF OPERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-1
1.1 General Operations .........................' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-1
1.1.1 HeadPositioning ....... , .................................. , .. , ............ 1-1
1.1.2 Diskette Drive Spindle ., ........................................... , ........ 1-1
1.1.3 Read/Write Heads , ............. , ...................................... ,... 1-2
1.2 Recording Format ...............................................'.,............. 1-3
1.2.1 Bit Cell ., ............. , ......... , ................................... ,.... 1-3
1.2.2 Byte , ........................................ , .... , .. ,." ............ ,.. 1-3
1.2.3 Recording Format (Double Density) ........................ , .......... , . . . . . . .. 1-4
1.2.3.1 Rules of Encoding, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-5
1.2.4 Tracks ... , ..... , , ..... , ..... '" .................. '" ..................... 1-6
1.2.5 Track Format .... , ....................................... , , . . . . . . . . . . . . . .. 1-6
1.2.5.1 Sector Recording Format ............................ , . . . . . . . . . . . . . . .. 1-6
1.2.5.2 Soft Sector Recording Format ................................. , . . . . . . .. 1-6
1.2.6 Typical Track Index Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. 1-6
1.2.6.1 ............................... '.. '. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-8
1.3 Track Accessing .... , . , " ........................................................ 1-12
1.3.1 , ............. , .......................................................... 1-12
1.3.2 .............. , ... , ...................................................... 1-12
1.3.2.1 ........ ,., ...........................•................... , ........ 1-12
1.3.3 Actuator Control Logic ...................................................... 1-12
1.3.3.1 Power On Reset ..................................................... 1-12
1.3.3.2 Forward Seek ...................................................... 1-12
1.3.3.3 Reverse Seek ...................................................... 1-14
1.3.4 Track Zero Indicator, ................................, ....................... 1-14
1.4 Read/Write Operations. , . , ....................................................... 1-16
1.4.1 " .. , ... , ...... , ......... , ............ ,.................................. 1-16
1.4.2 .. , .......... ,." ................................................... , .... ·1-16
1.4.3 ........................................................................ i1-16
1.4.4 , ........... ,.,., ....................................................... :1-16
1.4.5 , .. , .. , ... , ... ,', ....................................................... 1-16
1.5 Read/Write Head .. , .. , , . , ...................................................... 1-18
1.5.1 .. , ........... ,", ........................ '. , ............................. 1-18
1.5.2 , .. , . " " . , .... " ....................................................... 1-18
1.5.3 , .. , .. , ... , .......................................................... , .. 1-18
1.5.4 .. , ......... ,.,., ....................................................... 1-18
1.6 Write Circuit Operation (Figure 31) ............................................... , .. 1-19
1.6.1 ............. "" ........................................................ 1-19
1.6.2 ., .. , ... , .... ,." ....................................................... 1-19
1.6.3 .......... , ... , .......................................................... 1-19
1.6.4 ...... '.............................. , ................................... 1-19
1.7 Read Circuit Operation (Figure 32) .................................................. 1-20
1.7.1 ..,...,.,.."....,................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-20
1.7.2 .. , .. , ....... " ............................................... , .. , ...... 1-20
1.7.3 ........ ,., .. " ...... , .................................................. 1-20
1.8 Interface, , . , ... , . , , , . , ....... , .. , ...................................... , ...... 1-21
1.8.1 J1/P1 Connector, ... " .. , , ................................................. 1-21
1.8.2 AC Power, . , , , .. , ............................................. , , ......... 1-21
1.8.3 DC Power .. , . , ........... , , ........................ , ............ , . . . . . . . . 1-21
1 .8.4 Output Lines, ............... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21
II. MAINTENANCE .. , ... , ..... , ...... , . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-1
2.1 Maintenance Features .......... , ........................................ ,...... 2-1
2.1.1 Alignment Diskette .... , .. , ......................... , . . . . . . . . . . . . . . .. . . . ... 2-1
2.1.2 SA809 Exerciser ... , . , , .. , ......................... , .... , ...... , , , . . . . . . .. 2-1
2.1.3 Special Tools .,., , ...... " .. , ... , ................ ,.', .... , .... , ....... ' " . 2-1
TABLE OF CONTENTS CON'T.
2.2 Diagnostic Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-1
2.2.1 Introduction.............................
.......................
2-1
2.2.2 "Soft Error" Detection and Correction . . . . . . . . . ..
... . . . . . . . . . . . . .
2-2
2.2.3 Write Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
........
2-2
2.2.4 Read Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ....
..........
2-2
2.2.5 Seek Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-2
2.2.6 Test Points 850/851 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-3
2.2.7 Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-3
2.2.7.1 .................................
. ...................... '
2-3
2.2.7.2 .......
..........................................
2-4
2.2.7.3 J3/P3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-4
2.2.7.4 .......
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-5
2.2.7.5 J5/P5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-5
2.2.7.6 J6/P6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. 2-5
2.3 Preventative Maintenance ......................................
.......
2-5
2.3.1 Introduction.............................................................. 2-5
2.3.2 Preventive Maintenance Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-5
2.3.3 Cleanliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. 2-6
2.3.4 Cautions ................................................................ 2-6
2.4 Removals, Adjustments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. 2-6
2.4.1 Motor Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-6
2.4.1.1 Drive Motor Assembly: Removal and Installation. . . . . . . . . . . . . . . . . . . . . .
2-6
2.4.1.2 Motor Drive Pulley ........................ '. . . . . . . . . . . . . . . . . . . . . . . . .. 2-6
2.4.2 Head Cover Shield Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-6
2.4.3 Cartridge Guide Access .................................................... 2-7
2.4.4 Sectorllndex LED Assembly: Removal and Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-7
2.4.5 Write Protect Detector .................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-7
2.4.5.1 Write Protect Detector: Removal and Installation. . . . . . . . . . . . . . . . . . . . . . . . .. 2-7
2.4.5.2 Write Protect Detector Adjustment .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-7
2.4.6 Head Load Mechanism Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. 2-8
2.4.6.1 Head Load Mechanism: Removal and Installation. . . . . . . . . . . . . . . . . . . . . . . . .. 2-8
2.4.6.2 Head Load Mechanism Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 2-8
2.4.7 Index/Sector Photo Transistor Assembly ....................................... 2-10
2.4.7.1 Index/Sector Photo Transistor Assembly: Removal and Installation ............ 2-10
2.4.7.2 Index/Sector Adjustment ............................................. 2-10
2.4.8 Spindle Assembly ......................................................... 2-10
2.4.8.1 Clamp Hub Removal ................................................. 2-11
2.4.9 Cartridge Guide ........................................................... 2-11
2.4.9.1 Cartridge Guide Removal ............................................. 2-11
2.4.9.2 Cartridge Guide Adjustment .................... " ...................... 2-11
2.4.10 Head Amplitude Check ..................................................... 2-12
2.4.10.1 Head Actuator Assembly: Removal and Installation ....................... 2-12
2.4.10.2 Head Penetration Adjustment ........................................ 2-13
2.4.10.3 Head Radial Alignment .............................................. 2-19
2.4.10.4 Read/Write Heads Azimuth Check ..................................... 2-19
2.4.11 Door Lock Solenoid and In Use LED Assembly Removal ........................... 2-20
2.4.12 Track 00 Detector: Removal and Installation ..................................... 2-22
2.4.12.1 Track 00/76 Stop Adjustment. . . . . . . . . . . . . . . . . . . . . . .
. ............. 2-22
2.4.12.2 Track 00 Detector Assembly Adjustment ....................... , ........ 2-22
2.4.13 Front Plate Assembly Removal. . . . . . .
. ............................... 2-22
III. FLOW CHARTS ....................................
........
3-1
IV. LOGIC DIAGRAMS. . . .
.......
.........
........
. ............ 4-1
V. PHYSICAL LOCATIONS. . . .
............
. . . . . . . . . . . .. 5-1
VI. ILLUSTRATED PARTS CATALOG. . . . . . .
. . . . . . . . . . . . . . . . . . . . . . .. 6-1
VII. SCHEMATIC DIAGRAMS. . .
. .... ' .
...........
. . . . . . . . .. 7-1
ii
LIST OF ILLUSTRATIONS
Figure
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
SA850/851 Functional Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-2
Bi-Compliant Read/Write Head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-2
Data Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-3
Bit Cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.........
. ..... 1-3
B~e ...............................................
.........
1~
Data Bytes . . . . . . . . . . . . . . . . . . . . . . . . . .
......................
1-4
FM, MFM and M2FM Encoding. . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-5
SA801 Sector Recording Format . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-6.
MFM Track Format Comparison ............
. ............................ , 1-7
Index Address Mark FM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-7
10 Address Mark FM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-9
Data Address Mark FM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
1-9
Deleted Data Address Mark FM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-9
MFM Index Address Mark.. ...... .................. ..... ... ...... ...
. .. 1-10
MFMIDAddressMark..... ........ ....
.................. ....
.1-10
MFM Data Address Mark .................................................... 1-10
MFM Deleted Data Address Mc:uk ............................................. 1-11
M FM I ndex Pre Address Mark ................................................ 1-11
M FM Pre I DlData Address Mark ............................. : ................ 1-11
Activator Control Logic ...................................................... 1-13
Count 0 .................................................................. 1-15
Count 1 .................................................................. 1-15
Count 2 .................................................................. 1-15
Count 3 .................................................................. 1-15
Byte .................................................................... 1-16
Basic Read/Write Head ..................................................... 1-17
Recorded Bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. .. 1-17
Reading a Bit ............................................................. 1-17
1 F and 2F Recording Flux and Pulse Relationship ................................. 1-18
Read/Write Heads ......................................................... 1-18
Write Circuit Functional Diagram .............................................. 1-19
Read Circuit Functional Diagram .............................................. 1-20
Data Separation Timing Diagram. . . . .
. ................................... 1-21
Interface Connections ...................................................... 1-22
Interface Signal Driver/Receiver .............................................. 1-23
Head Load Mechanism Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-9
Head Load Timing ......................................................... 2-9
Head Penetration Tools ..................................................... 2-13
Dial Indicator ............................................................. 2-14
Penetration Plate Installation ................................................. 2-15
Dial Indicator Installation .................................................... 2-16
Installation Check .......................................................... 2-17
Correct Penetration ........................................................ 2-17
Penetration Adjustment ..................................................... 2-18
Head Radial Alignment ...................................................... 2-20
Motor Plate ............................................................... 2-20
Azimuth Burst Patterns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
. .... 2-21
~ .........................................................................
49.
50.
&2
........................................................................ 6-5
. ............................. ,................................ ........ 6-7
iii
SECTION I
THEORY OF OPERATIONS
1.1 GENERAL OPERATIONS
The SA850/851 Diskette Drive consists of read/write and control electronics, drive mechanism, read/write
heads, track positioning mechanism, and removable Diskette. These components perform the following
functions:
•
Interpret and generate control signals.
•
Move read/write heads to the desired track.
•
Read and write data.
The relationship and interface signals for the internal functions of the SA850/851 are shown in Figure 1.
The Head Positioning Actuator positions the read/write heads to the desired track on the Diskette. The Head
Load Actuator loads the read/write heads against the Diskette and data may then be recorded or read from
the Diskette.
The electronics are packaged on the PCB. The PCB contains:
1.
Index Detector Circuits (Sector/Index for SA851).
2.
Head Position Actuator Driver
3.
Head Load Solenoid Driver
4.
Read/Write Amplifier and Transition Detector.
5.
Data/Clock Separation Circuits (SA851).
6.
Write Protect
7.
Drive Ready Detector Circuit.
8.
Drive Select Circuits.
9.
Side Select Circuit.
10.
In Use and Door Lock Circuits
11.
Write Current Switching/Read Compensation
1.1.1 HEAD POSITIONING
The read/write heads are accurately positioned by a Fasflex™ metal band/stepping motor actuator system.
