2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
115
3.7.2.2 Electron Multiplier Supply Control Current Test
1 Remove instrument power, and wait one minute for the A16 module voltages
to bleed down.
2 Power up and check that the instrument enters the warming up mode in
about 10 seconds.
3 Verify that the green LED A2DS1 is lit.
4 Use the DMM to measure the current from A2U7-pin-3 to ground.
5 Use the INFO/E_mult Menu to display the program voltage of the Electron-
multiplier supply.
6 Verify the ratio of displayed voltage to measured current as between 950 to
1050 volts per mA.
(Ratio = displayed voltage measured current)
QUESTION: Is the ratio of displayed volts to measured mA correct?
If Yes: A2 is delivering the correct control current. Remove power,
replace A16, and re-test.
If No: Remove power, replace A2, and re-test.
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