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UPDATE: Great Mystery Magnavox TV 27MS3404/17 Problem



Jan 1, 1970

Thanks to everyone who offered their help.

I managed to get the TV to stay on, although I didn't find out what
actually was causing the shut down. I have Photofact 4968 for this model TV,
but there is no information about IC7200, TDA9577H. I couldn't find a data
sheet for this IC on the web. I suspect it relates to the beam current
sensing circuit or IC7200. Parts tested good and voltage measurements
were right on, or not far from values in Photofact.

I noticed if I increased the brightness with the pattern generator, the
TV starts to go off. I reduced (which were not set very high) the picture
settings such as brightness and picture/contrast, as well as the color level.
Then I increased the "screen" a small amount. Note: I had tried different
"screen" settings before, but that didn't fix the problem.

Now the picture is a pretty good (it was good before), and the TV stays on.
I ran it on and off for a number of hours.


Leonard Caillouet

Jan 1, 1970
These sets tend to have intermittent problems in the H drive circuit. There
is a kit avaialble torepair the problem, which usually becomes worse. Also,
the screen setting is critical and can cause shutdown.