A precision stepping motor is used to precisely position the head/carriage assembly through the use of a unique metal band/capstan concept. Each 3.60 rotation of the st'epping motor moves the read/write head one
'
track in discrete increments.
1.1.2 DISKETTE DRIVE SPINDLE
The Diskette drive motor rotates the spindle at 360 rpm through a belt-drive system. 50 or 60 Hz power is accommodated by changing the drive pulley and belt. A registration hub, centered on the face of the spindle,
positions the Diskette. A clamp that moves in conjunction with the latch handles fixes the Diskette to the
registration hub.
1-1
AEADDATA
SEP DATA IFMI
READ
LOGIC
SEP CLOCK (FMI
WRITE CURRENT
WRITE DATA
WRITE GATE
WRITE
LOGIC
WRITE PROTECT
PCWER ON RESET
SIDE SELECT
IN USE LED
HEAD LOAD IOPTIONAL!
STEP
DIRECTION/SIDE SELECT (OPTIONAL)
DRIVE SELECT
TRACK 00
INDEX
READY
SecTOR (851)
TRACK 00 LED
ALTERNATE UO (3 LINES)
STEPPER +A
TWO SIDED (OPTIONAL)
srFPPER-A
DISK CHANGE
E
R-B
INDEX DETECTOR
FIGURE 1. SA850/851 FUNCTIONAL DIAGRAM
1.1;3 READ/WRITE HEADS
The proprietary heads are a single element ceramic read/write head with straddle erase elements to provide
erased areas between data tracks. Thus normal interchange tolerances between media and drives will not
degrade the signal to noise ratio and insures diskette interchangeability.
The read/write heads are mounted on a carriage which is positioned by the Fasflex™ actuator. The head
carriage assembly utilizes a combination flexured/rigid head mounting system. This allows the flexured head
to load the media against its rigidly mounted counterpart (see Figure 2).
The diskette is held in a plane perpendicular to the read/write head by a platen located on the base casting.
This precise registration a'ssures perfect compliance with the read/write heads. The read/write heads are in
direct contact with the diskette. The head surface has been designed to obtain maximum signal transfer to
and from the magnetic surface of the diskette.
FIGURE 2. BI-COMPLIANT READ/WRITE HEAD
1-2
1.2 RECORDING FORMAT
The format of the data recorded on the Diskette is totally a function of the host system. Data is recorded on
the diskette using frequency modulation as the recording mode, i.e., each data bit recorded on the diskette
has an associated clock bit recorded with it, this is referred to as FM encoding. Data written on and read
back from the diskettes takes the form as shown in Figure 3. The binary data pattern shown represents a
101.
1.2.1 BIT CELL
As shown in Figure 4, the clock bits and data bits (if present) are interleaved. By definition, a Bit Cell is the
period between the leading edge of one clock bit and the leading edge of the next clock bit.
CLOCK BITS
t---
BIT CELL---I
FIGURE 3. DATA PATIERN
~
~
....B_IT_S_ _
I
DATA BITS
FIGURE 4. BIT CELL
1.2.2 BYTE
A Byte, when referring to serial data (being written onto or read from the disk drive), is defined as eight (8)
consecutive bit cells. The most significant bit cell is defined as bit cell 0 and the least significant bit cell is
defined as bit cell 7. When reference is made to a specific data bit (Le., data bit 3), it is with repsect to the
corresponding bit cell (bit cell 3).
During a write operation, bit cell 0 of each byte is transferred to the disk drive first with bit cell 7 being
transferred last. Correspondingly, the most significant byte of data is transferred to the disk first and the
least significant byte is transferred last.
When data is being read back from the drive, bit cell 0 of each byte will be transferred first with bit cell 7 last.
As with reading, the most significant byte will be transferred last from the drive to the user.
Figure 4 illustrates the relationship of the bits within a byte and Figure 6 illustrates the relationship of the
bytes for read and write data.
1-3
MSB
LSB
-----------------------B~----------------------BINARY REPRESENTATION OF:
DATA BITS
o
o
.0
CLOCK BITS
HEXADECIMAL
REPRESENTATION
OF:
DATA BITS
CLOCK BITS
FIGURE 5. BYTE
I
f
BIT CELL 0 OF BYTE 0 IS
FIRST DATA TO BE SENT
TO THE DRIVE WHEN
WRITING AND FROM THE
DRIVE WHEN READING
BIT CELL 7 OF BYTE 17 IS
LAST DATA TO BE SENT TO
THE DRIVE WHEN WRITING
AND FROM THE DRIVE
WHEN READING
FIGURE 6. DATA BYTES
1.2.3 RECORDING FORMAT (DOUBLE DENSITY)
Double capacity can be obtained by use of MFM (modified frequency modulation) and M2FM (modified,
modified frequency modulation) rather than FM (frequency modulation) which is the standard method of encoding data on the diskette.
The differences between FM, MFM and M2FM encoding are shown in Figure 7. Note that MFM and M2FM
result in a 1 to 1 relationship between the "flux changes per inch" and the bits per inch recorded on the
diskette. This also results in a doubling of the data transfer rate, from 250 to 500 KBS, when compared to
FM.
Data error rate performance equal to standard capacity diskettes using FM encoding can be achieved by using:
•
The SA850/851 diskette drive with its proprietary ceramic/ferrite read/write head.
•
Phase locked loop (VFO) data separator
•
Write precompensation.
Provision of the phase locked loop data separator and write precompensation circuitry is the responsibility
of the user of the SA850/851 diskette drive.
Shugart Associates will provide design information, as required, to SA850/851 users who desire to incorporate double capacity diskette drives in their products.
The bit cell for MFM and M2FM encoded data is one half the duration of the bit cell for FM encoded data.
Also, unlike FM, and MFM and M2FM bit cell does not always contain a clock bit at its leading edge. This Jack
of clock bit makes data separation more complex. Also, the window size is half the FM window size, which
results in less tolerance to bit shift. The only reliable method to separate MFM and M2FM encoded data is
through use of a phase locked loop (VFO) type of data separator. The VFO, once synchronized, tracks the
data and generates clock and data windows, improving the bit shift tolerance over the conventional "hard"
data separators commonly used in FM recording, which use windows of fixed timing.
1-4
1.2.3.1 RULES OF ENCODING
FM Encoding:
•
Write data bits at the center of the bit cell.
•
Write clock bits at the leading edge of the bit cell.
MFM Encoding:
•
Write data bits at the center of the bit cell.
•
Write clock bits at the leading edge of the bit cell if:
1) There is no data bit written in the previous bit cell, and
2) There will be no data bit written in the present bit cell.
M2FM Encoding:
•
Write data bits at the cerlter of the bit cell.
•
Write clock bits at the leading edge of the bit cell if:
1) There is no data bit or clock bit written in the previous bit cell, and
2) There will be not data bit written in the present bit cell.
NOTE: In M2FM/MFM, the write oscillator frequency is doubled, while maintaining the same flux changes per
inch as FM. Thus, the bit cell in M2FM/MFM is 1/2 that in FM. Data transfer rate is also doubled, since a
1 to 1 relationship exists between flux changes per inch and bits per inch (2 to 1 in FM).
BIT
CELLS
I
I~
____
I __
I
~
______
~
______
o
~
______
~
______
o
~
____
o
o
~~
____
~
______- L______
~
I
I
'21
D
D
D
D
D
11
FM
_
I
4p.sec
2p.
seCr
~~LLS L-_1~1__1-L1__1-LI_o~I~1~I~o~l~o~l~o~~~
MFM
o
D
D
D
D
D
D
D
D
D
_I
11
4/31
H
,
,,
,
,
,,
,-
, ,-
,
I-4/51
FIGURE 7. FM. MFM AND M2FM ENCODING
1-5
,
,,
,
,
,,
,
,,
,-
,
,
,,
,-
1.2.4 TRACKS
The SA850/851 drive is capable of recording up to 154 tracks of data. The tracks are numbered 0-76 for each
side. Each track is made available to the read/write heads by accessing the head with a stepper motor and
carriage assembly and selecting the desired side of the diskette. Track accessing will be covered in Section
3.
Basic Track Characteristics:
No. Data bits/track Single Density
No, Data bits/track Double Density
Index Pulse Width
Index/Sector Pulse Width
(SA851 only)
41,300 bits
82,600 bits
1.8 ± .6 ms
.4 ± .2 ms
1,2,$ TRACK FORMAT
Tracks may be formatted in numerous ways and is dependent on the using system. The SA850/851 use index
and sector recording formats respectively.
1.2.5.1 SECTOR RECORDING FORMAT
In this Format, the using system may record up to 32 sectors (records) per track. Each track is started by a
physical ,index pulse and each sector is started by a physical sector pulse. This type of recording is called
hard sectoring. Figure 8 shows a typical Sector Recording Format for 1 of 32 sectors.
_______----Ir
I
DATA
SYN·
72 BITS-+---...6
MIN
WRITE
TURN ON
CLOCK
I
DATA IDENTIFIER·
40 BITS MAX
112 BITS
MAX - . - - - - 1 0 4 0 BITS
.---------5.2
72 BITS
MAX---~~MIN
± .30MS--------.. ~1
FIGURE 8. SA801 SECTOR RECORDING FORMAT
1.2.5.2 SOFT SECTOR RECORDING FORMAT
In this Format, the using system may record one long record or several smaller records. Each track is
started by a physical index pulse and then each record is preceded by a unique recorded identifier. This type'
of recording is called soft sectoring.
'1.2.6 TYPICAL TRACK INDEX FORMAT
Figure 9 shows a track Format, which is IBM compatible, using index Recording Format with soft sectoring.
1-6
~______~I~N~D~E~X_______________________________________________________________________
MFM 10416 BYTES
REPEAT FOR EACH RECORD
G4A
I
INDEX
SYNC
4E
00
80
12
80
12
80
12
I
PRE
I. AM
I.
AM
ITl
FC
3
I
Gl
10
SYNC
4E
00
50
12
SO
12
50
12
I
PRE
10 AM
m
I
AM 110
FE
I
CRC
mm
4
I I
I
I I
m m
PRE
DATA AM
I CRC I W.G·I
OFF G3
G2
DATA
SYNC
4E
00
22
12
1024
115
654
22
12
512
83
400
BYTES/IS REC.
22
12
256
53
598
BYTES/26 REC.
AM
DATA
40
~
4E
4E
G4B
4E
DATA
BYTES/8 REC.
UPDATE WRITE
CD
00
3 bytes C2 with unique clock pattern 14
3 bytes A 1 with
uniq~e clock
pattern OA
@]
@J
Generated by CRe generator which should be equivalent to CCITT VHl
([)
1 byte of FB or
Track number., head number, sector, record length
Fa
FIGURE 9. MFM TRACK FORMAT COMPARISON
C
D
C
D
D
C
D
D
c
D
C
C
BIT CEllO BIT CELL 1 BIT CEll 2 BIT CELL 3 BIT CELL 4 BIT CELL 5 BIT CELL 6 BIT CEll 7 BIT CEllO
~~-------------------INDEXADDRESSMARKBYTE--------------------~~
HEXADECIMAL
REPRESENTATION OF:
BINARY
REPRESENTATION OF:
o
DATA BITS
CLOCK BITS
o
o
FIGURE 10. INDEX ADDRESS MARK FM
1-7
o
DATA BITS
FC
CLOCK BITS
D7
1.2.6.1
Index is the physical detector indicating one revolution of the media and is used to initiate format
operations, generate the Ready signal in the storage device, insure one complete revolution of the media
has been searched, and for a deselect storage device signal after a certain number of revolutions.
Gap 1-
G4A is from the physical index address mark sync and allows for physical index variation,
speed variation and interchange between Storage Devices.
Sync is a fixed number of bytes for Separator synchronization prior to the address mark. It
includes a minimum of two bytes plus worst case Separator sync up requirements.
