Maintenance
WFM 601A, WFM 601E, & WFM 601M Service Manual
6–27
Equipment Required.
The equipment needed to troubleshoot the Power Supply:
H
Digital Multimeter (DMM), with a diode check function
H
Oscilloscope
H
20 V
DC
Variable Power Supply
H
5 V
DC
Power Supply
H
High Voltage Probe,
1 G
W
input resistance
The Troubleshooting procedure for the Power Supply (Assembly A1) is in two
sections: the Low Volts Supply and High Volts Supply. Start the procedure by
isolating the problem to one of these two power supplies.
With the Power Supply installed in the instrument, apply AC power and press the
front-panel POWER switch until the POWER switch LED is lighted. From Table
6–3, determine which symptom the Power Supply exhibits and refer to the
corresponding procedure(s).
Table 6–3: Power supply fault symptoms
Symptom
Procedure
Line fuse open
Rectifier/Switcher/Snubber Check
Power Supply cycles OFF/ON
Note: Check instrument for shorts.
Output Check
Error Amplifier Check
Shut Down Logic Check
Does not power up
Controller/Gate Drive Check
Error Amplifier Check
Shut Down Logic Check
Rectifier/Switcher/Snubber Check
+5 V not regulating
Error Amplifier Check
Improper CRT display
High Volts Supply Checks
Troubleshooting the Low Volts Supply.
To troubleshoot the low voltage circuits on
the Power Supply board, follow these steps:
1. Preliminary Checks
a. A properly functioning and loaded Low Volts Supply will output the
voltages listed in Table 6–4. Use the DMM to measure the voltages
between TP1 (GND) and the voltage test points. Figure 5–5 on
page 5–15 shows the locations of these test points. If the supply is not
regulating properly, continue with the procedure to determine the
problem.
Summary of Contents for WFM 601A
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