Teledyne Ax300 I Users Manual M75708 0

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Portable Oxygen Analyzer

OPERATING & SERVICE INSTRUCTIONS FOR

AX300-I
PORTABLE OXYGEN ANALYZER

P/N M75708
REV 0
ECO # 03-0038
0086

TYPE B EQUIPMENT:

Equipment providing a particular degree
of protection against electric shock,
particularly regarding—
• Allowable LEAKAGE CURRENT
• Reliability of the protective earth
connection (if present).

Teledyne Analytical Instruments

AX300-I
Copyright © 2002 Teledyne Analytical Instruments
All Rights Reserved
No part of this manual may be reproduced, transmitted, transcribed, stored in a
retrieval system, or translated into any other language or computer language in whole
or in part, in any form or by any means, whether it be electronic, mechanical, optical,
manual, or otherwise, without prior written consent of Teledyne Instruments,
Analytical Instruments, 16830 Chestnut Street, City of Industry, CA 91749-1580

FCC Statement
This equipment generates and uses radio frequency energy, and if not installed and
used in strict accordance with the manufacturer's instruction manual, may cause
interference to radio and TV communications. It has been type-tested and certified to
comply with the limits for a Class A, and exceeds limits for a Class B, computing
device pursuant to Subpart J of FCC Rules, which are designed to provide reasonable
protection against such interference when installed in a commercial and residential
environment. Operation of this equipment in a residential area may cause interference,
in which case the user, at his own expense, will be required to take whatever measures
may be required to correct the interference.

Note: The above statement is required by the FCC for any device
that incorporates microprocessors.
Warranty
Teledyne warrants that the goods are free from defects of material and of construction
for a period of 2 years from the date of shipment from Teledyne. The Class R-17MED
Micro-Fuel Cell is warranted for two years from the date of shipment from Teledyne.
The liability of Teledyne if any, shall be limited solely to the replacement and repair of
the goods and shall not include shipping costs or other incidental damages as defined in
Section 2-715 of the U.S. Uniform Commercial Code.
This warranty is null and void if any goods are subjected to misuse, negligence,
accident, or repairs other than those performed by Teledyne or an authorized service
center.

CAUTION:

FEDERAL LAW RESTRICTS THIS DEVICE TO SALE
BY OR ON THE ORDER OF A PHYSICIAN.

Teledyne Analytical Instruments

Portable Oxygen Analyzer

About This Manual
The AX300-I Operator's Manual provides both introductory and
detailed information for configuring and operating these instruments.
The manual takes you from the time you unpack the instrument until you
complete the first gas analysis. The bulk of the manual contains
operating procedures and information. There are also cautions,
warnings, and guidelines to ensure that your analyzer operates normally
and to its full potential. A troubleshooting section is available to assist
you with common problems and a complete product specifications and
spare parts list is included as an appendix.
•

Chapter 1:

An introduction to the analyzer and its
components, features and applications.

•

Chapter 2:

Step-by-step set-up procedures and
information.

•

Chapter 3:

A guide for daily operational maintenance and
troubleshooting.

•

Appendix:

Specifications and available spare part options
for the analyzer, and detailed application
considerations to aid in troubleshooting, etc.

How To Use This Manual
This manual is designed to walk you through the initial set-up of
the AX300 Portable Oxygen Analyzer. After you have used it to initially
install your analyzer, it becomes a quick reference guide to help you
with specific questions or operating problems.
Before you turning on the instrument, you are advised to read the
safety information on the next few pages and the information found in
Chapters 1 and 2. These chapters acquaint the user with the instruments
use and operation before placing it into operation.

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AX300-I

Safety Messages
Your safety and the safety of others are very important. Please
carefully read the following safety messages.
Safety message are indented to alert the user of potential hazards.
Each safety message is associated with a safety alert symbol. These
symbols are found in the manual and on the instrument. The definition
of these symbols is described below:
CAUTION: Refer to the instructions for details on the
specific danger. These caution symbols warn of specific
procedures, which if not followed could cause bodily Injury,
and/or damage the instrument.
WARNING: This symbol is use to alert the operator of a
condition that could cause bodily harm.
NOTE: Additional information and comments regarding a
specific component or procedure are highlighted in the form
of a note.
CAUTION:

THE ANALYZER SHOULD ONLY BE USED FOR THE
PURPOSE AND IN THE MANNER DESCRIBED IN
THIS MANUAL.
IF YOU USE THE ANALYZER IN A MANNER OTHER
THAN THAT FOR WHICH IT WAS INTENDED,
UNPREDICTABLE BEHAVIOR COULD RESULT
POSSIBLY ACCOMPANIED WITH HAZARDOUS
CONSEQUENCES.

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Table of Contents
Safety Messages .......................................................................... iv
List of Figures.............................................................................. vii
List of Tables .............................................................................. viii
Introduction ................................................................................... 9
1.1 Applicable Standards

1.2 Features

1.3 Options

1.4 Applications

1.5 Theory of Operation

1.5.1 Sensor

1.5.2 Signal Processing

Operation ..................................................................................... 14
2.1 Setup

2.1.1 Sensor Installation or Replacement

2.1.2 Mounting

2.1.2.1 V-Mount Adapter Installation

2.1.2.2 Universal Mounting Clamp Installation

2.1.3 Battery Installation

2.1.4 Calibration

2.1.5 Output 0-1 VDC or RS232

2.2 Use

2.2.1 Procedure

2.3 Gas Sampling

2.3.1 Humidity

2.3.2 Temperature

2.3.3 Pressure

2.3.4 Discrepancy in Readings

Teledyne Analytical Instruments

AX300-I
2.3.5 Anesthetic Gases

2.3.5.1 Gases That Induce Reading Error

2.3.5.2 Care After Use in Nitrous Oxide

2.3.6 Cleaning
2.4 Do’s and Don’ts

28
28

Service Manual ............................................................................ 31
3.1 General Service Information

3.2 Overall Maintenance

3.3 Battery Maintenance

3.4 Sensor Maintenance

3.5 Calibration

3.6 Gas Sampling

3.6.1 Humidity

3.6.2 Temperature

3.6.3 Pressure

3.6.4 Discrepancy in Readings

3.6.5 Anesthetic Gases

3.6.5.1 Gases That Induce Reading Error

3.6.5.2 Care After Use in Nitrous Oxide

3.7 Troubleshooting

3.8 Watchdog

3.9 Other Problems with the Instrument

3.10 Return Authorization for Service

Appendix...................................................................................... 41
A.1 Specifications

A.2 Spare Parts List

A.3 Optional Accessories

Index............................................................................................. 45