Index Pre Address Mark (MFM) . Three bytes of C2 with unique clock bits not written per
the encode rules. Refer to Figure 18.
Index Address Mark (FM) . is a unique byte to identify the index field and is not written per
the encode rules. Refer to Figure 10.
Index Address Mark (MFM) . is one byte of FC and it is written per the encode rules.
Refer to Figure 14.
G1 is from index address mark to ID field address mark sync.
ID Field-
Sync is a fixed number of bytes for Separator synchronization prior to AM. Includes a
minimum of two bytes plus worst case Separator sync up requirements.
ID Pre Address Mark (MFM) . Three bytes of A1 with unique clock bits not written per the
encode rules. Refer to Figure 18.
ID Address Mark (FM) . is a unique byte to identify the ID field and not written per the encode rules. Refer to Figure 11.
ID Address Mark (MFM) . is one byte of FE and it is written per the encode rules. Refer to
Figure 15.
ID· is a four byte address containing track number, head number, record number, and
record length.
CRC . is two bytes for cyclic redundancy check.
Gap 2-
Gap from IDCRC to data AM sync and allows for speed variation, oscillator variation and
erase core clearance of IDCRC bytes prior to write gate turn on for an update write.
Data Field - Sync is a fixed number of bytes for Separator synchronization prior to the AM. Includes a
minimum of two bytes plus worst case separator sync up requirements.
Pre Data Address Mark (MFM) . Three bytes of A1 with unique clock bits not written per
the encode rules. Refer to Figure 19.
Data Address Mark (FM) . is a unique byte to identify the Data Field and it is not written
per the encode rules. Refer to Figure 12.
Data Address Mark (MFM) . is one byte of FB or F8 and it is written per the encode rules.
Refer to Figure 17.
Data· is the area for user data.
CRC . is two bytes for cyclic redundancy check.
WG OFF (Write Gate Off) . is one byte to allow for the Write Gate turn off after an update
write.
1-8
c
c
ell CEll 7
eITCEll~
0
C
0
0
SIT CELL I
SIT CEll 7
C
0
0
C
0
C
0
C
., "' r.=r.=r.=
BIT CEll J
C
BIT CellO
10 AODRESS MARK 8YTE
BINARY
REPRESENTATION OF:
HEXADECIMAL
REPRESENTATION OF:
o
DATA BITS
o
CLOCK BITS
o
DATA BITS
FE
o
CLOCK BITS
C7
FIGURE 11. ID ADDRESS MARK FM
C
C
o
C
o
""S·'-l-C-E-l-l")'"+-S·'-T-C-E-l-l·f)+-B'""-T-C-EL-l-'
o
o
o
o
C
C
C
o
C
C
~4:"I-T-C-E-ll-:"t"':'"'IT-CE-l-l-~0!""~"8-IT-C-E-l-l""5O+-S-'T-C-E-l-l-'~
:,""':
I
~----------------OATAAOORESSMARK8YTE--------------______~~
BINARY
REPRESENTATION OF:
HEXADECIMAL
REPRESENTATION OF:
o
DATA BITS
o
CL,.OCK BITS
o
DATA BITS
FB
o
CLOCK BITS
C7
FIGURE 12. DATA ADDRESS MARK FM
C
C
C
o
o
o
o
... ~ . .~~
81T CELL)
Sil CELL 0 ISIl CEllI 1811 CEll 71 81T CEll J I BIT CEll4181T CELL 5
t----------------__
c
C
C
C
C
""""1.:= ., "' '
--OElETEO OATA AOORESSMARK BYTE----------__- - - - - - - ;
HEXADECIMAL
REPRESENTATION OF:
BINARY
REPRESENTATION OF:
o
DATA BITS
CLOCK .BITS
o
o
o
o
o
FIGURE 13. DELETED DATA ADDRESS MARK FM
1-9
DATA BITS
Fa
CLOCK BITS
C7
o
BIT
o
~ELL
I
BIT
o
I
~ELL
BIT
o
o
I
~ELL
BIT
I
~ELL
"'--~--------INDEX
I
~ELL
BIT
o
o
C
I
BIT. CELL
5
BITCELl./
B.'TCEL:J
,6
7
ADDRESS MARK
BINARY
REPRESENTATION OF:
HEXADECIMAL
REPRESENTATION OF:
o
DATA BITS
o
CLOCK BITS
FC
o
01
FIGURE 14. MFM INDEX ADDRESS MARK
o
BIT
o
~ELL
I
BIT
o
I
~ELL
o
I
~ELL
BIT
~ELL
BIT
o
o
I
I
~ELL
BIT
o
I
~ELL
BIT
BIT
~ELL
I
BIT
~ELL
1......
. . _ - - - - - - - - - - MFM 10 ADDRESS MARK -----------~
BINARY
REPRESENTATION OF:
HEXADECIMAL
REPRESENTATION OF:
DATA BITS
o
CLOCK BITS
o
o
o
o
o
o
o
FE
o
00
FIGURE 15. MFM 10 ADDRESS MARK
o
BIT
~LL
I
BIT
~ELL
I
BIT
o
o
o
o
~ELL
I
~-----------
BIT
~ELL
I
BIT
~ELL
I
DATA ADDRESS MARK
BIT
~ELL
I
BIT
~ELL
I
BIT
~ELL
-----------+-1
BINARY
REPRESENTATION OF:
HEXIDECIMAL
REPRESENTATION OF:
DATA BITS
CLOCK BITS
o
o
o
o
o
o
o
o
o
FB
o
o
FIGURE 16. MFM DATA ADDRESS MARK
1-10
00
C
D
D
D
C
BIT CELL
6
BIT CELL
7
D
D
DELETED DATA ADDRESS MARK
BINARY
REPRESENTATION OF:
HEXIDECIMAL
REPRESENTATION OF:
CLOCK BITS
o
o
o
o
o
o
o
o
DATA BITS
Fa
o
03
FIGURE 17. MFM DELETED DATA ADDRESS MARK
D
D
BIT
~ELL
I ~ELL I ~ELL I
BIT
BIT
D
C
C
BIT ;ELL
I ~ELL I
BIT
BIT CELL
BIT C5ELL
6
BIT CELL
7
' - - - - - - - - - - - - PRE INDEX ADDRESS MARK -----------~
HEXIDECIMAL
REPRESENTATION OF:
BINARY
REPRESENTATION OF:
DATA BITS
CLOCK BITS
o
o
o
o
o
o
o
o
o
o
o
C2
14
FIGURE 18. MFM INDEX PRE ADDRESS MARK
D
BIT
D
~ELL
I
BIT
C
~ELL I BIT ~ELL I BIT ~ELL
I
D
C
BIT
~ELL
I
BIT
~ELL
I
BIT
~ELL I BIT ~ELL
1 - 4 - - - - - - - - - - - - PRE ADDRESS MARK
BINARY
REPRESENTATION OF:
HEXIDECIMAL
REPRESENTATION OF:
DATA BITS
CLOCK BITS
o
o
o
o
o
o
o
o
o
o
A1
o
FIGURE 19. MFM PRE ID/DATA ADDRESS MARK
1-11
OA
Gap 3 -
Gap 4 -
!
Gap from WG OFF to next 10 AM sync and allows for the erase core to clear the Data
Field CRC bytes, speed and write oscillator variation, read preamplifier recovery time and
system turn around time to read the following 10 Field.
G4B is the last gap prior to physical index and allows f()r speed and write oscillator variation during a format write and physical index variation.
1.3.0 TRACK ACCESSING
•
•
•
•
•
Carriage Actuator Motor
Actuator Control Logic
Reverse Seek
Forward Seek
Tr~ck
00 Flag
1.3.1
Seeking the read/write heads from one track to another is accomplished by selecting the desired
direction utilizing the Direction Select interface line, loading the read/write heads, and then pulsing the Step
line. Multiple track accessing is accomplished by repeated pulsing of the Step line until the desired track has
been reached. Each pulse on the Step line will cause the read/write heads to move one track either in or out
depending on the Direction Select line.
1.3.2
The Carriage Actuator Motor used on the SA850/851 is a four phase, 3.6 degree, permanent
magnet stepper motor.
.
1.3.2.1
There are four stator poles with four teeth per pole extending axially the length of the rotor. The
rotor contains 25 teeth per half, spaced 14.4 degrees apart, with each being displaced one tooth pitch
relative to each other. The rotor is permanently magnetized with one gear (half) being the north pole and the
other the south pole. The four winding per phase are those which when energized will magnetize the poles
causing th.e rotor to move v.. of a gear tooth pitch or 1 step.
1.3.3 ACTUATOR CONTROL LOGIC
In the folloWing paragraphs, refer to Figure 20.
1.3.3.1 POWER ON RESET
The Step Counter (FF A and FF B) is a modified Gray Code counter that counts 0, 1, 3 and 2. At power on, the
Step Counter is reset causing the not outputs to be active. When the door is closed and the heads loaded the
not outputs actuate the 1 and 4 drivers. With these drivers active the position zero windings are excited
causing the rotor to align as shown in Figure 21. (Note, depending on the previous state of the stator windings, the heads may move up to two tracks).
1.3.3.2 FORWARD SEEK
•
Seek forward five tracks .
•
Assuming:
Present position of the read/write heads to be track 00.
Direct Select at a minus level (from the host system).
Write Gate inactive.
Five Step pulses to be received (from the host system).
Step Counter reset (drivers 1 and 4 active).
1-12
+ STEPPER bNABlE
+ 24V
+ 24V
+ 5V
STEP
COUNTER
·DIRECTION
SELECT
Q
D
FFA
(5
C
B
D
Q
FF8
(5
C
·READ (;ATE'
·POWER ON
RESET
·TRACK 00
PHASE A
PHASE B
1_--
TRACK
00
STEP COUNT
o
01
02
03
04
3
2
0
05
06
07
08
3
2
o
09
10
11
3
2
FIGURE 20. ACTIVATOR CONTROL LOGIC
1-13
Minus Direction Select is inverted and becomes + Direction Select. Since the Step Counter is reset (low), a
high is at one input of Exclusive OR A and a low at Exclusive OR B. + Direction Select is high and inverts
both signals present at Exclusive OR's A and B, causing the input to FFB to be high.
When the first Step pulse is sent to the control logic, it is anded with -Read Gate and then clocks FF A off and
FF B on. this enables drivers 1 and 3 causing the Actuator Motor to move 3.60 in a clockwise direction, which
in turn moves the carriage assembly one track towards the center of the diskette. Figure 20 (Track 01, Count
1).
With FF A off and FF B on, a low is presented to Exclusive OR AA and B allowing + Direction Select to pass
to both FFS. Upon receipt of the next Step pulse both FFS are clocked on, enabling drivers 2 and 3. Figure 21
(Track 02, Count 3).
With both FFS on, a low is at Exclusive OR A and a high at Exclusive OR B which presents + Direction Select
to FF A. The next Step pulse clocks FF A on and FF B off enabling drivers 2 and 4. Figure 24 (Track 03, Count
2).
This process is continued until the host system stops sending step pulses at Track 05. At that time FF A is off
and FF B on enabling drivers 1 and 3. Figure 22 (Count 1).
1.3.3.3 REVERSE SEEK
•
Seek in a reverse direction five tracks .
•
Assuming:
Present position of the read/write heads to be track 05. Direction Select at a positive level (from
the host system).
Write Gate inactive.
Five step pulses to be received.
FF A is off and FF B is on, drivers 1 and 3 active.
Plus Direction Select is inverted and becomes -Direction Select. With FF A off and FF B on lows are
presented to Exclusive ORs A and B. With the first step pulse the FFS are clocked off enabling the 1 and 4
drivers causing the actuator motor to move 3.6 degrees in a counter-clockwise direction, moving the carriage one track towards the outside of the diskette. Figure 21 (Track 04, Count 0).
