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 Post subject: You TV-type guys can explain?
PostPosted: Dec Fri 07, 2012 12:46 am 
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I have a 13" Sansui TvM1316E - color TV in the bedroom. It's about 5-8 years old or more.
Recently when I 1st turn it on it exhibits a pattern of about 10 white retrace lines at the top of the screen going down about an inch or 2
This slowly shrinks to less than an inch and eventually goes away after about 5 minutes.
What's up?

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 Post subject: Re: You TV-type guys can explain?
PostPosted: Dec Fri 07, 2012 12:55 am 
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Most likely it is a failing capacitor in the vertical section. If you want to fix it, get an ESR meter and start checking the electrolytics.

-Matthew

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 Post subject: Re: You TV-type guys can explain?
PostPosted: Dec Fri 07, 2012 3:44 am 
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As was mentioned, the retrace lines are a clue that the pump-up capacitor is starting to fail.
Continued use of the set will most likely take out the vertical IC chip as well.
Best to replace the cap, and also re-solder all pins on the chip, as they're probably overheated from the stress.

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 Post subject: Re: You TV-type guys can explain?
PostPosted: Dec Fri 07, 2012 10:07 am 
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RepairTech wrote:
As was mentioned, the retrace lines are a clue that the pump-up capacitor is starting to fail.
Continued use of the set will most likely take out the vertical IC chip as well.
Best to replace the cap, and also re-solder all pins on the chip, as they're probably overheated from the stress.

I know nada about TV... what is the chip type-number I'd be looking for. Would that cap be close-by?
Do you think it will be easy to see by swelling or bulging on top?

Does anyone have a schematic?

Do you think it's going to be easy enough to disassemble it so as to actually have reasonable physical access to that section and board?

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 Post subject: Re: You TV-type guys can explain?
PostPosted: Dec Fri 07, 2012 11:31 am 
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Sansui made a TV?

I suggest replacing all the electrolytics around that vertical IC; use the same values. Also, many of those TVs got B+ from the flyback--look for bulging or leaking caps around the horizontal output transformer.


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 Post subject: Re: You TV-type guys can explain?
PostPosted: Dec Fri 07, 2012 2:42 pm 
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Peter,
Well don't get affraid of thoses tv's the vertical circuit is just a audio amp instead of a speaker hooked to the audio output ic chip it's has a yoke .
I't a very simple circuit design if you just break down the tv's circuit's when dealing with them .
sincerely Rich


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 Post subject: Re: You TV-type guys can explain?
PostPosted: Dec Fri 07, 2012 4:43 pm 
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Pbpix wrote:
RepairTech wrote:
As was mentioned, the retrace lines are a clue that the pump-up capacitor is starting to fail.
Continued use of the set will most likely take out the vertical IC chip as well.
Best to replace the cap, and also re-solder all pins on the chip, as they're probably overheated from the stress.

I know nada about TV... what is the chip type-number I'd be looking for. Would that cap be close-by?
Do you think it will be easy to see by swelling or bulging on top?

Does anyone have a schematic?

Do you think it's going to be easy enough to disassemble it so as to actually have reasonable physical access to that section and board?



The myriad (I love that word) of sets being out there, I cannot know the exact IC part number of any specific set.
However, the vertical IC in question would be mounted on a heatsink - probably have 7-12 pins sticking down into the PC board. - located near the big flyback transformer or yoke plug - capacitors right near it (the IC) might be marked 100uf, or 220uf... should show no signs of being bad, just replace them, observing polarity.
The IC chip might be marked LAxxxx, or TAxxxx.

A good idea is to go over the board and carefully touch up any "iffy" solder connections - stuff mounted on heatsinks, the flyback, etc.
Look for discolored areas of the board due to heat, and use a magnifying glass to check for cracks in solder.

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 Post subject: Re: You TV-type guys can explain?
PostPosted: Dec Fri 07, 2012 4:52 pm 
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Pbpix
vertical output IC's are typically in a single in line package, usually mounted to a small heatsink.
like this one...http://db.tt/RfE7i0EM
So look for a package like that. I think the Caps ur interested in should be nearby.
Sometimes there may be printing on the PC Board as to which area of the board is which (Vert, Audio, Horiz, etc).
Probably not as common as it used to be when sets used more discrete componenents.

here's a link to datasheet for the one above. Which may give ya some insight on the circuit in question.
http://www.electronica-pt.com/ci/LA7837-LA7838.pdf


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 Post subject: Re: You TV-type guys can explain?
PostPosted: Dec Sat 08, 2012 12:39 am 
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Thanks for all the addition input.
Maybe I'll venture inside the cabinet this week end.. but I'm a little aprhensive because often these things are so tightly fit together that trying to get at something ends up destroying somethinbg else and you never get the thing back together again.. lol

BTW:
I wrote to Sansui asking about a schematic. What a joke!
Here's the reply:

Thank you for contacting Orion Sales, Inc.
Schematics are not available to the public.
I can refer you to a service center if you like.
Elaine

Customer Service Admin.

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