Teledyne Analytical Instruments

Portable Oxygen Analyzer

List of Figures
Figure 1-1: AX300 Front View ......................................................... 9
Figure 2-1: Installing the R17MED Sensor .................................... 15
Figure 2-2: Sensor Cable Connection to Analyzer ....................... 16
Figure 2-3: Mounting the Sensor in the Tee Adapter..................... 16
Figure 2-4: V-Mount Adapter Installation ....................................... 17
Figure 2-5: Brass Insert for Universal Mounting Clamp ................. 17
Figure 2-6: Installing Batteries....................................................... 18
Figure 2-8: 0-1 VDC or RS 232 Digital Output Port ....................... 21

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AX300-I

List of Tables
Table 2-1: Oxygen Reading Error in a Mixture of Anesthetic Gas. 27
Table 3-1: Oxygen Reading Error in a Mixture of Anesthetic Gas. 35
Table 3-2 Troubleshooting ............................................................ 36
Table 3-3 Error Codes................................................................... 39

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Portable Oxygen Analyzer

Introduction

Introduction
The Teledyne Analytical Instruments AX300-I Oxygen Analyzer
here after referred to as AX300-I is a portable instrument that provides
fast and accurate oxygen analysis. These instruments are designed to
analyzer up to 100% oxygen concentration in medical gas mixtures.
Because they are microprocessor-based, the AX300-I analyzers have a
unique combination of features that make them very easy to use. The
operator interface is accomplished through a series of buttons located
conveniently on the front face of the instrument. The AX300 is shown
in Figure 1-1.

Figure 1-1: AX300 Front View
The LCD display consists of up to 3.5 characters plus a decimal
point indicator capable of displaying up to 105%. (See Section 1.3
Options for alternate display configuration). An integral battery life
indicator is displayed continuously on the AX300-I.

Teledyne Analytical Instruments

Introduction

AX300-I

The instrument is powered by three AA alkaline batteries and is
designed to operate for 2000 hours in Non-alarm State.
Oxygen analysis is linear across the single range of 0-100% using
Teledyne’s class R17MED oxygen sensor. A unique sensor failure
alarm is incorporated which warns the user if the sensor signal is lost or
low. When this occurs, the √ SENSOR display flashes. The alarm buzzer
can be silenced by pressing the ALARM SILENCE key () or
pressing the unlock key.

1.1 Applicable Standards
The AX300-I is built to meet or exceed regulatory and industry
standards for use as a medical device. These instruments are designed,
built and tested with the following applicable standards:
ASTM F 1462: Specifications for Oxygen Analyzers
ASTM F 1463: Specifications for Alarm Signals
ISO 7767:

Oxygen Analyzers for Analyzing patient
Breathing Mixtures

ISO 9703-1:

Anesthesia and Respiratory Care Alarm Signals
Part 1

ISO 9703-2:

Anesthesia and Respiratory Care Alarm Signals
Part 2

EN/IEC 60601-1-2: Medical Electrical Equipment—Part 1 General
Requirements for Safety. Electromagnetic
Compatibility Requirements and Test
MIL-STD-810E: Environmental Test Methods
EN/IEC 60601-1: Medical Electrical Equipment-General
Requirements for Safety

1.2 Features
The AX300-I is a compact, versatile instrument capable of rapidly
measuring the oxygen content of an atmosphere or environment
accurately to ±2% over the range 0-100% oxygen. The following
features are standard on the AX300-I:
•

Large easy to read 3 1/2 digit LCD display (see options)

•

Automatic LCD back lighting upon key press

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Portable Oxygen Analyzer

Introduction

•

Microprocessor controlled

•

Sensor fail/disconnect alarm indicator (audible and visual)

•

Alarm silence button

•

2000 operating hours from 3 AA alkaline batteries

•

Battery status indicator

•

Stand for upright tabletop deployment

•

Hardware for pole clamping and V block support

•

Rugged high impact ABS construction

•

Splash resistant case.

•

Long life (36 months in air) class R17MED sensor

•

0-1 VDC digital output (optional RS-232)

•

FDA approved and cleared for CSA/CE marking

1.3 Options
The following instrument options are available for the AX 300-I
analyzer:
•

A-Option—3-digit LCD display instead of 3 1/2 digit

•

B-Option—RS 232 digital output instead of 0-1VDC

Note: Contact the factory for retrofitting an existing instrument for
3 digit LCD display. For RS-232 reconfiguration, see
Section 2.1.5.
In addition to the above instrument configuration options, the
following optional equipment is available for your instrument:
•

Universal Pole Mounting Clamp (P/N CP 2343)

•

V-Mount Pole Clamp (P/N CP 2344)

•

V-Mount Wall Adapter P/N B 647)

•

0-1 VDC Interface Cable (P/NB-75554)

•

RS 232 Interface Cable (P/N B-75555)

Teledyne Analytical Instruments

Introduction

AX300-I

1.4 Applications
The AX300-I analyzers is intended for spot checking concentration
of oxygen in a gas mixtures used in medical applications such as
Anesthesia, Respiratory therapy and is intended for adult, pediatric and
Neonatal populations.
These instruments may be used in verifying oxygen concentrations
in gas mixtures used in:
•

Anesthesia

•

Respiratory Therapy

•

Neonatal Care

1.5 Theory of Operation
The AX300-I analyzer can be divided into two major functional
groups:
•

R17MED Oxygen Sensor

•

Signal Processing

The analyzer uses Teledyne Analytical Instruments Patented
R17MED oxygen sensor. The millovolt output signal from the sensor is
fed into the electronic signal processor, where it is used to calculate the
oxygen gas concentration and display it on the LCD screen. There is no
concentration alarm in the AX300-I analyzer however a unique sensor
fail/disconnect alarm is incorporated to warn the user of a sensor
problem. The√ SENSOR indicator is illuminated on the LCD and the
audible and visual alarms are activated whenever a fault is detected.

1.5.1 Sensor
The AX300-I uses the Teledyne Class R17MED disposable oxygen
sensor. The sensor is made up of a sensing cathode and anode (fuel)
immersed in electrolyte and packaged in a small plastic container.
Oxygen entering the sensor reacts with the anode and a proportional
current is collected at the sensing cathode, which is sent to the
electronics where it is converted into a digital signal and displayed on
the LCD Screen.
Attached to the R17MED sensor is a removable plastic diverter.
This diverter is used to facilitate the transport of gas mixtures through

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Introduction

the sensor. The diverter, packaged separately when shipped, is necessary
when the tee adapter is used to sample gas flowing through a tube.
The diverter is not necessary and should not be used when the
sensor is placed directly in a chamber, or when the sensor is used in
confined volume analysis, such as incubators and inhalation tents.

