2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
112
QUESTION: Is the measured voltage when multiplied by the high
voltage probe calibration factor between 3.3 kV and 4.3
kV?
If Yes: Go to, 3.7.1.2
If No: Remove power, replace A16 and retest.
3.7.1.2 Ion Pump Return Current Test
1 Use the INFO/PUMP menu selection to display the output of the Ion Pump
current monitor circuit.
QUESTION: Was the current displayed between 3 and 5 microamps?
(The high-voltage probe must have an input resistance of 1
Giga.)
If Yes: Go to 3.7.1.3.
If No: Go to 3.7.1.3.1.
3.7.1.3 Ion Pump Return Current Zero Test
1 Power down the instrument, and wait one minute for the A16 module voltages
to bleed down.
2 Disconnect the Ion Pump supply cable from the high-voltage probe and
locate the plug well clear of other conductors.
3 Re-power the instrument, wait 15 seconds, and use the INFO/PUMP menu
selection to display the Output of the Ion Pump current monitor circuit on the
LCD display.
QUESTION: Is the displayed current between 0.0 and 1.0 microamps?
If Yes: Ion Pump high-voltage supply is correct, Go to, 3.7.2.1.
If No: Go to 3.7.1.3.1.
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