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Low Flow:
1. Check for leaks as described in Section 11.2. Repair and re-check.
2. Check for dirty sample filter or dirty orifice filter(s).
3. Check for partially plugged pneumatic lines, orifices, or valves.
High Flow:
1. The most common cause of high flow is a leak around an orifice. To
correct, remove the orifice as described in Section 11.5, replace O-rings,
and re-assemble.
10.6.2 Troubleshooting temperature problems
The Model 300 has been designed to operate at ambient temperatures between 5
o
C and
40
o
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:
• Sample Temperature
• Inside Chassis Temperature
• Optical Bench Temperature
• Gas Filter Wheel Temperature
and controls the temperatures of two components by heating:
• Optical Bench
• 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.
P/N 02163G1 Teledyne API Model 300 CO Analyzer Instruction Manual - Page 91