CAUTION:

THE R17MED SENSOR CONTIANS A CAUSTIC
ELECTROLYTE AND LEAD. DO NOT TRY TO OPEN
THE SENSOR ASSEMBLY. CHECK THE SENSOR
REGULARLY FOR LEAKS. IF THE SENSOR IS
LEAKING, REPLACE IT. DO NOT TRY TO REPAIR IT.
CONTACT TELEDYNE FOR THE MATERIAL SAFETY
DATA SHEET RELATED TO HANDLING AND
DISPOSAL.

CAUTION:

REMOVE AND SAVE THE DIVERTER WHEN THE
SENSOR IS USED IN CONFINED VOLUME
APPLICATIONS.

1.5.2 Signal Processing
The electrical voltage developed in the sensor is sent to the electronics.
Processing includes amplification, conversion to digits, and comparison to
alarm set points if appropriate. Using a microprocessor allows for easier
setting of alarms, automatic calibration, and self-diagnosis.
The oxygen level is calculated and then displayed on the liquid
crystal display (LCD) on the front panel.
The audio alarm is triggered during a sensor disconnect alarm
condition. Pressing the ALARM SILENCE key () will provide an
audible alarm override.

BLANK

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Operation

AX300-I

Operation
Note: Upon receipt, INSPECT THE ENTIRE UNIT FOR
DAMAGE. Check the unit and all included accessories for
broken or loose parts. If damaged, DO NOT USE. Notify
the shipper, and consult Teledyne Analytical Instruments.
Note: This equipment is internally powered using 3 AA batteries.
CAUTION:

THE AX300-I, OXYGEN SENSOR AND ASSOCIATED
HARDWARE ARE NON-STERILE DEVICES. DO NOT
AUTOCLAVE THE INSTRUMENT OR SENSOR, AS
THIS WILL DAMAGE THE EQUIPMENT.

2.1 Setup
The AX300-I Portable Oxygen Analyzer is suitable for use in many
medical applications. The unit is equipped with a stand and can be used
on a tabletop or wall mounted using mounting bracket. An optional pole
mount clamp is also available.
To set up and use your AX300-I analyzer:
1. Install the sensor.
2. Install the batteries.
3. Calibrate the unit.
The control keys are designed for easy operation. A LOCK/UNLOCK
key has been supplied to prevent accidental changes to critical settings. This
eliminates unwanted changes in calibration or alarm settings from accidental
touching or bumping of the keys. To further reduce the possibly of incorrect
adjustments at least two keys must be pressed in order to modify a critical
calibration set point value.
Note: The ALARM SILENCE () key continues to operate
normally when the lock feature is activated.

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Operation

2.1.1 Sensor Installation or Replacement
Note: The R17MED oxygen sensor must be installed before the
oxygen analyzer/analyzer can be operated
1. Remove the new sensor from its protective bag. Inspect the
sensor for damage or electrolyte leakage. If the sensor is
damaged, obtain a replacement. Do not use the defective
sensor as it may damage the unit.
WARNING:

THE SENSOR ELECTROLYTE IS CAUSTIC. DO NOT
LET IT COME IN CONTACT WITH SKIN. IF IT DOES,
FLUSH AFFECTED AREA WITH WATER. DO NOT
ATTEMPT TO OPEN OR REPAIR THE SENSOR.

WARNING:

THE SENSOR ALSO CONTAINS LEAD. LEAKING OR
EXHAUSTED SENSORS SHOULD BE HANDLED AND
DISPOSED OF IN ACCORDANCE WITH LOCAL
REGULATIONS. CONTACT TELEDYNE FOR THE
MATERIAL SAFETY DATA SHEET

2. Plug one end of the coiled cable into the jack receptacle on the
back end of the R17MED sensor and secure in place with the
capture nut located at the base of the connector. See Figure 2-1.

Figure 2-1: Installing the R17MED Sensor

3. Plug the other end of the coiled cable into the receptacle located on
the right side of the unit and secure it in place using the capture nut.
See Figure 2-2.

Teledyne Analytical Instruments

Operation

AX300-I

Figure 2-2: Sensor Cable Connection to Analyzer
Note: When the AX300-I instrument is used for diffusion
sampling (i.e., incubators, tents, etc.), the plastic flow
diverter must be removed from the R17MED sensor. If the
sensor is used in breathing circuits, etc, the diverter must
be used as shown in Figure 2-3.

Figure 2-3: Mounting the Sensor in the Tee Adapter

2.1.2 Mounting
The AX300-I can be mounted in several ways depending on the
optional equipment ordered at the time of purchase. See Section 1.3.
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Portable Oxygen Analyzer

Operation

2.1.2.1 V-MOUNT ADAPTER INSTALLATION
The V-Mount Adapter consists of a matching plastic plate with
integral V-grooves that attach to the rear of the instrument.
To install V-Mount Adapter remove battery compartment door by
prying up the hinged latch at the bottom of the cover, then slide the
adapter plate into grooves provided in rear case. Replace the battery
compartment door and secure door latch. See Figure 2-4.
Note: The door latch is a tight fit onto the battery cover. Use a
coin to gently pry up the latch.

Figure 2-4: V-Mount Adapter Installation
2.1.2.2 UNIVERSAL MOUNTING CLAMP INSTALLATION
The Universal Mounting Clamp is supplied with a 1/4-20 screw for
securing the clamp to the rear of the instrument. A threaded brass insert is
installed on the back of the instrument for this purpose. See Figure 2-5.

Figure 2-5: Brass Insert for Universal Mounting Clamp

2.1.3 Battery Installation
Note: Three “AA” alkaline batteries must be installed in the unit
before the analyzer will operate. The unit must be
recalibrated whenever new batteries are installed.
To install the batteries:
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Operation

AX300-I

1. Turn the unit off (if it is on).
2. Hold the instrument face down in the palm of your hand. Use
a coin to pry up the latch that secures the battery
compartment door. Remove the battery compartment door.
CAUTION:

IMPROPER INSTALLATION OF THE BATTERIES
MAY RESULT IN DAMAGE TO THE UNIT AND
BATTERIES.

Note: Use alkaline batteries only. Other battery types will
produce erroneous battery test readings.
3. Install 3 “AA” alkaline batteries into the holder as shown in
Figure 2-6. Each battery has its own slot. To insure proper
polarity, place the bottom (flat) or negative end of the battery
in the end of the holder marked “–”. Place the top (button) or
positive end of the battery in the end of the holder marked
“+”. Do this for each battery.

Figure 2-6: Installing Batteries
4. Re-install the battery compartment door. When the unit is
first turned on the display will momentarily display all LCD
segments. During this period diagnostic tests are being
conducted to insure the circuits are functioning correctly.
The unit will activate the audible and visual alarms for about

1 second. The LCD will flash continuously indicating the
unit is in the unlocked position ready for calibration.
Note: When batteries are first installed or power is lost for any
reason the instrument defaults to the calibration mode. All
Teledyne Analytical Instruments

Portable Oxygen Analyzer

Operation

keys except the CAL and ON/OFF (I/O) keys are
inoperable until a successful calibration is achieved.
5. Note the battery display located below the oxygen readout
display. It continuously shows a bar graph of the remaining
life to the batteries. In the case of fresh batteries, it should
illuminate all 5 segments from the left to the right end of the
bar. The bar graph indicator is on continuously whenever the
instrument is powered on.

