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981
992
1002
1013
1023
1034
1044
1055
1065
1076
1086
1097
6.
A plot of the dark count and wavelength 1 intensity values vs the high voltage should be
compared to the plot in the Final Test Record.
The wavelength 1 data should exhibit a region of minimum slope (plateau).
The optimum setting for the high voltage is at the beginning of the plateau. The ratio is
determined by deviding the counts of wavelength 1 by the square root of the dark count.
If the new established optimum high voltage value deviates approximately 50 Volts or more
from the orignial setting then it is desired to change the current setting. See the HVSET
explanation on how to adjust the high voltage.
WARNING:
HVSET: Set PMT High Voltage
HVSET is used to set the PMT High Voltage as determined from the HV test.
This test requires access to the High voltage module and the front of the Main Electronics Circuit
Board.
Prior to starting the test, locate shorting plug J2 and potentiometer R4 on the High Voltage Module,
and test point E16 on the Main Electronics Board.
Method:
1. If not already done so, then turn off Brewer power and on the high voltage module move jumper
J2 from Pins 2-3 to Pins 1-2, and restore Brewer power.
2. Enter the HVSET command and enter the desired HV value at the prompt.
3. Measure the voltage at E16 on the Main Electronics PCB and write the value down.
4. Turn off Brewer power and set jumper J2 back to pins 2-3, and restore power.
5. Monitor E16 and adjust R4 on the High Voltage Module until E16 is set to the voltage as
recorded in step 3.
6. Confirm the setting with an AP command.
98
18
17
15
18
19
19
22
19
24
25
26
29
Changing the high voltage for the photomuliplier may effect the ozon
calibration, but will change the UV calibration for sure. The best time for
adjusting the high voltage is therefore during re-calibration of the Brewer
instrument.
MKIII OPERATOR'S MANUAL
APPENDIX F FACTORY TESTS
144932
34161
149962
36371
153943
39748
157825
37200
160926
36919
163407
37488
165796
35348
168082
38561
170292
34761
172626
34525
175036
34327
177199
32905
985.7
995.8
1007.8
1017.8
1027.8
1037.9
1049.9
1059.9
1069.9
1082.0
1092.0
1102.0
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