Model 100E Instruction Manual TROUBLESHOOTING & REPAIR
045150102 Rev XB1 221
Figure 11-4: Pre-Amplifier Board Layout
• Turn the gain adjustment potentiometer 12 turns clockwise to its maximum
setting.
• While feeding 400 ppb SO
2
(or 80% range value) to the analyzer and waiting until
the STABIL value is below 0.5 ppb, look at the front panel and scroll to the NORM
PMT value. This value should always be two times the span gas concentration in
ppb. With 400 ppb SO
2
, the NORM PMT should show 800 mV on a properly
calibrated analyzer.
• Set the HVPS coarse adjustment to its minimum setting (0). Set the HVPS fine
adjustment switch to its maximum setting (F).
• Set the HVPS coarse adjustment switch to the lowest setting that will give you
more than 800 mV NORM PMT signal. The coarse adjustment typically increments
the NORM PMT signal in 100-300 mV steps.
• Adjust the HVPS fine adjustment such that the NORM PMT value is just above 800
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. This can cause permanent damage to the PMT.
• Adjust the NORM PMT value with the gain potentiometer down to 800±10 mV. This
is the final very-fine adjustment.
To Next Page
Loading...
