General Maintenance
Cable Loss, App
rox Cable, and Source Level Readout Problems. These
measurements are made by a “cable meter” circuit. This circuit is loc ated on
the EYE board, but is largely independent from the Eye and Jitter display and
measurement functions. If other EYE/PHY functions operate correctly, then a
“cable meter” circuit problem is indicated. Replace the EYE/PHY board.
Jitter Readout and Jitter Meter Problems. These measurements are derived from
sampled recovered clock sine wave data. Operation is unlikely to fail if the basic
Eye pattern display works correctly. Measurement accuracy is not adjustable, but
jitter noise floor depends on adjustment of Eye HD CDR calibration items.
Eye Amplitude, Eye Risetime, Eye Falltime, and Eye Rise-Fall (difference) Readout
Problems. These readouts are only available with Option PHY. These readouts
are derived from the Eye pattern display. Measurement accuracy depends on the
Eye Gain calibration items, and on front-end bandwidth and transient response,
which are not adjustable. Operation is unlikely to fail if the basic Eye pattern
display works correctly.
It is normal for these measurements to stop or become intermittent if there is
excessive waveform noise, aberrations, jitter, or cable loss.
Option 3G/JIT
Troubleshooting
The 3G/JIT functions depend on the 3G and Main boards and the interconnections
between them.
Major Operational or Diagnostic Failure.
Check that the 110 pin CPCI connector between the 3G and Main boards
is correctly seated and undamaged.
Check that the ribbon cable from the 3G board to the Main board is securely
plugged into J5 on the 3G board and J16 on the Main board.
Basic SD or HD Operation Problems. For SD (270 Mbps) and HD (1.5 Gbps)
signals, the signal path to the Main board is short and direct. The problem may be
on either the 3G board or the Main board. If SDI OUT fails when configured for
Loop Out A or B, then replace the option 3G board. If available, a Mezzanine
board may be installed in place of the 3G board for troubleshooting purposes to
verify basic SD/HD operation of the Main board.
Basic 3 Gbps Operation Problems. If using an independent 3 Gbps source, check
that the SDI Output is not configured for Loop Out Test Signal. If basic SD (or
optional HD) operation is good on both SDI A and SDI B inputs but 3 Gbps
operation fails, then replace the option 3G board.
Jitter Waveform Display Problems. Jitter Waveform display for 3 G bps signals is
available only with option JIT. The jitter waveform is derived from the sampled
recovered clock sine wave.
4–22 WFM6120, WFM7020, and WFM7120 Waveform Monitors Service Manual
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