2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
114
3.7.2.1 Electron Multiplier High-Voltage Supply Test
1 Remove instrument power, and wait one minute for the A16 module voltages
to bleed down.
2 Re-connect the Ion Pump high-voltage supply cable to A17.
3 Disconnect the left-hand high-voltage lead and reconnect it to the tip of the
high-voltage probe using a short piece of insulated wire between the inside of
the high-voltage lead connector and the
high-voltage probe.
4 Ground the high voltage probe return to the 5071A chassis, and plug the
probe output into the DMM. Set voltage mode and at least 10.0 Volts range.
The input impedance of the DMM must equal that specified for the high-
voltage probe.
5 Apply instrument power, wait for the instrument to begin warming up, and
observe the voltage displayed by the DMM. Multiply this voltage by the
voltage-division ratio of the probe and record results.
6 Observe the voltage displayed on the LCD using the INFO/EMULT menu
selection. Note that the LCD does not display the sign of the voltage.
QUESTION: Do the voltage readings agree to within 5%?
If Yes: The A16 High-Voltage Supply Module is functional. Remove
the extender, replace A2. Re-connect A19 to A1 at A1J11, and
reconnect the semi-rigid cable from the SMA connector on A19
to A9J5. Continue testing.
If No: Go to, 3.7.2.2.