sonyowner
Joined: 22 May 2005
Posts: 2
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 22 May 2005 5:37 Sony KV32S40 video goes blank, Audio OK. need Help |
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I have a SONY KV32S40.
When I turn the TV on, works ok, and after a few minutes, the Video shrinks vertically and goes blank. the audio still OK.
I change channels in this mode, the channels change because I hear differnt channel's audio.
I found from some reading that that it is a fault in the Video-Out section of the main board. When the fault occurs in that section, the safety circuit kicks in and turns the video off. Opened the back cover, spotted the video-OUT area, tapped and moved some components, and found that a cap 220UF, 50V (C540), when wiggled during a vertical shrink, when moved, caused the picture to come Ok.
Thought there must be a loose connection, and may be a defective cap.
So got me a new 220UF, cap resoldered (with proper polarity) and the TV worked fine for about 8 hrs continuously, and a few hours the next day.
The TV is again acting the same way as before, and i am wondering if there are some tips some one can share.
Would greatly appreciate the help.
Thanks.
Sonyowner: trcengineer(at)yahoo.com
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jshroff
Joined: 30 Apr 2004
Posts: 116
Helped: 14
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29 May 2005 3:12 Re: Sony KV32S40 video goes blank, Audio OK. need Help |
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| You are on the right track this sounds like a bad solder joint in the vertical deflection circuitry, go over the vertical section specially around the deflection IC and the cap that you replaced. resolder all the joints, if that does not help start tapping around the vertical sections and the spots where the V deflection start worsening focus on resoldering in those sections.
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sonyowner
Joined: 22 May 2005
Posts: 2
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30 May 2005 17:33 Re: Sony KV32S40 video goes blank, Audio OK. need Help |
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This weekend, I resoldered the 7 pin IC (the one that has a huge heat sink) again.
I couldn't find my magnifying glasses to check the joints. Soldered again with some good glob of solder.
Since then it has worked sat, sunday and this morning. I am told that this IC gets hot, and I am wondering if heat is not getting dissipated good enough with the back cover etc. installed. I have access to a laser beam temperature reader at work. I am going to aim it on the IC, and different swctions of the heat sink to profile the temperature gradient with passage of time with TV turned on. If I see some temp higher than 85C, I am going to stick a 12V fan near the openings on the back cover to get the heat out.
So far it works OK and I am a happy camper.
Thanks for the input and the support from the forum.
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