Tektronix WFM601, Service Manual

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Maintenance
WFM 601 - Service Manual
6–5
Corrective Maintenance
The following procedure is designed to assist in isolating problems, which in
turn expedites repairs and minimizes down time.
1. Ensure that the malfunction exists in the instrument. This is done by making
sure that the instrument is operating as intended by Tektronix (see Operating
Instructions), and by checking that a malfunction has not occurred up stream
from the waveform monitor.
2. Determine and evaluate all trouble symptoms. This is accomplished by
isolating the problem to a general area such as an assembly. The block
diagram is a valuable aid in signal tracing and circuit isolation.
CAUTION. Use extreme care when probing with meter leads or probes, because of
the high component density and limited access within the instrument. The
inadvertent movement of leads or a probe could cause a short circuit or transient
voltages capable of destroying components.
3. Determine the nature of the problem. Attempt to make the determination of
whether the instrument is out of calibration or if there has been a component
failure. Once the type of failure has been determined, proceed on to identify
the functional area most likely at fault.
4. Visually inspect the suspect assembly for obvious defects. Most commonly
these will be broken or loose components, improperly seated components,
overheated or burned components, chafed insulation, etc. Repair or replace
all obvious defects.
5. Use successive electrical checks to locate the source of the problem. The
primary tool for problem isolation is the oscilloscope. Use the Performance
Check Procedure to determine if a circuit is operating within specifications.
At times it may be necessary to change a calibration adjustment to determine
if a circuit is operational, but since this can destroy instrument calibration,
care should be exercised. Before changing an adjustment, note its position
so that it can be returned to its original setting.
6. Determine the extent of the repair. If the necessary repair is complex, it may
be advisable to contact your local Tektronix field office or representative
before continuing. If the repair is minor, such as replacing a component, see
the parts list for replacement information. Removal and replacement
procedures for the assemblies can be found under Corrective Maintenance.
General Troubleshooting
Techniques