Teledyne 9110T - Nitrogen Oxides Analyzer - Manual (Page 312)

Model 9110T NOx Analyzer Troubleshooting & Service
Teledyne Analytical Instruments 312
slowly. Wait 10 seconds between adjustments.
Note During these adjustments, the NORM PMT value will fluctuate as the
analyzer continues to switch between NO and NOx streams as well as
between measure and Auto Zero modes.
13. Perform a span point calibration (see Section 9) to normalize the sensor response
to its new PMT sensitivity.
14. Review the slope and offset values:
 The slope values should be 1.000±0.300.
 The offset values should be approximately 0.0 (-20 to +150 mV is allowed).
12.8.5. REPLACING THE PMT, HVPS OR TEC
The photo multiplier tube (PMT) should last for the lifetime of the analyzer, however, the high voltage
power supply (HVPS) or the thermo-electric cooler (TEC) components may fail. Replacing any of these
components requires opening the sensor module. This is a delicate assembly and it is recommend that
you ensure the PMT, HVPS or TEC modules are, indeed, faulty before unnecessarily opening of the
module.
C
AUTION
Q UALIFIED P ERSONNEL
While the PMT or HVPS can be removed through the front panel without un-
mounting the entire sensor module, we recommend turning off the instrument,
opening its top cover and removing the entire assembly so that further repairs can
be carried out at an anti-ESD workstation.
Follow the guidelines defined in Section14for preventing electrostatic damage to
electronic components.
1. Turn OFF the analyzer and disconnect the power cord.
2. Remove the cover.
3. Disconnect all pneumatic and electrical connections from the sensor assembly.
4. Remove the sensor assembly.
5. If the TEC is to be replaced, remove the reaction cell assembly at this point by
unscrewing two holding screws.
 This is necessary only if the repair being performed involves removing the PMT
cold block.