25" Magnavox loses picture

Old 05-14-00, 02:45 PM
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My 25" Magnavox Model RS2555 loses its picture occassionally. When it does the only way to get it back is give it a smack on the side or jiggle the Coax Connector HARD!

I believe this was caused by my wife tripping over the cable coax a while back. I believe something was pulled loose (but not completely) on the inside of the unit, and I would like to try to repair it without taking it to a shop.

I am an A+ Certified PC Tech, so I feel confident in my electronics repair abilities,
but I want to make sure I discharge the electricity in the set before I start.

A few questions:

1) Do you think my hypothesis is correct?
2) Any direction on what to look for once I'm inside?
3) How can I protect myself while going inside?

Old 05-15-00, 07:50 AM
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A bad coaxial coupling could well be your problem and don't discount that it might be the external cable between the set and the wall.

When you remove the back from the set (and it is unplugged, of course), the only place for residual voltage to remain is on the picture tube, itself. You will see a rather large wire attached to the picture tube glass shell with a rubber cup. At this point, voltage may remain indefinitely (depeneding on the set)and the voltage may well be 25,000 - 45,000 volts. The picture tube acts much like the positive anode of an electrolytic capacitor. You can take a long screw driver with a ground clip to chassis ground, slide it under the rubber cup, and you will hear a momentary "snap" as the voltage arcs off.
Some sets have a very high resistance connected to this source and connected to ground. When the set is turned off, the voltage (and current) bleed off. So, if you do not hear the voltage arc to your screw driver. This may be the case.

As to what to check: The cable connection from the back of the set leads directly to the input to the channel selector (tuner).
This is where you would check for the intermittant connection.

Good luck.


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