Filter
Top Products
Troubleshooting & Repair Teledyne API - Model 200EH/EM Operation Manual
270
11.6.5. PMT SENSOR HARDWARE CALIBRATION
The sensor module hardware calibration is used in the factory to adjust the slope and offset of the PMT output
and to optimize the signal output and HVPS. If the instrument’s slope and offset values are outside of the
acceptable range and all other more obvious causes for this problem have been eliminated, the hardware
calibration can be used to adjust the sensor as has been done in the factory. This procedure is also
recommended after replacing the PMT or the preamplifier board.
1. Perform a full zero calibration using zero air (Section 7.2, 7.4, or 7.6).
2.
Locate the preamplifier board (Figure 3-1).
3. Locate the following com
ponents on the preamplifier b
oard (Figure 11-):
HVPS coarse adjustment switch (Range 0-9, then A-F).
HVPS fine adjustment swit
ch (Range 0-9, then A-F).
Gain adjustment potentiometer (Full scale is 10 turns).
4. Turn the gain adjustment potentiometer 12 turns clockwise to its maximum setting.
5. Feed NO to the analyzer:
For the M200EH use 450 ppm NO.
For the M200Em use 18 ppm NO.
6. Wait until the
STABIL value is below 0.5 ppm
7. Scroll to the
NORM PMT value on the analyzer’s front panel.
8. With the NO gas concentrations mentioned instep 5 above, the
NORM PMT value should be 3600 mV.
9. Set the HVPS coarse adjustment to its minimum setting (0). Set the HVPS fine adjustment switch to its
maximum setting (F).
10. 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 11-22: Pre-Amplifier Board Layout
04521C (DCN5731)