Teledyne GC-Pro/FID - Gas Chromatograph - Manual (Page 106)

Maintenance GC-Pro FID
Teledyne Analytical Instruments 92
the ohmmeter indicates an open thermistor. (If the thermistor is hot,
the resistance will be much lower.)
3. Check the anode-igniter coil for continuity by measuring
between pins J4-1&2 of the disconnected cable plug. The
ohmmeter should indicate a short circuit.
4. If either step 2 or 3 does not check as indicated, remove the
electrode assembly of the detection cell and replace it. If the
quartz flame tip is damaged, the top section of the cell may be
removed by disconnecting the vent line, and removing the screws
around its flange. Return the unit complete with attached
electrode cable. If steps 2 and 3 both check out properly,
reconnect the anode-igniter cable.
5. Check K1 and K2 relays operation as the analyzer is RE-
IGNITING. If the relays do not energize, remove the flame guard
power supply board and check the forward and backward
resistance of its transient suppression diode by measuring pins 13
and 14 of the relay socket. The ohmmeter should indicate a short
circuit resistance in one direction and some resistance value
when the leads are reversed. If the indication is a short circuit,
then the diode must be replaced.
Note: If, after replacing a defective diode, the circuit still does not
work properly, the flame guard circuit components have
been damaged, and the PC board must be replaced.
6. If the preceding steps check out correctly, the flame guard
portion of the circuitry on the flame guard/anode power supply
PC board is defective.
IMPORTANT: If the circuit proves defective, the analyzer will
have to be recalibrated after the board is
replaced.
5.4 Sampling System
If the procedures outlined above do not correct the problem, the fault
must be related to the gas control systems. Plugged or faulty regulators,
plugged restrictors, or leaks within the system can cause erratic
performance. TAI recommends that the factory or an authorized
representative be contacted before attempting any repairs to the sample
or supporting gas systems within the analyzer.