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tv repair

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johnny69

New Member
i need some help, i have a sony trinitron 32 inch television and it's one of the older models and i was given it cause they were upgrading and i've had it for 6 months now probably and it's been working perfectly up till a couple days ago and then the color started going on the screen now theres patches on it where the color is messed up, like someones holding a magnet up to it, it's still watchable but i was just wondering if there is anthing i can do to fix the color, i know it has nothing to do with the dials to adjust color, i assume it has something to do with the tube, i was just wondering if anyone could help me with the problem.

thanks
 

johnny69

New Member
got a twang

when i turn it on i hear what could be considered a twang and then static on the screen as it turns on s oi assume thats what you mean
 

tunedwolf

Well-Known Member
I would say the degaussing circuit is up the kyber...

Replace the positor, the little three legged box prior to the mains bridge, the coil that goes round the tube is attached to it if you follow the circuit. Make sure the set is unplugged from the mains before doing anything, and be very careful of charged capacitors. It might be prudent to stick a 100K resistor, with insulated leads, across the main ones in the power supply for a few secs each before you do anything else, just to be sure they are discharged. A nasty crack from the main smoothing block can easily kill a smps or worse, not to mention give you a new hairdoo.
 

penoy_balut

New Member
avoid external magnetization, it can cause those color patches. you need a degaussing coil used by technicians to remove color patches, its stronger than the one in your tv
 

Nigel Goodwin

Super Moderator
Most Helpful Member
A VERY common problem on those Sony's is the scan coils sliding back on the CRT neck, often with the rubber wedges falling out as well - however I sugest you don't try and do it yourself as it's a fairly 'scary' procedure with plenty of places to get shocks from!.
 

HiTech

Well-Known Member
First, try using an external degaussing coil moved randomly across the CRT's face while you slowly pull it away several inches, finished by turning the coil perpindicular to the CRT. If the color blotches remain then I would suspect what Nigel mentioned. Often if the rubber wedges fall out or slip out of position you can return them to their exact spot by carefully examining the back of the CRT surface for a slight outline of where they were. Sparingly apply some quality contact glue to hold them in place.
 

audioguru

Well-Known Member
Most Helpful Member
Nigel Goodwin said:
A VERY common problem on those Sony's is the scan coils sliding back on the CRT neck, often with the rubber wedges falling out as well - however I sugest you don't try and do it yourself as it's a fairly 'scary' procedure with plenty of places to get shocks from!.
On my Sony 32" TV, the bottom 2 rubber wedges fell out and the other 2 are very loose. They seem to keep the scan coils from sliding too close to the CRT. What keeps the coils from sliding away from the CRT?
I didn't push very hard but the coils seem to be very secure.
 

tunedwolf

Well-Known Member
ooooh...lovely...a real live sony scan yoke in yer hands...
the static alone will frighten you as ya go near it...

The last one I done was about 6-7 years ago, and the damned anode cap fell out in the middle of the procedure...started jumping about arcing here and there etc....was frighteningly funny to watch according to my collegues...
The set survived, but I needed my purity adjusted afterwards...

I do agree though, loads of the sony's I have worked on suffered from purity problems due to the scan yoke moving about, it just didn't sound like it was this from what johnny69 posted.

Of course nobody mentioned that if he does play with the scan yoke, without a pattern generator, the tube set-up is unlikely ever to be close again. And in the case of a trinitron, a handful of those daft permalloy magnets won't go amiss either :)
 

audioguru

Well-Known Member
Most Helpful Member
tunedwolf said:
And in the case of a trinitron, a handful of those daft permalloy magnets won't go amiss either :)
Magnets?
My Trinitron has 2 self-adhesive 1cm square things (magnets?) stuck on the back of the CRT and 3 stuck on the holder for the scan coils. The holder for the scan coils has a very strong looking clamp that holds it secure.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
audioguru said:
Magnets?
My Trinitron has 2 self-adhesive 1cm square things (magnets?) stuck on the back of the CRT and 3 stuck on the holder for the scan coils. The holder for the scan coils has a very strong looking clamp that holds it secure.
OK, that 'very strong looking clamp' actually slides backwards and ruins the purity, often you can see the discolouration on the 'paper tape' wrapped around the CRT neck. Moving it back to there, and reinserting the wedges, is sometimes all you need to do?.

'Tunedwolf' - if a Sony anode cap came off it wasn't put on properly, they are a REALLY tight fit, with prongs that expand sideways to latch it in place. You can't get them off with out pressing the prongs together.
 

johnny69

New Member
degaussing

so i borrowed a degaussing ring from my electronics professor and took it home and tried it and it helped consideratly, theres just one small spot now along the top but i can definatly live with it compared to what it was like it's nothing, i was just wonderig if this could be a reoccuring problem or whether it was just something that happened to the tv, i guess it would be hard to tell though

thanks to everyone who replied to help me with my problem also, your help was greatly appreciated
 

tunedwolf

Well-Known Member
Yes Nigel, I'm aware of that. I was not however, aware that the set had already been somewhere else, before landing on my bench...
I have no idea why they would have had the anode cap off in the first place, but they didn't refit it properly, it was definately not clipped into place. Silly me for not checking it. Thank gawd, I'm no longer in the game, I guess 20+ years took it's toll...
 

HiTech

Well-Known Member
no big deal.... so you got to breath in a little ozone .... that should've have offset any negative feelings at the time!!!
 

a1batman

New Member
Did you find out if it was the positor that was faulty in the end? and if so where did you get a replacement from.
Regards from a1batman.
 

st_richard04

New Member
maybe that is also my problem...because my t.v. is totally no color at and return to the old black and white can anyone hepl me this problem....
 
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