2.1.4 Calibration
The AX300-I should be calibrated before each use and every 8
hours to maintain accuracy.
Whenever new batteries are installed or
removed for any reason, the oxygen analyzer
defaults to the calibration mode with the LCD
display flashing 00.0. Only the CAL and
ON/OFF (I/O) keys are functional at this point.
Note: For first time and for routine
maintenance calibrations, make sure
the sensor and sensor cable are
installed correctly before attempting
to calibrate the instrument
To calibrate the instrument (See Figure 2-7):
1. Turn the unit on by pressing the ON/OFF (I/O) key.
2. Check the battery status via the bar graph.

Figure 2-7: Calibration S

3. If the LCD is not flashing, press the LOCK/UNLOCK key to
unlock the keys. LCD will flash indicating changes can be
made to the settings. If the batteries have just been installed
the LCD will flash 00.0
4.

As with most oxygen analyzer(s) the highest level of
accuracy is achieved when calibration is conducted using
100% oxygen. After installing the flow diverter as noted in
Section 2.1.1, insert the sensor into the plastic tee and
connect to a supply of pure dry oxygen flowing at 1-2 liters
per minute.

Note: An accessory calibration assembly (P/N C53790) is
available from Teledyne for use with the R17MED sensor

Teledyne Analytical Instruments

Operation

AX300-I

5. Wait about 20 seconds to insure the sample line is completely
purged with the calibration gas. Press the CAL key. The
LCD will count down from 9 to 0. During this time the
microprocessor is measuring the sensor output to determine
the gas concentration and selects the calibration range i.e.
100% or 20.9%. When the calibration is complete the LCD
will display the gas value. Press the LOCK/UNLOCK key to
save the calibration data.
Note: The AX300-I can only be calibrated using 100% oxygen or
room air 20.9%. Improper calibration or use of other gas
concentrations will activate the √ SENSOR indicator. To
repeat the calibration press the LOCK/UNLOCK key and
press the CAL key.
6. Remove the sensor from the oxygen supply and confirm the
LCD reads less than 22% in room air. It is not necessary for
it to read exactly 20.9%.
7. It is important to perform the calibration carefully and
thoroughly, using calibration gases that are free from
contaminates. Wait for a stable reading before locking in
calibration point. The accuracy of the instrument is only as
good as the procedure used to calibrate it.
Note: A single point air calibration is not recommended unless
the sensor can be exposed to a known source of fresh
outdoor air. Hospital room air is often enriched with
excess oxygen, which will introduce errors into the
calibration. Air calibration should only be used for
analyzing oxygen levels between 21% and 40% and
should never be used where a high degree of accuracy
is needed.
Note: Never calibrate the unit in humidified gas, as water vapor
makes the oxygen concentration appear lower than it really
is. See Section 2.3.1: Humidity.
CAUTION:

DO NOT ADJUST THE CALIBRATION SETTINGS IN
AIR AFTER THE 100% CALIBRATION, AS THIS WILL
CANCEL THE MORE ACCURATE 100%
CALIBRATION. THE 100% CALIBRATION MAY BE
REPEATED AS MANY TIMES AS DESIRED.

8. Press the LOCK/UNLOCK key to hold settings. The unit is
now ready for use.
Teledyne Analytical Instruments

Portable Oxygen Analyzer

Operation

2.1.5 Output 0-1 VDC or RS232
The AX300-I Portable Oxygen Analyzer provides signal outputs
for use with recorders and computers. These instruments are supplied
standard with a 0-1 VDC output. An optional 0-1 VDC Interface Cable
(P/N B-75554) is available from Teledyne for this purpose.
To connect the analyzer to an analog recording device:
1. Insert one end of the interface cable into the output port on
the side of the instrument. See Figure 2-8.
2. Insert the other end into the analog recorder device. Make
sure the device is equipped to handle a 0-1 VDC signal.
When properly calibrated, the output signal generated by the
analyzer is linear and proportional to the oxygen concentration.
If you requested Option-B (RS 232 digital output) at the time of
purchase, a digital RS 232 signal is output from the output port shown in
Figure 2-8. Use the optional RS 232 Interface Cable (P/N B-75555)
available from Teledyne for connection to a standard RS 232 port on a
computer or other suitably equipped digital device.

Figure 2-8: 0-1 VDC or RS 232 Digital Output Port
If your instrument is set for analog (0-1 VDC) output, you can
reconfigure it to use the digital output by changing a jumper on the
internal PC board.
To activate the digital output:
Teledyne Analytical Instruments

Operation

AX300-I

1. Remove the batteries and remove the five screws that hold the
case together.
2. Remove the rear case section leaving the PCB in the front half of
the case.
3. Remove jumper at position JP3 and reinstall it at position JP7.
4. Replace the rear cover and secure in place with five screws.
Install the batteries and recalibrate per Section 2.1.3.
CAUTION:

RECORDER/RS232 OUTPUT SIGNAL SHOULD ONLY
BE CONNECTED TO AN EN60601-1/IEC60606-1
APPROVED DEVICE.

To reconfigure the analyzer from a digital (RS 232) output to
analog (0-1 VDC) output, use the same procedure except in step 3
remove the jumper from JP7 and replace it at JP3.

2.2 Use
2.2.1 Procedure
Note: Prior to use, always test the batteries. Also check
calibration, the sensor for leaks and damage, and the
alarm settings.
The AX300-I instrument can be used to measure a gas mixture for
oxygen in two basic modes:
•

In the inhalation side of breathing circuit ahead of
antibacterial filters, humidifiers and medicating devices or
other instances where gases are flowing to a patient in
breathing circuits.

•

In confined volumes such as incubators or tents.

When analyzing for oxygen in breathing circuits, the flow diverter
must be used. The diverter should be screwed onto the threaded front
end of the R17MED sensor. A tee adapter (plastic, P/N A268, or metal,
P/N A283) should be placed into the circuit, and the above sensor
assembly plugged into the tee adapter. See Figure 2-3.

