The following applies if the part of the picture is missing but not
otherwise squashed or distorted. For example, 85% is missing but the
portion still visible is normal size.
|NotTaR of Television Sets : Part of picture cut off
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<< Vertical squashed |
Wow! That's an interesting one, more so than the typical run-of-the-mill
"my TV just up and died on me". Or, "my pet orangutan just put a hole
in the CRT, what should I do"?
Since the size of the picture fragment is correct but 85% is missing,
my first thought would be to check waveforms going into the vertical
output stage. The supply voltage is probably correct since that often
determines the size. It almost sounds like the waveform rather than
being mostly on (active video) and off for the short blanking period
is somehow only on during the last part of the active video thus giving
you just the bottom of the picture. If there is a vertical output IC,
it may be defective or the blanking input to it may be corrupted. The
problem may be as far back as the sync separator. Then again who knows,
maybe wait for the schematics.