General Maintenance
Table 4-4: Symptoms and causes (cont.)
Symptom Possible Sources or Recommended Detailed Troubleshooting Procedure to follow
Functional Test Failures
Performance VerificationTest
Failures
In case of failure o n e ither Functional or the Performance tests, the board at fault is generally
obvious. Before replacing a board:
1. Perform the p rimary and secondary power supply checks.
2. Run the advanced diagnostics and check the diagnostic log for help in isolating the fault.
If this does not isolate the problem, then replace the main board if the test is in one of the
following areas:
SDI
Composite
Ref
LTC
XGA output
Color Palette
Remote I/O
Ethernet
If the problem is only the SDI input, first replace the Mezzanine, Eye, or 3G board (depending
on option). If that does not fix the problem replace the main board.
If the problem is Composite, replace the composite option board. If the problem persists then
replace the main board.
If the problem is in the audio board, perform these tests:
1. Isolating Advanced Diagnostic Lissajous errors.
2. Audio Power-up Diagnostic Failure.
Unknown Problems
An instrument may come into
service with vague or intermittent
symptoms. In a case like this, the
following set of tests may help
find the problem or the marginal
condition.
1. Check the diagnostic log. This log records a variety of problems and will enable you to see
messages for an error that may not be currently happening.
2. Check the power supplies by performing the Primary and Secondary Supply checks. A
marginal supply can lead to intermittent operation if it is near the acceptable threshold. This
includes the m ain supply and the secondary supplies on each board.
3. Check the error log. This may give clues about how the unit w as operating when the user
saw problems.
4. Perform the incoming inspection tests. This will exercise a m ajority of the functions in the
unit and includes the advanced diagnostics. Some parts of the test may not be necessary
for all problem areas.
5. If the unit has an audio board, remove it and recheck any problem areas in the video
performance. The Audio board can place too much of a load on the supplies if they are marginal.
If the performance changes with the audio board removed, then you should perform the primary
and secondary power supply checks and look for an excess l oad on one of the supplies.
4–12 WFM6120, WFM7020, and WFM7120 Waveform Monitors Service Manual
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