Teledyne 9110EH - Nitrogen Oxides Analyzer - Manual (Page 238)

Troubleshooting & Repair Model 9110EH Instruction Manual
Figure 1 -6: Pre-Amplifier Board Layout 1
• Adjust the HVPS fine adjustment such that the NORM PMT value is 800-830 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.
• If the NORM PMT value set above is now between 790-810, skip this step.
Otherwise, adjust the NORM PMT value with the gain potentiometer down to
800±10 mV (in general: 2x the span gas concentration value in ppb). This is the
final very-fine adjustment.
• 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.
• Perform a software span calibration (Section 7.2, 7.4, or7.5) to normalize the sensor
response to its new PMT sensitivity.
• 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).
224 M9110EH Rev 0