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Teledyne API Model 401 O
3
Photometric Calibrator Instruction Manual, 01124, Rev. J2
9.6.2 Troubleshooting Temperature Problems
The Model 401 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 inlets 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. Source Lamp Temperature
4. O
3
GEN Lamp Temperature
The instrument controls the temperatures of two components by heating:
1. Source Lamp
2. O
3
GEN Lamp
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 95K 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.
Source Lamp Temperature
Unplug the connector at Motherboard J4 and measure across the leads.
O
3
GEN Lamp Temperature
Unplug the connector at Motherboard J6 and measure across the leads.
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