CAUTION:

CHECK THE BREATHING CIRCUIT FOR LEAKS. BE
CERTAIN THAT THE CIRCUIT DOWNSTREAM OF
THE SENSOR DOES NOT PRODUCE ANY

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Operation

BACKPRESSURE OR RESTRICTION TO FLOW.
ERRORS IN READINGS WILL RESULT IF THIS IS
NOT FOLLOWED.
THE OXYGEN SENSOR IS A NON-STERILE DEVICE
AND SHOULD BE USED IN CONJUCTION WITH AN
ANTIBACTERIAL FILTER. ALWAYS INSTALL THE
SENSOR ON THE INSPIRED LINE AHEAD OF
FILTERS, HUMIDIFIERS AND MEDICATING DEVICES.
NEVER INSTALL THE SENSOR IN A LOCATION
THAT WILL EXPOSE THE SENSOR TO PATIENTS
EXHALED BREATH OR SECRETIONS UNLESS YOU
INTEND TO DISPOSE OF THE SENSOR AND FLOW
ADAPTER AFTER USE.

When analyzing for oxygen in confined volumes such as
incubators, hoods, etc., the flow diverter must be removed from the
R17MED sensor so that it does not interfere with the rapid exchange of
gases to and from the sensing surface of the sensor.

CAUTION:

FAILURE TO REMOVE THE DIVERTER IN THESE
APPLICATION AREAS WILL RESULT IN A MARKED
LOWERING OF THE RESPONSE TIME OF THE
SENSOR.

The R17MED sensor can be placed or hung inside incubators, tents,
etc. When it is necessary to thread the cable through a small hole in
order to gain access to the inside of a chamber, the cable should be
disconnected at the sensor, threaded through the hole, and reconnected
inside the chamber.
The LOCK/UNLOCK key can be used to lock out any accidental
interference to the front panel keys. The LOCK/UNLOCK key acts as a
toggle, pressing LOCK/UNLOCK once renders inactive all keys except
the ALARM SILENCE () key. Pressing LOCK/UNLOCK a second
time unlocks the keypad.

Teledyne Analytical Instruments

Operation

AX300-I

2.3 Gas Sampling
2.3.1 Humidity
Humidity does not directly affect the accuracy of the sensor's
measurement. However, when a nebulizer or other device is used to
increase moisture levels in gas mixtures, the moisture actually dilutes
the mixture. This dilution effect decreases the oxygen concentration.
For example, if an 80% oxygen gas mixture is humidified to
saturation at room temperature, the resulting gas mixture will contain
only 77.5% oxygen. Your portable oxygen analyzer accurately measures
decreases in the oxygen concentration due to the dilution effects of
moisture added to gas mixtures.
As with all oxygen sensors, excessive condensation on the sensing
surface of the R17MED will block the diffusion of oxygen to the sensor,
rendering it inoperative. We recommend installing the sensor on the dry
side of the breathing circuit at all times.

2.3.2 Temperature
The R17MED oxygen sensor adjusts for ambient temperature
changes in the range of 0–40°C (32–106°F). Since the thermistor that
compensates for these changes is located in the rear of the sensor
assembly, it is important that gas mixtures, flowing over the front of the
sensor, be at room temperature. Reading errors may occur if hot gases
from a heated humidifier are directed past a sensor teed into a breathing
circuit.
A small thermal tracking error may be encountered in application
areas where the entire sensor assembly is placed in the gas mixture to be
analyzed (e.g., incubators). Holding the sensor in your hand for more
than a few minutes can also affect the temperature tracking which
appears as a slow drift on the LCD. No adjustments should be made
during this period since this error will be eliminated when both the
thermistor and sensing electrode have had sufficient time to come to
thermal equilibrium. This can take up to 2 hours.

2.3.3 Pressure
Virtually all gas sensors and analyzers measure the partial pressure,
not the percentage, of the gas that they sense. The only time that these
instruments can accurately read percentages is when the total pressure
does not vary over time between calibrations and use. For this reason it
is important to calibrate the AX300-I oxygen sensor at regular intervals.
Teledyne Analytical Instruments

Portable Oxygen Analyzer

Operation

It is recommended that the unit be calibrated prior to each use or every 8
hours.
When the sensor is connected to a ventilator circuit, the alternating
“breathing” pressure cycles generated by the ventilator will be sensed as
an increase in the oxygen percentage (especially if the sensor is fast
enough to sense the changes, as is the R17MED). In reality, the
percentage of oxygen is not changing; it is the total pressure that is
increasing producing a corresponding increase in the partial pressure of
oxygen. A hundred centimeter of water pressure pulse will produce a
0.11 atmosphere, or an 11% increase in the total and therefore partial
pressure of oxygen. Assuming that the sensor is fast enough to track this
pressure pulse, an un-pressurized reading of 50% oxygen will increase
to 55.3% if the sensor is subjected to a pressure cycle of 100cm H2O.
The reading will rise proportionally less for smaller pressures.

2.3.4 Discrepancy in Readings
The AX300-I instrument should be used to measure the oxygen
concentration exiting another oxygen mixing device or life support
system (i.e., a blender, incubator or anesthesia machine). The
information obtained from the AX300-I should never be used to adjust a
life-support system, but should only be used as an indication that the life
support system or device may require service and/or calibration.
When a discrepancy in oxygen readings is detected, the oxygen
analyzers readings should be verified by checking the AX300-I battery
condition and calibration using 100% oxygen. If the analyzer can be
calibrated, the unit can be assumed to be in good working order and
capable of providing readings to specification. If, after reinstalling the
unit, the discrepancy in oxygen readings persists, the problem is most
likely elsewhere (i.e., flow blockage, primary device error, etc.). Further
investigation should be made until the discrepancy in readings is
resolved. The troubleshooting section of this manual may provide
additional assistance in locating the problem.
Note: The MSDS on this material is available upon request
through the Teledyne Environmental, Health and Safety
Coordinator. Contact at (626) 934-1592

2.3.5 Anesthetic Gases
2.3.5.1 GASES THAT INDUCE READING ERROR
When using the R17MED sensor in the presence of anesthetic gases
such as Halothane, the oxygen reading may fall (see Table below). The
Teledyne Analytical Instruments

Operation

AX300-I

magnitude of this error will depend upon the level of oxygen and the
duration of exposure.
The anesthetic agents listed in the following table (Halothane,
Enflurane, Isoflurane, Sevoflurane, and Desflurane) were vaporized into
a stream of 30% oxygen / 70% nitrous oxide, and the resulting drops in
oxygen level after an exposure of approximately two hours were noted.
Exposures in excess of two hours may produce slightly greater
errors. The errors listed are typical for all oxygen sensors such as the
R17MED. Exposing the sensor to air or gases that do not contain
anesthetic agents for a period of time equal to or greater than the exposure
interval will eliminate the reading error in most cases.

