No picture And only centre 3rd of screen, shuts off automatically
Sony Kv T29SF81
when You turn It on screen Shrinks and gets smaller until only centre 3rd of screen remains and then Shuts off.
Took back off and adjusted the one of the KNobs/pots and managed to stop screen from shutting off but only get centre 3rd of screen and its green
thinking it may be a faulty power supply. have checked main board and cant find any dry joints. I am an electrician but im completely lost and i have no knowledghe on tvs
can you help
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Re: No picture And only centre 3rd of screen, shuts off...
It a problem in the vertical sweep circuit my freind. It could be the vertical IC, a capacitor thats bad the B+ sweep supply, or a bad connection on the board, but my moneys on the first, a bad vertical output IC. if you lug the thing into a repair shop it should not cost you over 125 to 150 bucks. if you have solid state serviceing as well as soldering experience you can get a service manual and find the vertical output IC and replace it. You stated you had no electronic experience on TV sets? Play it safe and let a pro assist you with this repair. Good Luck
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Movies are shown at a higher resolution than games. That is why the picture is smaller with games than movies. If you turn the Auto Picture Size off, you can set lower grade video to a larger screen size but you will lose quality. Hope that helps.
you have to turn the screen control up a bit.there are 2 conrols on the flyback transformer,top one is focas bottom one is screen,turn it up 1/8 turn turn set off then on.repeat this until picture appears(if you turn it up too much picture will be to brite with lines and will shut off) if it shuts off just turn contron down a bit then restart it.
Since the set works initially, there are likely poor solder connections at the vertical IC. If this is not addressed soon, the IC will fail and need to be replaced. The vertical IC is a small flat IC with about 11 pins or so that may be marked LA7837 or something similar. Try resoldering the pins first. If that fails to resolve the problem, replace teh IC. Feel free to post the marking here so I can verify you have the correct one.
In electronics dust has nothing to do.
cleaning will not solve your problem
your problem is due to trouble in vertical section.
mostly it is due to electrolytic capacitor in vertical section is defective.it is common problem.
also check supply to vertical section.
"THE SCREEN SHRINKS TOWARDS THE TOP OF THE SCREEN FOR A FEW SECONDS BEFORE THE PICTURE TURNS UPSIDEDOWN THEN TURNS BLACK." is called fold over.
Yes, you are correct. Usually what I find in a set like that with that symptom is that the solder joints have cracked and come loose on the vertical output IC. That is the IC which drives the yoke coils that spread the picture up and down. If you have soldering experience then you can locate this IC and resolder its pins but if you have never worked on PC boards then have a qualified tech handle it for you. This is a very easy thing to repair so it should not cost too much.
You have a bad solder connection in the vertical circuit. This will require you to resolder these bad connections before it blows out the vertical output IC or other parts in the circuit. Do this ASAP before you make a small repair into a large one. If you have no solid state printed circuit board experience, please play it safe and take the set into a pro to do this for you. Good Luck