Teledyne API - Model T200H/T200M Operation Manual
Troubleshooting & Service
257
9. Set the HVPS coarse adjustment switch to the lowest setting that will give you just
above 3600 mV
NORM PMT
signal. The coarse adjustment typically increments
the NORM PMT signal in 100-300 mV steps.
Figure 7-17:
Pre-Amplifier Board Layout
10. Adjust the HVPS fine adjustment such that the
NORM PMT
value is 3600-3700 mV.
The fine adjustment typically increments the
NORM PMT
value by about 30 mV.
It may be necessary to go back and forth between coarse and fine adjustments if the
proper value is at the threshold of the min/max coarse setting.
Note
Do not overload the PMT by accidentally setting both adjustment switches to
their maximum setting. Start at the lowest setting and increment slowly. Wait
10 seconds between adjustments.
11. If the
NORM PMT
value set above is now between 3560-3640 mV, skip this step.
Otherwise, adjust the
NORM PMT
value with the gain potentiometer down to
3600±10 mV.
This is the final very-fine adjustment.
12. Note that during adjustments, the
NORM PMT
value may be fluctuating, as the
analyzer continues to switch between NO and NO
X
streams as well as between
measure and AutoZero modes.
You may have to mentally average the values of NO and NO
X
response for this
adjustment.
13. Perform a software span calibration (Section 5.3, 7.4, or 7.6) to normalize the
sensor response to its new PMT sensitivity.
14. Review the slope and offset values, the slopes should be 1.000±0.300 and the
offset values should be 0.0±20 mV (-20 to +150 mV is allowed).
07270D DCN7141