With both FFS off a high is presented to Exclusive OR A and a low to Exclusive OR B. the next Step pulse
clocks FF A on and FF B off enabling drivers 2 and 4. Figure 24 (Track 03, Count 2).
This process continues until the fifth Step pulse. With lows at the Exclusive ORs, and FF's are clocked off
enabling drivers 1 and 4. Figure 20 (Track 00, Count 0).
1.3.4 TRACK ZERO INDICATOR
Track 00 Pin 42 is provided to the host system to indicate the read/write heads are at track zero. The Track
Zero Flag on the carriage assembly is adjusted so that the flag covers the photo transistor at track one.
When FF A and B are clocked off the actuator moves to track zero, the Q outputs and Drive Select Internal
are anded together and then ANDed with the Track Zero detect to send the Track Zero indication to the host
system. (Figure 20)
1-14
B1
B1
A1
A2
A1
A2
B2
B2
FIGUREI21. COUNT 0
FIGURE 22. COUNT 1
B1
B1
A2
A1
A2
A1
B2
B2
FIGURE 24. COUNT 3
FIGURE 123. COUNT 2
1-15
1.4.0 READ·WRITE OPERATIONS
•
SA850/851 uses double frequency NRZI recording method.
•
The read/write heads are similar to a ring with a gap and a coil wound at some point on the ring.
•
During a write operation, a bit is recorded when the flux direction in the ring is reversed by rapidly
reversing the current in the coil.
•
During a read operation, a bit is read when the flux direction in the ring is reversed as a result of a
flux reversal on the diskette surface.
1.4.1
The SA850/851 drive uses the double-frequency (2F) horizontal non return to zero (NRZI) method
of recording. Double frequency is the term given to the recording system that inserts a clock bit at the beginning of each bit cell time thereby doubling the frequency of recorded bits. This clock bit, as well as th·e data
bit, are provided by the using system. See Figure 25.
1.4.2
The read/write heads are similar to a ring with a gap and a coil wound some point on the ring.
When current flows through the coil, the flux induced in the ring fringes at the gap. As the diskette recording
surface passes by the gap, the fringe flux magnetizes the surface in a horizontal direction. See Figure 26.
1.4.3
During a write operation, a bit is recorded when the flux direction in the ring is reversed by rapidly
reversing the current coil. The fringe flux is reversed in the gap and hence the portion of the flux flowing
through the oxide recording surface is reversed. If the flux reversal is instantaneous in comparison to the
motion of the diskette, it can be seen that the portionof the diskette surface that just passed under the gap is
magnetized in one direction while the portion under the gap is magnetized in the opposite direction. This flux
reversal represents a bit. See Figure 27.
1.4.4
During a read operation, a bit is read when the flux direction in the ring is reversed as a result of a
flux reversal on the diskette surface. The gap first passes over an area that is magnetized in one direction,
and a constant flux flows through the ring coil. The coil registers no output voltage at this point. When a flux
transition passes under the gap, the flux flowing through the ring and coil will make a 1800 reversal. This
means that the flux reversal in the coil will cause a voltage output pulse. See Figure 28.
1.4.5
Figure 29 shows the 1F and 2F recording flux transitions with pulse relationship.
c
D
c
c
D
.. ..
BINARY
REPRESENTATION
HEX
REPRESENTATION
C
C
..
.. ..
D
C
D
C
C
.. ... .. ... .. ..
.. ...
..
BIT CELL 0
BIT CELL 1
BIT CELL 2
BIT CELL 3
BIT CELL 4
BIT CELL 5
BIT CELL 6
BIT CELL 7
1
1
0
0
1
0
1
0
\~------~------~/\~------~------~/
I
A
C
FIGURE 25. BYTE
1-16
..
CURRENT
FRINGE
FLUX
- -- -
--MYLAR
BASE
OXIDE
RECORDING
SURFACE
I
(~)
DISKETTE MOTION
FIGURE 26. BASIC READ/WRITE HEAD
...
CURRENT
---
----
I
-- ------
RECORDED BIT
..
DISKETTE MOTION
FIGURE 27. RECORDED BIT
VOLTAGE PULSE
(FLUX REVERSAL IN GAP)
-- -- --
------RECORDED BIT
... DISKETTE MOTION
FIGURE 28. READING A BIT
1-17
2F
BINARY
EOUIVALENT
II
BIT CELL 0
WRITE
DRIVER'
,,'---,
WRITE
DRIVER 2
:
WRITE DATA
DISKETIE
SURFACE
IC
i
2F
0
BIT CELL 2
0
II
-:t .........
(--::c-:;-:::c"(~ ~
' I 'I ,
2F
"
,
BIT CELL ,
I ••••
I
I
D
Ic
I
I
~
BIT CELL 3
D
....
~
~
.. ~ ... ~~-~ ...... .. .....
I
I'
:
I
:
'REVERSAL~II
I
I
L....=.......... ---==::::>~,~~I ~..-:=:1I
I
:
I
I
I
I
I
I
READ
SIGNAL
,F
,r--.'. . -""",""""r--''---~ r--"---""'y
I
FLUX
j
j
READ
DATA
FIGURE 29. 1 F AND 2F RECORDING FLUX AND PULSE RELATIONSHIP
1.5.0 READIWRITE HEAD
•
The read/write heads contain two coils each.
•
When writing, the head erases the outer edges of the track to insure there is erased areas between
adjacent tracks.
1.5.1
Each of the read/write heads contain two coils. Two read/write coils are wound on a single core,
center tapped and one erase coil is wound on a yoke that spans the track being written. The read/write and
erase coils are connected as shown in Figure 30.
On a write operation, the erase coil is energized. This causes the outer edges of the track to be
1.5.2
trim erased so as the track being recorded will not exceed the .012" track width. The trim erasing allows for
minor deviations in read/write head current so as one track is recorded, it will not "splash over" to adjacent
tracks.
1.5.3
Each bit written will be directed to alternate read/write coils, thus causing a change in the direc,:,
tion of current flow through the read/write head. This will cause a change in the flux pattern for each bit. The
current through either of the read/write coils will cause the old data to be erased as new data is recorded.
1.5.4
On a read operation, as the direction of flux changes on the diskette surface as it passes under the
gap, current will be induced into one of the windings of the read/write head. This will result in a voltage output pulse. When the next data bit passes under the gap, another flux change in the recording surface takes
place. This will cause current to be induced in the other coil causing another voltage output pulse.
R/WO
II
FIGURE 30. READ/WRITE HEADS
1-18
R/W'
1.6.0 WRITE CIRCUIT OPERATION (FIGURE 31)
•
The binary connected Write Data Trigger toggles with each pulse on the Write Data line.
•
The Write Data Trigger alternately drives one or the other of the Write Drivers.
•
Write Gate allows write current to flow to the Write Driver circuits.
•
Write Current sensed allows Erase Coil current.
•
Heads are selected by grounding the appropriate center tap.
1.6.1
Write data pulses (~ock & data bits) are supplied by the using system. The Write Trigger "toggles"
with each pulse. The Q and Q outputs are fed to alternate Write Drivers.
1.6.2
Write Gate, from using system, and not Write Protect, are anded together to provide write current.
1.6.3
The output of one of the Write Drivers allows write current to flow through one-half of the
read/write coil of each head. When the Write Data Trigger toggles, the other Write Driver provides the write
current to the other half one the read/write coils.
1.6.4
When write current is sensed flowing to the Write Drivers, a signal is generated to provide trimmer
erase coil current.
I HEAD III
I
- - R/W 11
R/W01
D
Q
WRITE
DATA
TRIGGER
-WRITE DATA
C
Q
-WRITE GATE
WRITE CURRENT
FIGURE 31. WRITE CIRCUIT FUNCTIONAL DIAGRAM
1-19
I HEAD 1
I
1.7.0 READ CIRCUIT OPERATION (FIGURE 32)
•
Duration of all read operations is under control of the using system.
•
When the heads are loaded, the read signal amplitude becomes active and is fed to the amplifier.
•
As long as the heads are loaded and write gate is not active, the read signal is amplified and
shaped, the square wave signals are sent to the host system.
•
The data separator separates the read dat.a into clock pulses and data pulses (SA851 only).
1.7.1
When the using system requires data from the diskette drive, the using system must first load the
heads and select the side. With loading of the heads and write gate being inactive, the read signal is fed to
the amplifier section of the read circuit. After amplification, the read signal is fed to a filter where noise
spikes are removed. The read signal is then fed to the differential amplifier.
1.7.2
Since a pulse occurs at least once every 41's and when data bits are present once every 21's, the
frequency of the read data varies. The read signal amplitude decreases as the frequency increases. Note
the Signals on Figure 30. The differential amplifier will amplify the read signals to even levels and make
square waves out of the read signals (sine waves).
1.7.3
The data separator (SA851 only) is a single time constant separator, that is, the clock and data
pulses must fall within pre-specified time frames or windows (single density only).
C
r::-,-,
CJ--i
CDC
Jl..Jl.nIL
o
1
TPl
~NVERTER J_.---1
-READ DATA
........
~"----1
TP2
-SEP DATA
DATA
SEP
-SEPCLOCK
FIGURE 32. READ CIRCUIT FUNCTIONAL DIAGRAM
1-20
B
B
I
HEX EOUIV.
o
BINARY EOUIV.
I
\/
o
I
o
0
+ READ DATA
I
•I
·SEPDATA
I
I
I
I .
I
{g
·SEPCLK
I
I
I
+L1
I
I
U
h
I
~
I
I
I
I
I
I
I
I
U
U
I
I
I
-L
I
I
I
I
U
U
U
U
U
I
I
I
-DATA WINDOW
FIGURE 33. DATA SEPARATION TIMING DIAGRAM
1.8.0 INTERFACE
The Electrical interface between the SA850/851 drive and the host system is via three connectors. The first
connector, J1, provides the signal interface; the second connector, J5, provides the DC power; and the third
connector, J4, provides the AC power and frame ground.
1.8.1 J1/P1 CONNECTOR
Connection to J1 is through a 50 pin PCB edge card connector. The pins are numbered 1 through 50 with the
even numbered pins on the component side of the PCB and the odd numbered pins on the non-component
side. Pin 2 is located on the end of the PCB connector closest to the AC motor capacitor and is labeled 2. A
key slot is provided between pins 4 and 6 for optional connector keying. Refer to Figure 34.
1.8.2 AC POWER
The AC power to the drive is via the connector P4/J4 located on the rear of the drive and below the AC motor
capacitor. The P4/J4 pin designations are outlined below for standard as well as optional AC power.
1.8.3 DC POWER
DC power to the drive is via connector P5/J5 located on non-component side of PCB near the P4 connector.
The three DC voltages and their specifications along with their P5/J5 pin designators, are outlined below.
1.8.4 OUTPUT LINES
There are five standard output lines from the SA850, and eight standard output lines from the SA851. Also,
there are two optional output lines and eight alternate outputs available from either the SA850 or SA851. The
output signals are driven with an open collector output stage capable of sinking a maximum of 40 ma at a
logical zero level or true state with a maximum voltage of O.4V measured at the driver. When the line driver is
in a logical one or false state, the driver is off and the collector current is a maximum of 250 microamperes.
Refer to Figure 35 for the recommended circuit.
