Video and/or Power problem - Suggestions please!

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Silvester
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Re: Video and/or Power problem - Suggestions please!

Post by Silvester »

Looks like the VP12 line is being ground by UHF can (top track in image under M1 legend).
VP12track.JPG
Though I don't understand why IC28 would overheat :?


David
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Pr0f
QL Wafer Drive
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Re: Video and/or Power problem - Suggestions please!

Post by Pr0f »

Silvester wrote:Looks like the VP12 line is being ground by UHF can (top track in image under M1 legend).
VP12track.JPG
Though I don't understand why IC28 would overheat :?
12v is used by the video colour encoder chip - 1377


Silvester
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Joined: Thu Dec 12, 2013 10:14 am
Location: UK

Re: Video and/or Power problem - Suggestions please!

Post by Silvester »

Pr0f wrote:
Silvester wrote:Looks like the VP12 line is being ground by UHF can (top track in image under M1 legend).
VP12track.JPG
Though I don't understand why IC28 would overheat :?
12v is used by the video colour encoder chip - 1377
Yes, but I don't understand how shorting +12V to ground (if that is what happened) would cause IC28 to overheat.


David
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Harbars
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Re: Video and/or Power problem - Suggestions please!

Post by Harbars »

I did have a poke around to see what might actually be interfering - it's actually the bottom of the can pressing down (component side) but it wasn't at all obvious. I've placed a strip of plasticard under that edge of the can for now. I'd imagine finding out for sure would involve removing the can - not sure I can be bothered with that, and am now away for a few weeks. As long as it works I'm happy although I'd still like to get to the bottom of it.


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