Thermo Scientific 42i Instruction Manual page 200

Servicing
PMT Voltage Adjustment
PMT Voltage
Adjustment
7-16 Model 42i Instruction Manual
6. To install the power supply, follow the previous steps in reverse.
7. Recalibrate the instrument. Refer to the calibration procedures in the
"Calibration" chapter.
Use the following procedure to adjust the PMT voltage after switching
from standard to extended ranges or vice versa.
WARNING The service procedures in this manual are restricted to qualified
service representatives.
1. Select the NO, NO
"Operation" chapter.
2. Set the NO BKG and NO
"Calibration Factors
3. Set the NO COEF, NO
4. Set the Averaging Time to 10 seconds. Refer to
the "Operation" chapter.
5. Connect the calibration gas and allow the instrument to sample
calibration gas until the reading stabilizes.
6. From the Main Menu, press
to scroll to PMT Voltage Adjustment > and press
The Set PMT Voltage screen appears.
Note If Service Mode is not displayed, refer to
Mode" on page 7-4, then return to the beginning of this step.
7. At the Set PMT Voltage screen, use
increment/decrement the counts until the instrument displays the
calibration gas concentration value.
▲
, and NO ranges. Refer to
2 x
BKG calibration factors to 0.0. Refer to
x
Menu" in the "Operation" chapter.
COEF, and NO
x
to scroll to Service > press
"Range Menu" in the
COEF to 1.000.
2
"Averaging Time" in
.
"Accessing the Service
▲
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