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Operation

Table 2-1: Oxygen Reading Error in a Mixture of Anesthetic Gas
Gas or Vapor Level
(Balance: Mixture of 30% O2 / 70% N2O, except where noted)
Gas or Vapor

Test Level

Oxygen Reading
Error

Helium

50%, balance O2

Nitrous Oxide

80%, balance O2

Carbon Dioxide

10%, balance O2

Halothane

< 1.5% O2 *

Enflurane

< 1.5% O2 *

Isoflurane

< 1.5% O2 *

Sevoflurane

< 1.5% O2 *

Desflurane

15%

< 1.5% O2 *

* Errors are approximate and may vary based on exposure times and
concentrations.
These performances meet or exceed the requirements of ISO 7767:
1997 (E).
CAUTION:

THE AX300-I SHOULD NOT BE USED IN THE
PRESENCE OF FLAMMABLE ANESTHETICS SUCH
AS DIETHYL ETHER OR CYCLOPROPANE.

CAUTION:

THE AX300-I, OXYGEN SENSOR AND ASSOCIATED
HARDWARE ARE NON-STERILE DEVICES. DO NOT
AUTOCLAVE THE INSTRUMENT OR SENSOR, AS
THIS WILL DAMAGE THE EQUIPMENT.

2.3.5.2 CARE AFTER USE IN NITROUS OXIDE
CAUTION:

THE R17MED SENSOR SHOULD NOT BE LEFT IN
NITROUS OXIDE MIXTURES ANY LONGER THAN
ABSOLUTELY NECESSARY.

Operation

AX300-I

oxygen reading continues to drop after each use in nitrous oxide the
sensor should be removed from service. If the sensor can no longer be
calibrated or if there is any sign of electrolyte leakage, the sensor should
be disposed of in accordance with local regulations and the Material
Safety Data Sheet (MSDS) available through Teledyne.

2.3.6 Cleaning
The AX300-I and R17MED sensor are non-sterile devices.
The oxygen analyzer, oxygen sensor, and sensor interconnection
cable may be cleaned by wiping the surfaces with isopropyl alcohol or a
mild cleaning solution.
Before placing instrument in operation make sure all surface are
dry and unit is properly calibrated.
When cleaning do not allow liquids or moisture to enter the
instrument or sensor internal cavities. Do not allow the cleaning solution
to come in contact with the electrical connections. Do not immerse the
instrument, oxygen sensor or sensor interconnection cable in water or
any other liquid.
Do not expose the instrument, oxygen sensor and interconnection
cable to steam, ethylene oxide, or radiation sterilization.

2.4 Do’s and Don’ts
– DO –
•

Read all of the directions before using for the first time.

•

Calibrate every 8 hours or before every use.

•

Visually inspect the sensor for leakage before each use.

•

Calibrate using 100% oxygen and check in air.

•

Test batteries regularly and replace when battery indicator
shows low battery (no bars remaining)

•

Make sure keys are locked by using the LOCK/UNLOCK
key feature.

•

Keep the unit, sensor and connections dry, or on the dry side
of the breathing circuit.

•

Recalibrate after replacing the batteries.
Teledyne Analytical Instruments

Portable Oxygen Analyzer

Operation

•

Recalibrate after replacing the sensor.

•

Use properly installed alkaline batteries only.

•

Make sure the R17MED sensor is properly attached.

•

Remove the plastic flow diverter only when using the tee adapter.

•

Remove and save the plastic flow diverter when using the
sensor in non-flowing applications (incubators, tents, etc.)

•

Clean the case with isopropyl alcohol or mild detergent only.

– DON’T –
•

Use this analyzer if you suspect any malfunction.

•

Use the instrument in the presence of flammable gases.

•

Use anything but alkaline batteries.

•

Autoclave or freeze the sensor or instrument.

•

Open or try to repair a leaking or broken sensor.

•

Immerse the unit or sensor in any liquid.

•

Pass hot or cold gas mixtures over the sensor.

•

Adjust the reading in air after 100% calibration

•

Expose the unit to devices that produce high levels of radio,
short wave, microwave, x-ray, or high frequency
interference.

•

Use cleaning agents or liquids in the cable receptacles or
around the battery compartment.

•

Place the unit itself in a water vapor-saturated environment.

•

Expose the LCD to excessive sunlight.

•

Expose the unit to a condensing water environment such as a
mist tent.

Teledyne Analytical Instruments

Operation

AX300-I

BLANK

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Service Manual

Service Manual
3.1 General Service Information
The Teledyne Model AX300-I portable oxygen analyzer is designed to be
robust yet compact in size. In order to achieve maximum reliability in a
microprocessor-based instrument, a single PC board is used which relies exclusively
on surface mount technology. Without access to specialized probes and test
equipment, troubleshooting and repair of circuit board components are not feasible.
A factory replacement of the entire PC board is more cost effective than a field
repair of an individual component.
With the exception of replacing the sensor or batteries there are no userserviceable components inside the unit. There are no potentiometers or other
adjustments to be made within this instrument. If a problem arises with either of
these models that cannot be corrected by recalibration, changing the batteries or
replacing the sensor as described in this manual, the unit must be sent back to the
factory for repair or replacement. See Section 3.10 for instructions on obtaining a
Return Merchandise Authorization (RMA) number before sending a unit back to
Teledyne for repair.

3.2 Overall Maintenance
The AX300-I instrument requires very little maintenance, other than
calibration, checking and changing the batteries and sensor, and cleaning the
plastic housing. Occasional cleaning of the plastic surface can be done with
isopropyl alcohol. Should any part of the instrument malfunction or fail to
perform, the unit should be removed from service. There are no user-serviceable
components within the instrument.

3.3 Battery Maintenance
DO: Test batteries regularly. (replace immediately when all 5 bars are
missing).
DO: Always use alkaline batteries.
DO: Recalibrate after replacing batteries.
The AX300-I instrument incorporates a bar graph that continuously displays
the approximate amount of useful life remaining on the set of installed batteries.

Teledyne Analytical Instruments

Service Manual

AX300-I

Excessive alarm activation will wear down the battery faster than usual. The
minimum detectable change in battery voltage corresponds to an increment of
about 50 hours, meaning that the battery voltage reading may not change for
several hours at a time.
If the analyzer is not used for a period of 30 days or more, the batteries
should be removed prior to storage.

3.4 Sensor Maintenance
DO: check the sensor for damage or leaks before use.
DO: recalibrate after replacing the sensor.
DON’T: immerse the R17MED sensor in liquid.
DON’T autoclave the R17MED sensor.
DON’T: open or try to repair the sensor.
Before every use, the sensor, cable and connections should be checked.
Check the sensor for leaks and condensation. Check the cable for splitting or
cracked insulation. Make sure the connections are tight and dry.
In the event that the sensor has been damaged, consult the Material Safety
Data Sheet in the Appendix for handling guidelines.

3.5 Calibration
Incorrect readings can often traced to improper calibration. The AX300-I
should be calibrated before each use and every 8 hours to maintain accuracy. It
must be calibrated whenever new batteries are installed. Calibration using
methods other than described below can lead to improper operation and are
discouraged.
Whenever new batteries are installed or removed for any reason, the oxygen
analyzer defaults to the calibration mode with the LCD display flashing 00.0.
Only the CAL and ON/OFF (I/O) keys are functional at this point.
To calibrate the instrument refer back to Section 2.1.4.
.

