Kipp&Zonen Brewer MkIII User Manual

Page 101

MKIII OPERATOR'S MANUAL

981 18 144932 34161 985.7
992 17 149962 36371 995.8
1002 15 153943 39748 1007.8
1013 18 157825 37200 1017.8
1023 19 160926 36919 1027.8
1034 19 163407 37488 1037.9
1044 22 165796 35348 1049.9
1055 19 168082 38561 1059.9
1065 24 170292 34761 1069.9
1076 25 172626 34525 1082.0
1086 26 175036 34327 1092.0
1097 29 177199 32905 1102.0

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: 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.

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.

APPENDIX F FACTORY TESTS