1-21
MAX FEET
10 FT FLAT RIBBON OR
20 FT TWISTED PAIR
SA850/851
Jl
2
WRITE CURRENT SWITCH
1
TWO SIDED'
.10
9
12
11
14
13
16
15
18
17
20
19
22
21
24
23
26
25
28
27
30
29
32
31
14
33
36
35
38
37
40
39
42
41
44
43
46
45
48
47
50
49
DISK CHANGE'
SIDE SELECT
IN USE'
HEAD LOAD'
INDEX
READY
SECTOR (851 ONLY)
DRIVE SELECT 1 (SIDE SELECT OPT)
DRIVE SELECT 2 (SIDE SELECT OPT)
DRIVE SELECT 3 (SIDE SELECT OPT)
DRIVE SELECT 4 (SIDE SELECT OPT)
DIRECTION SEU,CT (SIDE SELECT OPT)
STEP
WRITE DATA
WRITE GATE
TRACK 00
WRITE PROTECT
READ DATA
SEP DATA (851 ONLY)
SEP CLOCK (851 ONL Yl
-.
-
I
4:DCGND
+5 VDC
6
__ +24VDC
X
-
1
+ 24 V RETURN
2
~..:J4
ACINPUT
1
FRAME GROUND
ACINPUT
ACGND
J5
5
" S V RETURN
~~
~~
TWISTED PAIR
* These lines are alternate input/output lines and they are enabled by jumper plugs.
Not shown are pins 4, 6 and 8 which are alternate 110 pins.
FIGURE 34, INTERFACE CONNECTIONS
1-22
FRAMEGND
P4
PIN
50 Hz
60 Hz
115 V (Standard)
208/230 V
220V
110V
1
85-127 VAC
170-253 VAC
85-127 VAC
170-253 VAC
2
Frame Gnd
Frame Gnd
Frame Gnd
Frame Gnd
3
85-127 V Rtn
170-253 V Rtn
85-127 V Rtn
170-253 V Rtn
0.35 Amps
0.25 Amps
MAX
CURRENT
0.35 Amps
FREQ
TOLERANCE
0.25 Amps
±0.5 Hz
±0.5 Hz
TABLE ,:
MAX
RIPPLE (p to p)
P5
PIN
DC VOLTAGE
TOLERANCE
1
+24 VDC
± 2.4 VDC
1.0A Max*
0.85A Typ
100 mv
2
+ 24 V Return
6
+ 5 V Return
5
+ 5 VDC .
± 0.25 VDC
1.1AMax
1.OA Typ
50 mv
CURRENT
* If either customer installable option described in
sections 7.1 and 7.3 are used. the current requiremen for the + 24-VDC·is a multiple of the maximum
+ 24V current times the number of drives on the
line.
TABLE 2
MAX 10 FEET
RIBBON OR 20
FEET TWISTED
PAIR
7414
HOST
SA850
FIGURE 35. INTERFACE SIGNAL DRIVER/RECEIVER
1-23
SECTION II
MAINTENANCE
2.1.0 MAINTENANCE FEATURES
2.1.1 ALIGNMENT DISKETTE
The SA 122 Alignment Diskette is used for alignment of the SA850/851. The following adjustments can be
made using the SA122. Adjustments are checked on head zero and head one.
1.
R/W Head radial alignment using track 38.
2.
Index Photo-Detector Adjustment using tracks 01 and 76.
3.
Track 00 is recorded with standard IBM 3740 format.
4.
TK 75 has 1f
+ 2f signal.
NOTE: Caution should be exercised in using the SA 122 Alignment Diskette. Tracks 00, 01, 36, 37, 38, 39,
40, 75, and 76 should not be written on. To do so will destroy pre-recorded tracks.
2.1.2 SA809 EXERCISER
The SA809 Exerciser is built on a PCB whose dimensions are 8" x 8". The exerciser PCB can be used in a
stand alone mode or it can be built into a test station or used in a tester for field service.
The Exerciser is designed to enable the user to make all adjustments and check outs required on the
SA850/851 drives, when used with the SA 122 Alignment Diskette.
The exerciser has no intelligent data handling capabilities but can write both 1f and 2f frequencies. The exerciser can enable read in the drive to allow checking of read back signals.
2.1.3 SPECIAL TOOLS
The following specials tools are available for performing maintenance on the SA850/851.
Description
Alignment Diskette
Cartridge Guide Adj. Tool
Exerciser
.
Spanner Wrench
Head Penetration Tool Set
Part Number
SA122
50377-1
50619-0
50752-0
51218-0
2.2.0 DIAGNOSTIC TECHNIQUES
2.2.1 INTRODUCTION
Incorrect operating procedures, faulty programming, damaged diskettes, and "soft errors" created by airborne contaminants, random electrical noise, and other external causes can produce errors falsely attributed to drive failure or misadjustment.
Unless visual inspection of the drive discloses an obvious misalignment or broken part, attempt to repeat the
fault with the original diskette, then attempt to duplicate fault on second diskette.
2-1
2.2.2 "SOFT ERROR" DETECTION AND CORRECTION
Soft errors are usually caused by:
1.
Airborne contaminants that pass between the read/write head and the disk. Usually these contaminants can be removed by the diskette self-cleaning wiper.
2.
Random electrical noise that usually last for a few microseconds.
3.
Small defects in the written data and/or track not detected during the write operation that may
cause a soft error during a read.
The following procedures are recommended to recover from the above mentioned soft errors:
1.
Reread the track ten (10) times or until such time as the data is recovered.
2.
If data is not recovered after using step 1, access the head to the adjacent track in the same direction previously moved, then return to the desired track.
3.
Repeat Step 1.
4.
If data is not recovered, the error is not recoverable.
2.2.3 WRITE ERROR
If an error occurs during a write operation, it will be detected on the next revolution by doing a read operation, commonly called a "write check". To correct the error, another write and write check operation must
be done. If the write operation is not successful after ten (10) attempts have been made, a read operation
should be attempted on another track to determine if the media or the drive is failing. If the error still persists
the diskette should be replaced and the above procedure repeated. If the failure still exists, consider the
drive defective. If the failure disappears, consider the original diskette defective and discard it.
2.2.4 READ ERROR
Most errors that occur will be "soft" errors. In these cases, performing an error recovery procedure will
recover the data.
2.2.5 SEEK ERROR
1.
Actuator malfunction.
To recover from a seek error recalibrate to track 00 and perform another seek to the original track.
2-2
2.2.6 TEST POINTS 850/851
1.
2.
5.
6.
7.
11 .
12.
13.
16.
17.
18.
25.
26.
27.
28.
I.
R.
S.
Read data signal
Read data signal
Signal ground
Signal ground
Signal ground
+ Head load
-Index and 851 sector pulses (single sided disk)
-Index and 851 sector pulses (double sided disk)
+ Read data
-Data separator timing (long data window)
-Data separator timing (short data window)
+ Write protect
+ Detect track 00
+ Gated step pulses
Signal ground
-Separated index (interface)
-Ready (interface)
-Separated sector 851 (interface)
2.2.7 CONNECTORS
2.2.7.1
J1 fP1 provide the signal interface to the host system. The pin designators are as listed below.
2.
Write Current Switch
4.
Alternate I/O
6.
Alternate I/O
8.
Alternate I/O
10. Two Sided (optional)
12. Disk Change (optional)
14. Side Select
16. In Use (optional)
18. Head Load (optional)
20. Index
21. Ready
24. Sector (851 only)
26. Drive Select 1 (or Side Select Option)
28. Drive Select 2 (or Side Select Option)
30. Drive Select 3 (or Side Select Option)
32. Drive Select 4 (or Side Select Option)
34. Direction Select (or Side Select Option)
36. Step
38. Write Data
40. Write Gate
42. Track 00
44. Write Protect
46. Read Data
48. FM Sep Data (851 only)
50. FM Sep Clock (851 only)
NOTE: All odd numbered pins are ground.
2-3
2.2.7.2
J2/P2 provide control signals and power to the Head Load Actuator, the Head Position actuator
dropping resitors, In Use LED and Door Lock solenoid and the detector assemblies. The pin designators are
as listed below:
A.
B.
C.
D.
E.
F.
H.
J.
K.
L.
M.
N.
P.
R.
S.
T.
U.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
Key
+ In Use LED
+ Track 00 LED
+ Write Protected
+ Index LED
+ Door Closed
-Door Closed
Not used
-Door Locked
-Track 00
+ Write Protected
+ Index/Sector 0 Detector
+ Index/Sector 1 Detector
Key
+ Stpr Wndg/Res A
+ Stpr Wndg/Res B
-Head Load
Key
Ground
Ground
Ground
Ground
Ground
Not Used
Not Used
+ 24V Door Lock
+ 5V Track 00 Detector
+ 5V Write Protect
+ 5V Index (0 & 1) Detector
Not Used
Key
+ Stpr Res A
+ Stpr Res B
+ 24V Head Load
2.2.7.3 J3/P3
J3/P3 provides to interface to the Read/Write coils and the trim erase coils of the
magnetic recording heads. The pins are listed below:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Shield 0
Key
Read/Write
Side 0 CT
Read/Write
Erase 0
Erase 1
Read/Write
Side 1 CT
Read/Write
Key
Shield 1
01
02
12
11
2-4
2.2.7.4
1.
2.
3.
J4/P4 provide AC power and ground as listed below:
-AC Motor Power A
-Frame Ground
AC Motor Power B
2.2.7.5 J5/P5
J5/P5 provide DC power and ground as listed below:
1.
2.
+ 24 Volts DC
+ 24 Volt Ground
3.
4.
5.
6.
Not
Not
+5
+5
Return
Used
Used
Volts DC
Volts Ground Return
2.2.7.6 J6/P6
1.
2.
3.
4.
5.
+ Stpr
Key
+ Stpr
+ Stpr
+ Stpr
J6/P6 provide power to the Head Positioning actuator as listed below:
Wndg/Res B
Wndg/Res A
Wndg B
Wndg A
2.3.0 PREVENTATIVE MAINTENANCE
2.3.1 INTRODUCTION
The prime objective of any preventive maintenance activity is to provide maximum machine availability to
the user. Every preventative maintenance operation should assist in realizing this objective. Unless a
preventive maintenance operation cuts machine downtime, it is unnecessary.
Visual inspection is the first step in every scheduled maintenance operation. Always look for corrosion, dirt,
wear, binds, and loose connections. NotiCing these items during PM may save downtime later.
Remember, do not do' more than recommended preventative maintenance on equipment that is operating
satisfactorily.
2.3.2 PREVENTIVE MAINTENANCE PROCEUDRES
Details of preventative maintenance operations are listed in Table ~. During normal perventative
maintenance, perform only those operations listed on the chart for that preventive maintenance period.
Observe all safety procedures
UNIT
FREQ.
MONTHS
Read/Write Heads
N/A
No maintenance required
Actuator band,
capstan and shaft
12
Clean all oil, dust, and
dirt only if necessary
Belt
12
Base
12
Read/Write Head
12
CLEAN
OBSERVE
Do not touch or clean
Frayed or weakened areas
Clean base
Inspect for loose screws
connectors, and switches
Check for proper alignment
TABLE.3
2-5
2.3.3 CLEANLINESS
Cleanliness cannot be overemphasized in maintaining the SA850/851. Do not lubricate the SA850/851· oil
will allow dust and dirt to accumulate. To prevent damage the read/write heads should not be cleaned or
touched.
2.3.4 CAUTIONS
The heads should never touch each other. Whenever removing or installing the heads insure a clean piece
of lens tissue is inserted between the heads to prevent them from touching.
a.
Never open the cartridge guide access without first unloading the heads from the load bail (Section
2.4.3).
b.
Insure the up stop is in proper adjustment so the diskette will clear the heads when it is inserted
(Section 4.6.2).
c.
Make sure the door lock is functioning properly so as not to remove a diskette while the heads are
loaded.
d.
The Read/Write heads are factory aligned with a four track offset. Loosening the head mounting
screw will destroy the alignment and the actuator assembly will have to be returned to the factory
for alignment.
2.4.0 REMOVALS, ADJUSTMENTS
NOTE: Read the entire procedure before attempting a removal and/or adjustment.
2.4.1 MOTOR DRIVE
2.4.1.1 DRIVE MOTOR ASSEMBLY: REMOVAL AND INSTALLATION
a.