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Service Manual

3.6 Gas Sampling
3.6.1 Humidity
Humidity does not directly affect the accuracy of the sensor's measurement.
However, when a nebulizer or other device is used to increase moisture levels in
gas mixtures, the moisture actually dilutes the mixture. This dilution effect
decreases the oxygen concentration.
For example, if an 80% oxygen gas mixture is humidified to saturation at
room temperature, the resulting gas mixture will contain only 77.5% oxygen.
Your portable oxygen analyzer accurately measures decreases in the oxygen
concentration due to the dilution effects of moisture added to gas mixtures.
As with all oxygen sensors, excessive condensation on the sensing surface
of the R17MED will block the diffusion of oxygen to the sensor, rendering it
inoperative. We recommend installing the sensor on the dry side of the breathing
circuit at all times.

3.6.2 Temperature
The R17MED oxygen sensor adjusts for ambient temperature changes in the
range of 0–40°C (32–106°F). Since the thermistor that compensates for these
changes is located in the rear of the sensor assembly, it is important that gas
mixtures, flowing over the front of the sensor, be at room temperature. Reading
errors may occur if hot gases from a heated humidifier are directed past a sensor
teed into a breathing circuit.
A small thermal tracking error may be encountered in application areas
where the entire sensor assembly is placed in the gas mixture to be analyzed
(e.g., incubators). Holding the sensor in your hand for more than a few minutes
can also affect the temperature tracking which appears as a slow drift on the
LCD. No adjustments should be made during this period since this error will be
eliminated when both the thermistor and sensing electrode have had sufficient
time to come to thermal equilibrium. This can take up to 2 hours.

3.6.3 Pressure
Virtually all gas sensors and analyzers measure the partial pressure, not the
percentage, of the gas that they sense. The only time that these instruments can
accurately read percentages is when the total pressure does not vary over time
between calibrations and use. For this reason it is important to calibrate the
AX300-I oxygen sensor at regular intervals. It is recommended that the unit be
calibrated prior to each use or every 8 hours.

Teledyne Analytical Instruments

Service Manual

AX300-I

When the sensor is connected to a ventilator circuit, the alternating
“breathing” pressure cycles generated by the ventilator will be sensed as an
increase in the oxygen percentage (especially if the sensor is fast enough to sense
the changes, as is the R17MED). In reality, the percentage of oxygen is not
changing; it is the total pressure that is increasing producing a corresponding
increase in the partial pressure of oxygen. A hundred centimeter of water
pressure pulse will produce a 0.11 atmosphere, or an 11% increase in the total
and therefore partial pressure of oxygen. Assuming that the sensor is fast enough
to track this pressure pulse, an un-pressurized reading of 50% oxygen will
increase to 55.3% if the sensor is subjected to a pressure cycle of 100cm H2O.
The reading will rise proportionally less for smaller pressures.

3.6.4 Discrepancy in Readings
The AX300-I instrument should be used to measure the oxygen
concentration exiting another oxygen mixing device or life support system (i.e., a
blender, incubator or anesthesia machine). The information obtained from the
AX300-I should never be used to adjust a life-support system, but should only be
used as an indication that the life support system or device may require service
and/or calibration.
When a discrepancy in oxygen readings is detected, the oxygen analyzers
readings should be verified by checking the AX300-I battery condition and
calibration using 100% oxygen. If the analyzer can be calibrated, the unit can be
assumed to be in good working order and capable of providing readings to
specification. If, after reinstalling the unit, the discrepancy in oxygen readings
persists, the problem is most likely elsewhere (i.e., flow blockage, primary
device error, etc.). Further investigation should be made until the discrepancy in
readings is resolved. The troubleshooting section of this manual may provide
additional assistance in locating the problem.
Note: The MSDS on this material is available upon request through the
Teledyne Environmental, Health and Safety Coordinator. Contact
at (626) 934-1592

3.6.5 Anesthetic Gases
3.6.5.1 GASES THAT INDUCE READING ERROR
When using the R17MED sensor in the presence of anesthetic gases such as
Halothane, the oxygen reading may fall (see Table below). The magnitude of this
error will depend upon the level of oxygen and the duration of exposure.
The anesthetic agents listed in the following table (Halothane, Enflurane,
Isoflurane, Sevoflurane, and Desflurane) were vaporized into a stream of 30%
Teledyne Analytical Instruments

Portable Oxygen Analyzer

Service Manual

oxygen / 70% nitrous oxide, and the resulting drops in oxygen level after an
exposure of approximately two hours were noted.
Exposures in excess of two hours may produce slightly greater errors. The
errors listed are typical for all oxygen sensors such as the R17MED. Exposing the
sensor to air or gases that do not contain anesthetic agents for a period of time
equal to or greater than the exposure interval will eliminate the reading error in
most cases.
Table 3-1: Oxygen Reading Error in a Mixture of Anesthetic Gas
Gas or Vapor Level
(Balance: Mixture of 30% O2 / 70% N2O, except where noted)
Gas or Vapor

Test Level

Oxygen Reading
Error

Helium

50%, balance O2

Nitrous Oxide

80%, balance O2

Carbon Dioxide

10%, balance O2

Halothane

< 1.5% O2 *

Enflurane

< 1.5% O2 *

Isoflurane

< 1.5% O2 *

Sevoflurane

< 1.5% O2 *

Desflurane

15%

< 1.5% O2 *

* Errors are approximate and may vary based on exposure times and
concentrations.
These performances meet or exceed the requirements of ISO 7767: 1997 (E).
CAUTION:

THE AX300-I SHOULD NOT BE USED IN THE PRESENCE OF
FLAMMABLE ANESTHETICS SUCH AS DIETHYL ETHER OR
CYCLOPROPANE.

CAUTION:

THE AX300-I, OXYGEN SENSOR AND ASSOCIATED
HARDWARE ARE NON-STERILE DEVICES. DO NOT
AUTOCLAVE THE INSTRUMENT OR SENSOR, AS THIS WILL
DAMAGE THE EQUIPMENT.

Teledyne Analytical Instruments

Service Manual

AX300-I

3.6.5.2 CARE AFTER USE IN NITROUS OXIDE
CAUTION:

THE R17MED SENSOR SHOULD NOT BE LEFT IN NITROUS
OXIDE MIXTURES ANY LONGER THAN ABSOLUTELY
NECESSARY.

