Troubleshooting Temperature Problems - Teledyne 300M Instruction Manual

Teledyne API Model 300M CO Analyzer Instruction Manual, 04033, Rev. A

10.6.2 Troubleshooting Temperature Problems

The Model 300M has been designed to operate at ambient temperatures between 10°C and 40°C.
As a first step in troubleshooting temperature problems, confirm the ambient temperature is
within this range and that the air inlet slots on the sides of the cover and the fan exhaust on the
rear panel are not obstructed.
The instrument monitors four temperatures:
1. Sample Temperature
2. Inside Chassis Temperature
3. Optical Bench Temperature
4. Gas Filter Wheel Temperature
and controls the temperatures of two components by heating:
1. Optical Bench
2. Gas Filter Wheel
If any of the temperature readings appear to be incorrect, check for proper thermistor operation
by measuring the resistance of the thermistor(s). This resistance should be in the range of 7.6K
ohms to 95 ohms. If it is not, the thermistor is defective and should be replaced. Points for
measuring thermistor resistance are as follows:
Sample Temperature:
Unplug the connector at Motherboard J2 and measure across the leads.
Optical Bench Temperature:
Unplug the connector at Motherboard J4 and measure across the leads.
Gas Filter Wheel Temperature:
Unplug the connector at Motherboard J5 and measure across the leads.
Chassis Temperature:
Turn the analyzer off and remove the DC Power Supply Board. Measure across Motherboard J21
pins A30 and C30.
If thermistor resistance(s) are within the proper range, check the temperature linearzation circuits
on the DC Power Supply Board as described in Section 10.6.4.
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