[Coco] Help: Magnavox 1CM135 Monitor
robert.gault at worldnet.att.net
Sun Feb 29 23:18:20 EST 2004
Boisy G. Pitre wrote:
> I have a Magnavox 1CM135 RGB/Composite Monitor - this thing was working
> great, then all of a sudden stopped. Now there is no picture. Just a
> constant, high pitch squeal when you apply power.
> Can any of you Monitor guys (Gene Heskett?) provide some insight as to
> what possibly may be wrong? I don't have much expertise on diagnosing
> monitors, and before I pitch it to the curb, I want to make sure it
> isn't something simple or easy to fix.
If you hear it as a "high pitched squeal", it pretty much has to be the
15KHz circuit. The transformer could be heard if the plates have gotten
loosened on set like this but that normally did not prevent it from working.
Most likely thing is a blown output transistor in the horizontal
circuit. However, without a circuit diagram including voltage points and
wave forms, it is going to be difficult to diagnose your set. You will
probably need an oscilliscope and educated guessing at the type of
waveforms that should be present within the horizontal circuit. Back
track from the output transistor until you find a waveform. The
transistor that separates the waveform from the blank portion should be
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