After exposure to nitrous oxide mixtures, the sensor should be left in 100%
oxygen overnight (e.g., left in a breathing circuit that has been flushed with pure
oxygen). If this is not practical, when using the tee, remove the plastic flow
diverter and leave the sensor in room air. If the oxygen reading continues to drop
after each use in nitrous oxide the sensor should be removed from service. If the
sensor can no longer be calibrated or if there is any sign of electrolyte leakage,
the sensor should be disposed of in accordance with local regulations and the
Material Safety Data Sheet (MSDS).
Note: The MSDS on this material is available upon request through the
Teledyne Environmental, Health and Safety Coordinator. Contact
at (626) 934-1592

3.7 Troubleshooting
The AX300-I oxygen analyzer provides a variety of built-in safety features that
prevent its use when a fault is detected. When a unit displays the message √ SENSOR
and sounds the audible and visual alarm continuously, it is an indication of a faulty
connection between the sensor and the unit or an expired or faulty sensor. To
determine where the difficulty lies, refer to the following guidelines in Table 3-2.

Table 3-2 Troubleshooting
Symptom

Why

What To Do

New sensor responds
slow or drifts.

If the sensor is new
and was just
removed from its
sealed bag it may
need to run for
several hours.

A) Wait 1–2 hours and
recalibrate.

Sensor will not read
below 22 % after
calibration in 100% O2.

Calibration in 100%
was invalid or the
room air is
contaminated with
excess oxygen.

A) Recalibrate using dry gas
making sure the reading
stabilizes before making
any adjustments.
B) Make sure that at least 6" (30
cm.) of tubing is attached to
the exhaust side of the tee

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Service Manual

adapter to prevent back filling.
O2 flow rate should not
exceed 5 l/min.
C) Oxygen concentration at the
sensor is significantly higher
than 21%. Take the
instrument to a wellventilated area and check
the reading again.
E) Try calibrating with a known
good sensor; if this fails, see
symptom "Reading drifts
over 2–3%..."
The sensor does not
react to changes in
oxygen concentration,
or the readings are
unstable and drifting.

Water is condensing
on the sensing
surface.
Electrical interference
is disrupting the
electronics

A) Remove the sensor from tee
adapter and unscrew the
plastic flow diverter. Using
absorbent tissue or cotton
swab, gently wipe off sensing
surface inside threaded
portion of sensor assembly.
B) Relocate unit away from
sources of electrical noise
such as cauterizing equipment
and two-way radios.

The display is flashing

√ SENSOR

The unit has detected
a fault in the signal
from the sensor.
Sensor has expired.
The sensor has been
exposed to a gas
containing little or no
oxygen.

A) Check sensor cable
connections and make sure
they are completely
inserted into the mating
connector and the capture
nut is firmly in place.
B) Expose the sensor in 100%
O2 and check calibration.
C) The sensor output has
fallen to a level where it is
no longer usable. Replace
sensor.

The oxygen reading
fluctuates or appears to
be incorrect.

Like all O2 sensors,
the R17MED detects
the changes in the
partial pressure of
O2.

A) During calibration, make
sure there is no restrictions
on exhaust side of sensor. If
the reading changes with
flow, the sensor is
pressurized or there may be
a leak in the system.
B) If a high degree of accuracy
is desired, or the

Teledyne Analytical Instruments

Service Manual

AX300-I

concentration of O2 is in
excess of 40%, calibration
with 100% is recommended.
C) If humidified gas is used to
ventilate the patient, water
vapor actually dilutes the
gas. See Appendix:
Humidity, Temperature.
D) If a blender is used, check
its calibration. See
Appendix: Discrepancy in
Readings.
The unit has stopped
working and the LCD is
displaying
alphanumeric figures.

The AX300-I unit is
equipped with an
electronic "watch dog,"
which analyzers the
circuitry within the unit
for potential faults and
renders the unit
inoperable until the
condition is corrected.
(See Watch dog
section below)
Several conditions can
activate the "watch
dog." Dropping the
unit, poor battery
connections, and radio
frequency interference
are the most common
causes. See the watch
dog section for
additional information

No display.

A) Disconnect the batteries and
inspect the contacts for
corrosion. Reconnect the
batteries. If the unit functions
properly, calibrate the unit
and reset the alarm values.
B) Try a new set of batteries.
C) Increase the distance
between the unit and any
source of radio frequency
interference. The sensor
cable is a prime source of
pickup as it can act like an
antenna. Relocate the
sensor cable and if possible
change its coiled length to
“de-tune” its antenna effect.
Placing the cable in a
different position may also
help.

A) Batteries expired.

A) Check/replace batteries.

B) Bad battery
connection.

B) Check battery connections.

Keys inoperable/cannot
turn unit off

The LOCK/UNLOCK
key is activated which
is preventing key
operation

A) Press LOCK/UNLOCK key
once. LCD will flash
indicating keys are active.

Cannot adjust
calibration

Critical settings require
two keys be pressed in
a specific order.

A) If display is not flashing
press lock key once to
activate keys. Press desired
function followed by the Up
and Down key.

LOCK/UNLOCK key is
active

C) Calibrate.

Teledyne Analytical Instruments

Portable Oxygen Analyzer

Service Manual

Note: In the event that none of these procedures produce desired results, remove
the batteries and return the unit to Teledyne for repair.

3.8 Watchdog
The AX300-I is equipped with a watchdog circuit that continuously analyzers the
electronics for proper operation. If the watchdog detects a failure, one of the following
codes will appear on the LCD.
The error codes can appear on the LCD when batteries are first installed,
during normal operation or if the unit is subjected to extreme shock. In some
cases an additional digit is used in the error code to supply additional
information. For example, the error code 6 and 7 are followed by another digit
listed as (N) in Table 3.3. The error code 65 would indicate that a key is stuck
and this key is the Silence key.
In addition to supplying visual error codes, the audio device will beep a
number of times to indicate the general error in case the display is not functional.
Note: To reset the watchdog error code. Remove one battery for 5
seconds and replace. If the error persists contact your locale
representative or Teledyne for assistance.
Table 3-3 Error Codes
Error Code

Audio Beeps

Error

Indeterminate

The watchdog timer has timed out indicating
a serious software error

Analog output is different from the expected
value. May indicate a shorted or over-loaded
analog output or a failure of the analog to
digital converter or digital to analog
converter circuit.

The ADC circuit failed during POST.

Teledyne Analytical Instruments

Service Manual

6 (5)

AX300-I

6
(There is no
indication of
which key is
stuck)

A stuck key has been detected. The second
digit example (5) on the display shows
which key is stuck:
1 - Batt
2 - Cal
5 - Silence
8 - Key Lock

7(2)

7
(There is no
indication of
the type of
DAC failure)

A failure has occurred during the automatic
calibration of the digital to analog converter
(DAC) circuit. The second digit example (2)
shows the type of digital to analog failure.
0 - Measurement
1 - High Test
2 - Low Test
3 - Offset Cal
4 - Gain Cal

3.9

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