Extract 3 contacts to disconnect motor from AC connector (J4).
b.
Loosen two screws holding capacitor clamp to the base. Remove rubber boot and disconnect
motor leads from capacitor.
c.
Remove connectors from PCB and remove PCB.
d.
Remove belt from drive pulley.
e.
Remove 4 screws holding the motor to the base casting and remove motor.
2.4.1.2 MOTOR DRIVE PULLEY
a.
Remove connectors from PCB and remove PCB.
b.
Remove belt from drive pulley.
c.
Loosen set screw and remove pulley.
d.
Reverse procedure for installation.
NOTE: When installing a new pulley, the drive pulley must be aligned with the spindle pulley so that the belt
tracks correctly.
2.4.2 HEAD COVER SHIELD REMOVAL
a.
Loosen the two screws holding cover to the guide opening assembly.
b.
Slide cover back toward drive and remove the cover.
2-6
2.4.3 CARTRIDGE GUIDE ACCESS
a.
Remove head cover shield (Section 2.4.2).
b.
Position head to approximately track 00 by turning the actuator shaft.
c.
Open cartridge guide by pressing pushbar on front of drive.
d.
Insert a clean piece of lens tissue between the heads to prevent them from touching each other
and gently lower the moveable head arm assembly.
e.
Loosen the two screws holding the cartridge to door latch plate.
CAUTION: Insure the head load arm is off the load bail first.
f.
Release safety catch on guide open assembly by pressing it towards the back of the drive.
g.
Swing cartridge guide out.
h.
To restore the cartridge guide to its normal position reverse the procedure and adjust per Section
2.4.9.2.
2.4.4 SECTORIINDEX LED ASSEMBLY: REMOVAL AND INSTALLATION
a.
Disconnect the wires to LED terminals (solder jOints).
b.
Remove the screw holding the LED assembly to the cartridge guide.
c.
Reverse the procedure for installation.
d.
Check index timing and readjust if necessary. Refer to Section 2.4.7.2.
2.4.5 WRITE PROTECT DETECTOR
2.4.5.1 WRITE PROTECT DETECTOR: REMOVAL AND INSTALLATION
a.
Remove connectors from PCB and remove. PCB.
b.
Extract wires from P2 connector, pins 4, D, 11, and M.
c.
Remove cable clamps.
d.
Remove head cover shield (Section 2.4.2).
e.
Remove screw holding the detector bracket and remove assembly.
f.
Reverse procedure for reinstalling. Connect the wires to P2 by the following: Red to (4), Black to
(D), White to (11), and Gray to (M).
2.4.5.2 WRITE PROTECT DETECTOR ADJUSTMENT
a.
Insert a diskette into drive. Write protect notch or hole must be open.
b.
Set oscilloscope to AUTO sweep, 2V/div. and monitor TP25.
c.
Loosen screw on detector assembly and adjust until maximum amplitude is achieved. Tighten
screw. Be sure the detector assembly is not to far forward as to restrict the diskette when it is inserted.
2-7
2.4.6 HEAD LOAD MECHANISM ASSEMBLY
2.4.6.1 HEAD LOAD MECHANISM: REMOVAL AND INSTALLATION
a.
Install a diskette.
b.
Remove head cover shield (section 2.4.2).
c.
Extract wires from P2 connector pins 17 and U.
d.
Unfaston the four mounting screws and remove the actuator assembly.
e.
To install, reverse the above procedure. Reference section 2.4.6.2 to adjust.
2.4.6.2 HEAD LOAD MECHANISM ADJUSTMENT
a.
Apply power to the drive and insert a double-sided diskette (SA 150). Step to track 00 and select
side 1 head.
b.
Select the drive and insure the head is loading. With the head loaded a clearance of .008" +
.005" - .000" should be obtained between the bail on the head load solenoid and the lift tab on the
head arm (see Figure 36). To adjust this clearance turn the screw located on top of the armature
(see Figure 36). Clockwise will decrease the clearance and counter-clockwise will increase the
clearance.
Load the head a couple of times and reverify the .020" clearance required.
c.
Step to track 76 and load the head, check the clearance between the bail and the lift tab. Lift tab
must not be in contact with the bail, and clearance must be a minimum of .020" and no greater
than .033".
d.
Return to track 00.
(1) Sync oscilloscope on TP 11 (+ Head Load). Set time base to 10 msec/division. Connect one
probe to TP1 and the other to TP2. Ground the probes on TP5. Set the inputs to AC couple,
add and invert one input. Set the vertical deflection to 200 mv/division.
(2) Select the side 1 head, energize the head load solenoid and observe the read signal on the
oscilloscope. The read signal should begin between 35 and 45 msec (see Figure 37).
(3) If the read signal begins sooner than 35 msec loosen screw holding the loader spring adjustment plate. Slide plate towards the solenoid body (see Figure 36). If the read Signal begins after
50 msec, slide the plate away from the solenoid body.
* When energizing the head load solenoid do not exceed one per second.
e.
A properly adjusted head load mechanism should load between 35 and 45 msec and the read
signal should settle out in 50 msec.
2-8
BAIL AND LIFT TAB
CLEARANC~
.020 " ± .012 "
FIGURE 36. HEAD LOAD MECHANISM ADJUSTMENT
FIGURE 37. HEAD LOAD TIMING
2-9
2.4.7 INDEX/SECTOR PHOTO TRANSISTOR ASSEMBLY
2.4.7.1 INDEX/SECTOR PHOTO TRANSISTOR ASSEMBLY: REMOVAL AND INSTALLATION
a.
Disconnect P2 connector from PCB.
b.
Remove wires from Door Closed switch ORG Common, Grey N/C, and Red N/O. Extract wires from
P2 connector Pins 12 BLK, N GREEN, P BRN, 6 ORG, F GRAY, and H RED.
c.
Remove the cable clamp holding wires for detector.
d.
Remove screw holding detector to the base plate and remove assembly.
e.
To install reverse procedure.
2.4.7.2 INDEX/SECTOR ADJUSTMENT
a.
Insert Alignment Diskette (SA 122).
b.
Step carriage to track 01.
c.
Sync oscilloscope, external negative, on TP12 (-Index). Set time base to 50",sec/division.
d.
Connect one probe TP1 and the other to TP2. Ground probes to the PCB. Set the inputs to AC. Add
and invert one channel. Set vertical deflection to 500MV/division.
e.
Observe the timing between the start of the sweep and the first data pulse. This should be 200 ±
100",sec. If the timing is not within tolerance, continue on with the adjustment.
f.
Loosen the holding screw in the Index Transducer until the transducer is just able to be moved.
g.
Observing the timing, adjust the transducer until the timing is 200 ± 100",sec. Insure that the
transducer assembly is against the registration surface on the base casting.
h.
Tighten the holding screw.
i.
Recheck the timing.
j.
Seek to track 76 and reverify that the timing is 200 ± 100j.tsec.
2.4.8 SPINDLE ASSEMBLY
a.
Remove head cover shield (Section 2.4.2).
b.
Switch out cartridge guide (Section 2.4.3).
c.
Remove drive belt.
d.
Remove the nut and 2 spring washers holding the spindle pulley. The Spanner Wrench 50752 must
be used to hold spindle.
CAUTION: The pre-loaded rear bearing may fly out when spindle pulley is removed.
e.
Withdraw spindle hub from opposite side of baseplate.
f.
Reverse the procedure for installation.
g.
Tighten nut to 20 in.llbs., insuring that the spring washers are compressed. Add a drop of LOCTITE
1/290 to the threads.
2-10
2.4.8.1 CLAMP HUB REMOVAL
a.
Remove hub clamp plate.
b.
Remove clamp hub and spring.
c.
To install, reverse the procedure. No adjustment necessary.
2.4.9 CARTRIDGE GUIDE
2.4.9.1 CARTRIDGE GUIDE REMOVAL
a.
Perform steps, 2.4.3, 2.4.4, 2.4.5 and 2.4.6.1.
b.
Loosen cartridge guide stop.
c.
Remove E-ring from pivot shaft.
d.
Remove pivot shaft.
e.
Tilt the cartridge guide slightly, and remove it from the upper pivot.
f.
To install the cartridge guide, reverse the procedure.
g.
Perform steps 2.4.5.2 and 2.4.5.2.
2.4.9.2 CARTRIDGE GUIDE ADJUSTMENT
a.
Insert the shoulder screw (tool PIN 50377-1) through the adjustment hole in the cartridge guide and
screw completely into the base casting (hand tight).
b.
Move the handle into the latched position and hold lightly against the latch.
c.
Tighten two screws holding the cartridge guide to the latch plate.
d.
Remove the tool and check to determine if the flange on the clamp hub clears the cartridge guide
when the spindle is rotating. If the clamp hub rubs on the cartridge guide, repeat the adjustment
procedure.
e.
Adjust the cartridge guide stop so that it is within .005 inch of the base casting.
f.
Check index alignment (Sector 2.4.7.2).
g.
Insert diskette, close and open door, then check for proper operation.
i:"-.
2-11
2.4.10 HEAD AMPLITUDE CHECK
These checks are only valid when writing and reading back as described below. If the amplitude is below the
minimum specified, before re-writing and re-checking, insure that the diskette is not "worn" or otherwise
shows evidence of damage on either side. Insure head load down stop is properly adjusted (Section 2.4.6.2).
a.
Install good media.
b.
Select the drive and step to TK 76.
c.
Sync the oscilloscope on TP12 (-Index) for single sided diskettes, TP13 for double sided diskettes,
connect one probe on TP2 and one on TP1 , on the drive PCB. Ground the probes to the PCB and
invert one input. Set volts per division to 50mv and time base to 20 Msec per division.
d.
Write the entire track with 2F signal (all one's).
e.
The average minimum read back amplitude peak to peak, should be 130 millivolts for side 0 and
130 millivolts for side 1.
If the output is below minimum and different media is tried and the output is still low, it will be necessary to
install a new head and actuator assembly.
2.4.10.1 HEAD ACTUATOR ASSEMBLY: REMOVAL AND INSTALLATION
a.
Remove the connectors and the PCB.
b.
Remove cable clamp holding R/W head cable on PCB side of drive.
c.
Remove the grommet from the cable bracket on head side.
d.
Unload heads (Refer to Section 2.4.3, Steps 0 & E).
e.
Remove the two or four screws holding actuator assembly to the base casting.
f.
Carefully remove heads and actuator assembly from the drive. Take care as not to snag the heads,
load arms, or read/write head cable on the casting.
g.
To install, procede as follows:
(1) Hold assembly at a slight angle towards you when installing (approximately 15°CCW viewed
from rear).
(2) Rotate actuator into position against the ledge while simultaneously lifting the arm tab with the
bail so that the heads are separated and the protective paper between them falls free.
(3) Position the actuator casting firmly and squarely against the ledge on the base casting and
secure with two or four screws and washers (install the locating screw nearest the ledge first).
2-12
2.4.10.2 HEAD PENETRATION ADJUSTMENT
a.
The tools necessary to perform this alignment procedure will consist of penetration gauge tool set ,
screwdriver and '/4" nut driver (see Figure 38).
......~------TOOL
MASTER
..........- - - - - - - - - - - - - - D I A L INDICATOR
..........------PLATE
$.M%:c;.;""Jfu: .....-------SCREWDRIVER
......-------NUT DRIVER
FIGURE 38. HEAD PENETRATION TOOLS
2-13
b.
Set up the penetration dial indicator on the penetration tool master. Check penetration tool to make
sure it's indicating surfaces are clean and properly set; (long hand on zero and small hand on
three) while it's resting on the penetration tool master. See Figure 39.
NOTE: When the tool is not being used , it should be kept where it won 't be dropped or knocked off
the work bench.
FIGURE 39.DIAL INDICATOR
2-14
c.
