Teledyne gfc 7000ta Sensor Assembly, Sync/Demodulator Assembly, Relay Board Control Devices

Troubleshooting Model GFC7000TA Carbon Dioxide Analyzer

10.5.6. Relay Board

The relay board PCA (04135) can be most easily checked by observing the condition of the its status LEDs on the relay board, as described in Section 10.1.4.3, and the associated output when toggled on and off through signal I/O function in the diagnostic menu, See Section 10.1.3.

1.If the front panel display responds to button presses and D1 on the relay board is not flashing, then either the I2C connection between the motherboard and the relay board is bad, or the relay board itself is bad.

2.If D1 on the relay board is flashing and the status indicator for the output in question (heater power, valve drive, etc.) toggles properly using the signal I/O function, then the associated control device on the relay board is bad. Several of the control devices are in sockets and can be easily replaced. The table below lists the control device associated with a particular function:

Table 10-8: Relay Board Control Devices

FUNCTION	CONTROL	IN SOCKET
	DEVICE
Wheel Heater	K1	Yes
Bench Heater	K2	Yes
Spare AC Control	K3	Yes
IZS Valves	U4	Yes
IR Source Drive	U5	No

The IR source drive output can be verified by measuring the voltage at J16 with the IR source disconnected. It should be 11.5± 0.5 VDC.

10.5.7. Sensor Assembly

10.5.7.1. Sync/Demodulator Assembly

To verify that the Sync/Demodulator Assembly is working follow the procedure below:

1.Verify that D1 and D2 are flashing (they flash at different rates, see Table 11-3).

∙If not check the opto pickup assembly, Section 10.5.7.2 and the GFC wheel drive, Section 11.5.6.3.

∙If the wheel drive and opto pickup are working properly then verify that there is 2.4 ±0.1 VAC and 2.5 ±0.15 VDC between digital ground and TP 5 on the sync demod board. If not then check the wiring between the sync/demod and opto pickup assembly (see interconnect drawing 04216). If good then the sync/demod board is bad.

2.Verify that the IR source is operating, Section 10.5.7.4.

3.With the analyzer connected to zero air, measure between TP11 (measure) and analog ground, and TP12 (reference) and analog ground.

∙If they are similar to values recorded on the factory data sheet then there is likely a problem with the wiring or the A/D converter.

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