Teledyne 9110EH - Nitrogen Oxides Analyzer - Manual (Page 237)

Model 9110EH Instruction Manual Troubleshooting & Repair
• Attach the replacement dryer to the mounting bracket in the same orientation as the
old dryer. Fix the dryer to the bracket using new tie wraps. Cut off excess length of
the wraps.
• Put the assembly back into the chassis and tighten the mounting screws.
• Re-attach the tubes to vacuum manifold, flow meter and/or NO/NO
x
valve using at
least two wrenches and take extra care not to twist the dryer’s white plastic fittings,
as this will result in large leaks that are difficult to trouble-shoot and fix.
• Carry out a detailed leak check (Section 11.5.2), close the analyzer, power up pump
and analyzer and re-calibrate the instrument after it stabilizes
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.
• With the instrument running, set the instrument reporting range to SNGL (Section
6.5.3).
• Perform a full zero calibration using zero air (Section 7.2, 7.4, or7.5).
• Locate the preamplifier board (Figure 3-2).
• Locate the following components on the preamplifier board (Figure 11-6):
• HVPS coarse adjustment switch (Range 0-9, then A-F).
• HVPS fine adjustment switch (Range 0-9, then A-F).
• Gain adjustment potentiometer (Full scale is 10 turns).
• Turn the gain adjustment potentiometer 12 turns clockwise to its maximum setting.
• While feeding 400 ppb NO (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 NO, 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 just
above 800 mV NORM PMT signal (2x span gas ppb value). The coarse adjustment
typically increments the NORM PMT signal in 100-300 mV steps.
M9110EH Rev 0 223