Tektronix WFM601, Service Manual

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Maintenance
WFM 601 - Service Manual
6–7
WARNING. Read Instructions! Do not attempt to troubleshoot this Power Supply
without reading the following instructions.
This power supply presents special troubleshooting problems, if a fault occurs.
The Troubleshooting procedure that follows will help to isolate a problem to a
specific circuit. The circuit can then be analyzed to find the defective compo-
nent(s), or part substitution can be tried.
The equipment needed to troubleshoot the power supply:
H
Digital Multimeter (DMM), with a diode check function
H
Oscilloscope
H
20 Vdc Variable Power Supply
H
5 Vdc Power Supply
H
High Voltage Probe, 1 G input resistance
NOTE . Reading the power supply Theory of Operation is recommended before
attempting repairs.
The Troubleshooting Procedure for the Power Supply (Assembly A1) is split into
two sections, the Low Volts and High Volts Supplies. Start the procedure by
determining which section of the Power Supply the problem is in. With the
Power Supply installed in the instrument, apply ac power and turn on the
front-panel POWER switch. From Table NO TAG, determine which symptom
the Power Supply exhibits and refer to the corresponding procedure.
Table 6–2: 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
Shutdown Logic Check
Does not power up Controller/Gate Drive Check
Transformer Driver Check
Error Amplifier Check
Shutdown Logic Check
Rectifier/Switcher/Snubber Check
Troubleshooting
Procedure
Introduction