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Teledyne API Model T360/T360M Operation Manual Troubleshooting and Service
245
Using the BENCH_HEATER parameter under the signal I/O function, as
described above, turn on and off K2 (D3 on the relay board should illuminate
as the heater is turned on). Check the AC voltage present between pin 2
and 4, for a 100 or 115 VAC model, and pins 3 and 4, for a 220-240 VAC
model.
3. If the relay has failed there should be no change in the voltage across pins 2
and 4 or 3 and 4. NOTE: K2 is in a socket for easy replacement.
4. If K2 checks out OK, the thermistor temperature sensor located on the optical
bench near the front of the instrument could be at fault. Unplug the
connector labeled “Bench”, and measure the resistance of the thermistor. At
room temperature it should have approximately 30K Ohms resistance near
the 48
o
C set point it should have ~12K ohms.
8.4.1.3. GFC WHEEL TEMPERATURE
Like the bench heater above there are three possible causes for the GFC wheel
temperature to have failed.
1. The wheel heater has failed. Check the resistance between pins 1 and 4 on
the white five-pin connector just below the sample temperature sensor on the
bench (pin 1 is the pointed end). It should be approximately 275 ohms.
2. Assuming that the I
2
C bus is working and that there is no other failure with
the relay board, the solid-state relay (K1) on the relay board may have failed.
Using the
WHEEL_HEATER parameter under the signal I/O function, as
described above, turn on and off K1 (D2 on the relay board should illuminate
as the heater is turned on). Check the AC voltage present between Pin 1
and Pin 4.
WARNING:
HAZARDOUS VOLTAGES ARE PRESENT DURING THIS TEST
3. If the relay has failed there should be no change in the voltage across pins 1
and 4. NOTE: K1 is socketed for easy replacement.
4. If K1 checks out OK, the thermistor temperature sensor located at the front of
the filter wheel assembly may have failed. Unplug the connector labeled
“Wheel”, and measure the resistance of the thermistor. The resistance near
the 68
o
C set point is ~5.7k ohms.
8.4.1.4. IR PHOTO-DETECTOR TEC TEMPERATURE
If the PHT DRIVE test parameter described earlier in Table 8-2 is out of range
there are two four possible causes of failure.
1. The screws retaining the IR photo detector to the absorption bench have
become loose. Carefully tighten the screws, hand-tight and note whether,
after the analyzer has come up to operating temperature, whether the
PHT
DRIVE voltage has returned to an acceptable level.
07272B DCN6552