With the drive in the horiztonal position, remove HAC shield and door open, slide the penetration
plate into the drive with the tappered end in first and counte r bore side up. Slide the plate up and
over the spindle until it's squarely over the spind le and close the door. See Figure 40.
NOTE: The penetration plate is made of harden tool ste el and care should be used not to damage
spindle or any other part of the drive during insertion of extraction.
FIGURE 40. PENETRATION PLATE INSTALLATION
2-15
d.
Next install the indicator block into the penetration plate until you feel the block snap into place.
See Figure 41 .
NOTE: Make sure all surfaces are clean, the block is squarely and fully snapped onto the plate.
Also avoid handling the block by the indicator.
FIGURE 41. DIAL INDICATOR INSTALLATION
2-16
e
The shaft that extends from the stepper motor can be used to move the head up far enough so th e
gauge point is indicating off the tab, on the si de zero head as shown in Figure 42.
r.
Check the di al indicator for the proper setting. The long hand should be between + 3 and -3 with
the short hand pointing at three. If penetration se tting is out of thi s rang e th en continue with procedure starti ng at step g. See Figure 43 .
GAUGE POINT
INDICATION TAB
FIGURE 42. INSTALLATION CHECK
FIGURE 43. CORRECT PENETRATION
2-17
,
FIGURE 44. PENETRATION ADJUSTMENT
g.
With the penetration gauge installed set the drive up in the vertical position , the AC motor should
be closest to the bench.
h.
Loosen the two or four mounting screws using a 1/4" nut driver.
i.
Adjust HAC assembly left to right until the reading on the penetration gauge reads; small hand on
three and long hand on zero ± .003.
A. If small hand is on the left side of three, the HAC assembly must go to the right.
B. If smal l hand is on the right side of three, the HAC assembly must go to the left.
.
When penetration is set tighten the two or four mounting screws using a 1/4" nut driv9r .
k.
As you tighten the two mounting screws, make sure the HAC casting is flush (making contact) with
the machined lip on the base casting .
I.
Check penetration gauge again to insure proper alignment . If not return to procedure step g.
m.
Remove the indicator block (remember to handle with care) . Open the door and remove the
penetration gauge .
n.
Replace the HAC shield.
J.
2-18
2.4.10.3 HEAD RADIAL ALIGNMENT
NOTE: The actuator assembly is aligned at the factory and adjustment is not normally required after replacing a head and actuator assembly. If after checking and the lobes are within 70% of each other,
alignment is not recommended.
a.
Insert Alignment Diskette (SA122).
NOTE: Alignment diskette should be at room conditions for at least 1 hour before alignment checks.
b.
Steps the heads to track 38.
c.
Sync the oscilloscope, external negative, on TP12 (-Index). Set the time base to 20Msec per division. This will display over one revolution.
d.
Connect one probe to TP1 and the other to TP2. Ground the probes to the PCB. Set the inputs to
AC, Add and invert one channel. Set the vertical deflection to 100MV/division.
e.
The amplitude of the two lobes must be within 70% of each other. If the lobes do not fall within this
specification continue on with the procedure (Refer to Figure 45).
f.
Loosen the two or four mounting screws, which hold the motor plate to the support bracket (Refer
to Figure 46).
g.
Move the plate, by rotating the eccentric adjusting nut.
h.
When the lobes are of an equal amplitude, tighten the motor plate mounting screws (Refer to
Figure 46).
i.
Check the adjustment by stepping off track and returning. Check in both directions and readjust as
required.
j.
Whenever the Head Radial Alignment has been adjusted the Track 00 detector adjustment must be
checked. (Section 2.4.11 .2).
2.4.10.4 READIWRITE HEADS AZIMUTH CHECK
The azimuth is not field adjustable. If, after performing this check the waveform on the oscilloscope is not
within ± 18' replace the Head Actuator Assembly.
a.
Install Alignment Diskette SA122. Select the drive and step to track 76.
b.
Sync the scope external negative on TP12, set time base to .5 MSec per division.
c.
Connect one probe to TP1 and the other to TP2. Invert one channel and ground the probes to TP5
& 6. Set the inputs to AC, ADD, and 50 MV per division.
d.
Compare waveform to Figure 47. If not within the range shown replace the Head Actuator
Assembly 2.4.10.1
2-19
EVEN AMPLITUDE (100%), ON TRACK
LEFT 80% OF RIGHT,
+ 1 MIL OFF TRACK TOWARD TK 0
LEFT 60% OF RIGHT,
+2
LEFT 40% OF RIGHT,
+ 3 MIL OFF TRACK TOWARD TK
MIL OFF TRACK TOWARD TK 0
0
RIGHT 80% OF LEFT, -1 MIL OFF TRACK TOWARD 76
RIGHT 60% OF LEFT, -2 MIL OFF TRACK TOWARD 76
RIGHT 40% OF LEFT, -3 MIL OFF TRACK TOWARD 76
FIGURE 45. HEAD RADIAL ALIGNMENT
1-"'.
o
.,.
000
®
FIGURE
46. MOTOR PLATE
,
2.4.11 DOOR LOCK SOLENOID AND IN USE LED ASSEMBLY REMOVAL
a.
Perform steps 2.4.12a and 2.4.12h.
b.
Remove door lock assembly
c.
Reverse procedure to install new assembly.
d.
Adjust of the door lock should not be necessary. If it has to be, the gap between the armature tab
and the latch should be .015 ± .010. This adjustment can be made by loosening the two screws on
the armature.
2·20
0'
+18'
+12'
-18'
-12'
FIGURE 47. AZIMUTH BURST PATIERNS
2-21
.2~4.12TRACK 00 DETECTOR: REMOVAL AND INSTALLATION
a.
Remove head cover shield (Section 2.4.2).
b.
Swing cartridge guide open (Section 2.4.3).
c.
Manually rotate stepper shaft and move carriage to track 77.
d.
Remove screw holding bracket to base casting and remove bracket and detector.
e.
Remove PCB connector and remove PCB.
f.
Extract cable from P2 connector; Pin 3 BRN, C BLACK, 10 ORANGE, and L RED.
g.
Remove cable clamps and remove Detector assembly.
h.
To install, reverse the procedure.
i.
Adjust according to Section 2.4.11.2.
2.4.12.1 TRACK 00176 STOP ADJUSTMENT
-
a.
"
Not field adjustable.
2.4.12.2 TRACK 00 DETECTOR ASSEMBLY ADJUSTMENT
a.
Check head radial alignment and adjust if necessary before making this adjustment.
b.
Insert diskette.
c.
Connect oscilloscope to TP26. Set vertical deflection of 1vldivision and sweep to continuous.
d.
Step carriage to track 02. TP26 should go low. Adjust the detector assembly towards the actuator
assembly if not low.
e.
Check the adjustment by stepping the heads between tracks 00 and 02, observing that TP26 is low
at track 02 and high at track 00. A perfect adjustment is if you have a square wave on a scope.
2.4.13' FRONT PLATE ASSEMBLY REMOVAL
a.
Insert the cartridge guide adjustment tool (PIN 50377-1) through the adjustment hole in the cartridge guide and screw completely into the base hold casting (hand tight).
b.
Remove the door lock wires from P2, Pin 2-black, B-brown, 9-violet and K,blue.
c.
Remove the cable clamp holding the door lock wires.
d.
Remove the two allen head screws holding the handle to the front plate and remove the handle.
e.
Remove the four screws holding the front plate to the base casting.
f.
Remove two screws holding door lock assembly to the front plate.
g.
Remove two allen head screws holding the In Use LED to the door lock assembly.
h.
Grasp both ends of the push button and bow outwards to remove LED.
i.
Reverse procedure to install.
j.
Check Index adjustment (Section 2.4.7.2).
, 2-22
SECTION III
FLOW CHARTS
The following flowcharts are furnished as an aid to malfunction analysis.
Write Protect Inoperative
Head Load Inoperative
Track 00 Indicator Inoperative
Drive Not Coming on Line
Diskette Not Rotating
Index Pulse Not Operative
3-2
3-3
3-4
3-5
3-6
3-7
3-1
WRITE PROTECT INOPERATIVE
START.
Insert Diskette
with Write
Protect Slot
Uncovered
Perform
Write Protect
Assembly Adj.
Para. 2.4.5.2
YES
Insert Diskette
with Write
Protect Slot
Covered
END
NO
Replace
Write Protect
Assembly
Para. 2.4.5.1
YES
Replace
Drive
PCB
3-2
HEAD LOAD INOPERATIVE
Check
Logic Level
at 5C Pin 3
NO
Check
Logic Level
at TP11
END
Check
110 Cable or
Controller
Check Door
Close Switch
for Loose Wire
and Insure Closure
Check
Logic Level
at 3A Pin 3
Replace
Door Switch
NO
Replace Head
Load Solenoid
Para. 2.4.6
END
NO
END
Replace
Drive
PCB
3-3
TRACK 00 INDICATOR INOPERATIVE
Move Track 00
Flag Towards
Track 76
Replace
Track 00
Assembly
Para. 2.4.1.22
Check Logic
Level at
TP26
Low
Replace
Drive
PCB
Return
Track 00 Flag
to its Rest
Position at
Track 00 Stop
Step to
Track 02
Check Logic
Level TP26
Perform Track 00
Assembly Adj.
Para. 2.4.12.2
YES
Step to
Track 00
Check Logic
Level TP26
NO
3-4
DRIVE NOT COMING ON LINE
START
Check
Board for
DC Voltage
Check
Terminator
5E (1500hm)
Check
Power
Source
Check
Drive
Select
Jumper
Install
Terminator
Install
Jumper
END
Install
Jumpers
Check
I/O Cable or
Controller
Replace
I/O Cable
& Controller
Replace
Drive
PCB
3-5
DISKETTE NOT ROTATING
Check AC
Voltage at
Drive Motor
Connector J4
Check
AC Power
Source
Check
Drive Motor
for Rotation
Replace AC
Drive Motor
Para. 2.4.1
Check
Drive
Belt
Replace
Drive
Belt
Check Cartridge
Guide Adjustment
Para. 2.4.9.2
END
3-6
END
INDEX PULSE INOPERATIVE
Check to
See if Diskette
Is Properly
Installed
Turn Diskette
Over Re·insert
Check
Diskette
Rotation
Check
AC Power
Source and
Connector at J4
END
Check TP13
for Pulse
167.66 Msec
Replace
Index/Sector
Phototransistor
Assembly Para.
2.4.7
END
Replace AC
Drive Motor
Para. 2.4.1
END
Check TPI
for Pulse
167.66 Msec
Perform
Index/Sector
Adjustment
Para. 2.4.7.2
Replace
Drive
PCB
3-7
SECTION IV
LOGIC DIAGRAMS
The following diagrams are furnished as an aid for tracing signal flow.
4-1
..s:12 - - - - - - 0IW,.=,--_
_ _ _ _ _ _ _ _ _...,.JoI..,.,.... + 5
L IWG
-IWR/STEP.
V-.
~
RIW
HEAD
1
+ WRITE PROTECT - ' - - - - - - - - - - - - - - ' ; 1
+5V ---;::o'M,.,
-WRITE GATE
-SEP DATA
-READY 1 ....:.----.,......,,_.../
-SIDE
+5V1
:::~~~::~--------------------~--------~
-SEP CLOCK
-WRITE DATA
-READ DATA
-READ GATE
+ DRIVE SELECT INT 1
-SIDE 1
-DIRECTION SELECT - - - - - - - - ,
+ 5V -----'WIr""""
K
2
-DRIVE SEL 1 ~~-----t-~
B
30
+ IN USE
32
~
4B
+5V-----~~-------"
18
-HEAD
L~:: -sv---~-. ~-J-....
