Unstable Zero; Inability To Span - Teledyne 6400A Instruction Manual

TAI Model 6400A SO

9.2.7 Unstable Zero

Common causes are:
1. Leak in pneumatic system.
2. Light leak - check the sensor module with strong light.
3. If equipped with IZS, zero air scrubber exhausted - replace charcoal and check broken DFU
filter.
4. Sample lines or sample filter dirty - clean or replace.
5. Zero gas source unstable - verify quality of zero air and the flow rate.

9.2.8 Inability to Span

If the SPAN button is not illuminated when attempting to span, that means the reading is
outside of the software gain ranges allowed . In an analog instrument it would be the equivalent
to the span pot hitting the maximum.
Here are some things to check:
1. Check the expected span concentration value in CAL-CONC, and compare this to the value
of the calibrator span gas being input. They should be close.
2. Check the PMT - TEST function. The value there should be about 2 x the expected span
concentration in step 1 above for range settings up to 2000 ppb in addition of the offset
value. If over 2000 ppb, the value should be about 0.2 x the expected span concentration in
addition of the offset value.
3. Check ET (see Section 9.1.3.2) and OT (see Section 9.1.3.3) for a response to 2000 mV on
the PMT - TEST function.
4. If the above do not check out, perform the Factory Calibration Procedure Section 9.1.6.
Analyzer Operator Manual, 02164, Rev. G
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