Teledyne GFC-7000E - Trace CO2 Analyzer - Manual (Page 213)

Model GFC7000E Instruction Manual TROUBLESHOOTING & REPAIR PROCEDURES
04584 Rev A1 202
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.
11.4.6. Sensor Assembly
11.4.6.1. Sync/Demodulator Assembly
To verify that the Sync/Demodulator Assembly is working follow the procedure below:
1. Verify that D1 and D2 are flashing.
• If not check the opto pickup assembly, Section 11.4.6.2 and the GFC wheel drive, Section
11.4.6.3
• 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 11.4.6.4.
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.
• If they are not then either the sync demodulator board or the IR-photodetector are bad.
See also section 11.3.1.4 for problems with the IR-Photodetector TEC drive.
11.4.6.2. Opto Pickup Assembly
Operation of the opto pickup PCA (04088) can be verified with a voltmeter. Measure the AC and
DC voltage between digital ground on the Relay board, or Keyboard and TP1 and TP2 on the sync
pickup PCA. For a working board, with the GFC motor spinning, they should read 2.4 ±0.1 VAC
and 2.5 ±0.15 VDC.
Further confirmation that the pickups and motor are operating properly can be obtained by
measuring the frequency at TP1 and TP2 using a frequency counter, a digital volt meter with a
frequency counter, or an oscilloscope per the table below.
Table 11-9: Opto Pickup Board Nominal Output Frequencies
NOMINAL MEASURED FREQUENCY
AC MAINS FREQ. TP1 TP2
50 Hz 25 300
60 Hz 30 360