-IN USE
C
----IO
U
CH}-I-------t-~r:~-:~=~==========+:5:V:-::~~\r_"1
IjlD
DC
TWO PULSE
DETECTOR
-POWER ON RESET - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -.....
·DRIVE SEL INT
2
GND (IN USE)
·HEAD LOAD
+ DRIVE SEL INT
.:s:q----------.. . .
16
-DOOR LOCK
):)----10
P---t--j----tlL..,..I
12
m ..
O-----------y-
DISK CHANGE
(OPTIONAL OUTPUT)
·DOOR CLOSED
10S"i"Z-
I-------------------y-
·TWO SIDED
(OPTIONAL OUTPUT)
RR
22
I
·READY
DOOR CLOSED
+~~~~RON
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ____
RI
R
20
·INDEX
+ INDEX
tINDEX/SECTOR 0
INDEX
LOCKOUT/
SELECTOR
+ INDEX SECTOR 1
+ 2 SiDED
f-----~~-+5V
24
·SECTOR
·INDEX 0
+ 24V
+ STEPPER ENABLE
+ STPR RES A
+STPR WNDG A
STEP CNTR
\ -_ _ _ _ _ _~ D
.-----~ C
+ STPR WNDG B
Q
Q ~-+--.
16
~--+_---__JD
DIRECTION SELECT
(-; FWD + ; REV)
r.---.-----W
Q ~-+--+---I
+ STPR RES B
----~~~r--.J
C
Q~+-+---..L-__~--,
- - - - J . . 1-----.---.....---1
-DIRECTION SEL _ _ _ _ _ _ _ _ _.J
-STEP
-READ GATE
-DRV SEL INT
L
2
-TRK 00
-TRACK 00
~
W
-POWER ON RESET
DRVR
+ WRITE
+ DRIVE SEL )NT - - - - - - -
M
44
-WRITE PROTECT
PROTECT
P5
+ 24V
+ WRITE PROTECT
J5
< <
~-.------- + 24V
DC
2.3.6
+ 5V
+ 24V ~
TP 28
+ 24V ~ + 24VIHEAD LOAD)
<
DCGND
D
~--.JOIN"v---+---'::...J,;21
2
10
+ 5V ITRK
ill
+ IN D EX LE D
GND IINDEX)
00)
C
+ 5V
+ WRITE PROT LED
GND IWRITE PROT)
11
+ 5V IWR PROT)
+ 24V IDOOR LOCK)
17
+5V--'--~~r----~
<
DC
9
TP5
TP6
TP7
12
'----"I.M.--+---l,.2
+ TRK 00 LED
c
GND ITRK 00)
2
GND TO DOOR
CLOSED SW
IINDEX)
SIGNALGND
NOTES:
ill CONNECTOR SYMBOL REFERENCE 1 ;
m
Jl. 2 ;
J2. 5 ;
J5.
ALL ODD NUMBERED PINS ON Jl CONNECTOR ARE GROUND.
P4
(1
mMOTOR POWER A
J4
[IjMOTOR POWER B
I
(GRN YEL)
I
(BLK YEL)
(3
S
BLK
3
DRIVE
MOTOR
J,
RED
BLU
OB
4
OC
T
RED
00
~
BLK
I
(2~1
I
m FRAME GROUND
OA
(BLK)
W
DJHEAD LOAD
I
+ 24V (TO
YEL
U
~
(BLK)
W
SOLENOID)
STEPPER
MOTOR
WHT
17
0
HEAD
LOAD
SOLENOID
(WHT)
-------tl
6
GND TO DOOR _ _ __lo.S'27f----------(:....-O-R-G:....-)
-V
CLOSED SW
DOOR
: CLOSr SW
I~---(-RE-D.....:.)--H-lo.~221-_(GRY)
F
W
OJ
DOOR
LOCK---_-_-~~~:~22
+ 24V (TO SOLENOID)
(BLU)
:
W
NOTES:
GND WHEN ACTIVE AND
[g] 115 OR 230 VAC.
OJ
(VIOLET)
+ 24 WHEN INACTIVE.
DDOOR
LOCK
SOLENOID
-DOOR CLOSED
+ DOOR CLOSED
INDEX/SECTOR 0
(YEl)
+ INDEX LED
LED
INDEX/SECTOR 1
(BRN)
(ORG)
GND (INDEX)
+ TRK 00 LED
GND (TRK 00)
.l>I
(]'I
+ WRITE PROT LED
GND (WRITE PROT)
GNO (IN USE)
OJ IN USE LED
==:c
2
~
=:
=:2
D
4
B
NOTES:
GND WHEN INACTIVE AND
OJ
LED
DET
(BLK)
N 2
+ INDEX/SECTOR 0
P 2
+ INDEX/SECTOR
12
2
1
+ 5V (INDEX)
TRACK 00
(BLK)
(RED)
lLE+ETI
(BRN)
(ORG)
WRITE PROTECT
(BLK)
(RED)
ILEO]OETI
(BRN)
(BRN)
IN USE
8
(BLK)
+ 1.5VDC WHEN
ACTIVE.
(ORG)
L:
10 2
1::
-TRK 00
+ 5V (TRK 00)
+ WRITE
+ 5V (WR
PROTECT
PROT)
SECTION V
PHYSICAL LOCATIONS
5-1
P2 CONNECTOR
DOOR L
K
SOLENOID
CARTRIDGE GUIDE
ADJUSTMENT
SCRE
INDEX/SECTOR
LED
CARTRIDGE GUIDE
ADJUSTMENT TOOL
HOLE
HUB CLAMP
PLATE
HEAD LOAD
MECHANISM
SECTION VI
ILLUSTRATED PARTS CATALOG
6-1
."
C5
,
(j)
F\)
c:
::D
m
.1::0
90
- t.
0
~
10
'T1
c;
C
::D
m
0'>
I
W
-~
I\:l
0
~
FIGURE
& REF
NUMBER
48-1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
46
47
PART
NUMBER
11305
50747
50748
15004
50746
50744
50745
12028
10013
15669
12015
11904
50358
50357
51127
51056
12013
51027
12053
51063
51134
50167
50670
50168
51198
10801
17200
50559
12013
12032
11905
50142
12011
12053
51058
51028
12026
50166
50018
10800
50019
51046
12026
12036
50016
12509
10025
50356
50355
10426
ary
PER
ASM
DESCRIPTION
DRIVE ASSEMBLY SA850/851
CLIP (RETAINING RING)
MOTOR ASSEMBLY, 115V, 50/60 HZ
MOTOR ASSEMBLY, 230V, 50/60 HZ
CAPACITOR
BRACKET
MOTOR 115V, 50/60 HZ
MOTOR 230V, 50/60 HZ
SCREW HEX HEAD 8-32 X .75
WASHER
HOUSING, 3 PIN CONNECTOR
SCREW, 8-32 X .312
SCREW, SET 6-32 X .125
PULLEY, 60 HZ
PULLEY 50 HZ
HEAD ACTUATOR ASSEMBLY
BRACKET. TRACK OC
SCREW, 6-32 X .312
TRACK 00 ASSEMBLY
SCREW
GUIDE OPEN ASSEMBLY
CARTRIDGE GUIDE ASSEMBLY (SEE FIGURE 50)
PIVOT
PIVOT (RACK MOUNT)
BIAS SPRING
SPINDLE
FLANGED BEARING, SPINDLE
DOOR OPEN SWITCH
DEFLECTOR
SCREW 6-32 X .438
SCREW #8 X .50 2
FRONT PLATE ASSEMBLY (SEE FIGURE 51)
SCREW
HANDLE
SCREW, HEX HD 4-40
SCREW
COVER
RESISTOR ASM
SCREW
SPRING, SPINDLE
SPACER, SPINDLE LONG
BALL BEARING
SPACER SPINDLE SHORT
PHOTO XSTR ASM
SCREW
SCREW
PULLEY SPINDLE
WASHER, SPRING #8
NUT 8-32
BELT, 60 HZ
BELT, 50 HZ
CABLE CLAMP
6-4
1
1
1
1
1
1
1
4
4
1
2
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
2
4
2
2
1
4
2
1
1
2
1
1
1
1
1
2
1
1
2
1
1
1
1
FIGURE 49.
6-5
"
FIGURE
&REF
NUMBER
PART
NUMBER
49-1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
51134
50555
12015
50609
51062
12015
12020
50546
50254
50031
12016
51029
50151
10187
12015
51061
50313
12026
51176
51075
10014
12020
aTY
PER
ASM
DESCRIPTION
CARTRIDGE GUIDE ASSEMLBY
SPRING, EJECTOR
SCREW, 8-32
EJECTOR ASSEMBLY
STRIPPER BOTTOM
SCREW, 8-32
SCREW, 8-32
PLATE, HUB CLAMP
HUB ASSEMBLY
SPRING, CLAMP
SCREW, 8-32
LED ASSEMBLY
LATCH
SCREW 6-32
SCREW 8-32
STRIPPER, TOP
WRITE PROTECT ASSEMBLY
SCREW
HEAD LOAD MECHANISM
LIMITER
#8 WASHER
SCREW 8-32
6-6
1
1
2
1
1
2
2
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
2
FIGURE 50."
6-7
FIGURE
& REF
NUMBER
50
-1
-2
-3
-4
-5
-6
-7
-8
PART
NUMBER
51037
51043
50587
50349
50667
51038
10002
12035
50691
12013
50183
QTY
PER
ASM
DESCRIPTION
FRONT PLATE ASSEMBLY LITE/LOCK
FRONT PLATE ASSEMBLY LITE/LOCK (RACK MOUNT)
PUSH BAR
FRONT PLATE
FRONT PLATE (RACK MOUNT)
LATCH ASSEMBLY, DOOR LOCK
SOLENOID
SCREW 4-40 X .250
SPRING LATCH INTERLOCK
SCREW 6-32 X .312
BUMPER
-
6-8
1
1
1
1
1
2
1
2
1
SECTION VII
SCHEMATIC DIAGRAMS
7-1
a
7
I
6
f
•
+
5
J
4
I
2
I
3
T
1
~'2.
~I50
SHIELD 0
o
R/wasl
CR2
_ _ _.>..:3 :>
....
..
CR.I
p-/v-I II
elf
-
: (/.5EO ON ASSEMBI-Y +5>lio/
:,
I
25'202 - 3
12.78,
R/W 12
~IDE
:
I CT
3B
3
~
~4~
ERASt
¢
RIB
____________________~~~~------__1~+-~
Ii
S\1IELDI~
.i.
8~ \I
120
I tl
S Q.7'2
(>
MPS'l22ZA. _
Ol>.,A
- MEDI"
,.... R"''''t>''
" .,
-DR\! 'SCL I"II
J
+ \NRIIE. ~o-n:.c:r
~ ~,
..
I~~K.>liS""
c O2
CI,-\NLL
{5)0 [;
.L
-=
B
5E
sr.:::;~-\l°1-5'11
12.;5
II-
13
L .•
<>1.51<.
L.!..!..!.I
~rl~I~------~
WF'-
~ K'1>t=~
@~T
~
'2L....!.J
Q~
~f-1""-'7F_
RQ 7
4
5%
2
l
6D
:I
8.21::.
I
:
,
L ---------- ---
- -'
I
I
I
10"/0
RZb
~
121< ;:-
I
,,
I
z.&-iPII
I
I
,
~t>£-.-:-...
,_
I
1
7E b'~__- - - 4 . .. J~
90jr'--'"
",,:-::e:e:=",\;
):p"
..'(>++-_7~
I
5 ....J-,_...::'50~E- - FM <;:,EP eLK
'----'
~
.§.l6F p..:::
-zr
':
J
--
I
I
~O.I
I
I
I
I
I
,
I
5J
W~y~~-----------------------~
4.
I
~>,I-,-I___!~ CE" ~FJP."3.:::-,-:__48=)1:-
I
,I
,
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