Repairing 1997 Magnavox TV - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 7 Old 12-15-2019, 07:45 PM - Thread Starter
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Repairing 1997 Magnavox TV

I’d like to try and fix this. My 1997 Magnavox 19” 19PR14 no longer syncs to the input. It’s not a deflection issue as the OSD displays fine. I looked at the chassis board and reflowed a few suspect solder connections with the same result. I’m thinking there is either a sync amplifier that has gone bad or it’s the “jungle” video processor IC. I don’t think it’s the tuner as sound works fine. However, when changing from, say, channel 4 back to channel 3 the picture gets bright and dim 3 times before settling on rolling gray stripes. So could also be an AGC circuit getting confused.

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post #2 of 7 Old 12-21-2019, 12:09 PM - Thread Starter
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Bump.
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post #3 of 7 Old 01-08-2020, 11:56 AM
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post #4 of 7 Old 01-08-2020, 12:49 PM
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Dude, there's way newer and better freebies (or dirt cheap) out there. I'm staring at 2004 Sony WEGA 20" flat CRT that was thrown in with a 2006 RCA HD (yes, HD) 27" flat CRT with built-in ATSC tuner I picked up free on Craigslist. Also separately a 2004 Panasonic Tau 27" flat CRT and a Magnavox 20" flat CRT, both with built-in DVD players and VCRs.

Plus this forum is a ghost town...

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post #5 of 7 Old 01-08-2020, 01:30 PM
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Originally Posted by Chem1 View Post
Bump
Just curious. Why are you "bumping" someone else's thread?
Do you have the same TV and same problem?



If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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post #6 of 7 Old 01-08-2020, 03:51 PM
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Do you have the ability to safely replace components on the TV's mainboard? It is probably a dried electrolytic capacitor or two with as old as the TV is. I would start by following the advice of these two articles and replace the capacitors mentioned:


https://www.electronicspoint.com/for...c-issue.75887/


https://www.justanswer.com/tv-repair...-channels.html

My semi-dedicated theater: The EXASCALE CINEMA
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post #7 of 7 Old 01-12-2020, 04:21 PM - Thread Starter
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Originally Posted by AlienWarlock View Post
Do you have the ability to safely replace components on the TV's mainboard? It is probably a dried electrolytic capacitor or two with as old as the TV is. I would start by following the advice of these two articles and replace the capacitors mentioned:


https://www.electronicspoint.com/for...c-issue.75887/


https://www.justanswer.com/tv-repair...-channels.html
Thanks. Capacitors were my first thought. I am also looking at the data sheet for the Philips TDA8369 "jungle" video processor IC to try and trace where the composite sync comes in. In addition to that I tested various Motorola BC548C amplifiers in the jungle IC section for shorts and didn't find anything so far. I'm surprised to see Nichicon caps used exclusively in this otherwise cheap set with an RF only input though. That and the microprocessor IC is actually shielded.

While caps are the elephant in the room, I started off looking at the various amplifiers due to this video where the guy tracked down and replaced a bad sync amplifier. But I don't see this exact part on this chassis so I'm not thinking that's the issue at this point.

https://www.youtube.com/watch?v=_gQkzAlpAr0

Now that I have disassembled it and can take a closer look, I do see a large bulged cap in the high voltage section of the main CBA. As your links suggest, probably the B+ power supply filter cap for the regulator. It is a 200v cap with a smaller value (forgot and don't have it with me right now). Will definitely replace that one first and check.

Last edited by Titan91; 01-12-2020 at 04:56 PM.
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