TV Picture Symptom

It sounds like there are some components that have become thermo sensitive from age. Most of the time, this is caused by capacitors going high in ESR.

To service your set, you will need to have TV service training, a good knowledge of electronics, and the tools to troubleshoot and service the set. There are serious safety issues when working on TV sets.

I would suggest taking the TV in for an estimate for repairs. I am sure that the previous owner is replacing the TV for obvious reasons rather than having it serviced.

Jerry G. ======

if the picture is squashed vertically i.e a gap at the top or bottom of the screeen chances are its capacitors in the vertical/frame output stage. That is fixable.however this is pure guesswork, we don't have much to go on!

when you pick it up, we will need a picture of the screen to get a better idea..

-B

Thanks guys. I will see if I can still score it and get back to you.

Jerry - I am well advised on the dangers of working on TVs. It's been 20+ years, but I took electronics in vocational technical school, and have been reading a lot about the repair of classic arcade games.

Regardless, I sincerely appreciate the advice that you gave, and the concern that drove you to give it.

Stay tuned.

Bad capacitors in the vertical section, you don't really need any special tools, just replace all the suspects, it'll only cost a few dollars. This is a good candidate for a beginner learning to repair TVs.

Agreed. But make sure you understand and follow the SAFETY guidelines.

Service information will also help to identify the suspect parts. Your local large public library may get the Sams' Photofacts.

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Would the same apply if there were *no* picture (apart from menu items) for the first five minutes while the set warms up? This is the problem I'm having with one of mine.

Beginner in what, TV repair? From what I read between the lines this guy is your average Joe that knows how to solder to some degree looking for a cheapo TV and not looking to start repairing them. He's going to need to know all the safety precautions, how to identify parts, where the vertical components are located, etc...etc... This is a lot of hand holding and not really a viable repair via Usenet considering all of the above. Don't get me wrong I'm all for the newbie willing to learn these things but I don't think it applies to someone who has no idea whatsoever what he's doing.

If you are very careful, you can narrow your search area by using a heat gun on the capacitors and it will be obvious which capacitor is at fault. Since this requires operating the TV with the back off, do not do this unless you are very careful and have set up an access scheme where you can get to the capacitors and see the screen and not have to touch anything while the power is on. Also be careful of the high voltage on the crt which will be there even on power off. If you are not careful with the heat gun, you will have more parts to replace than when you started. A hair dryer may also work and have fewer opportunities for mischief. I did this on a TV a few years ago and the culprit was a small 10uf cap. It has worked fine for ever since.

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How exactly will it be obvious?

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If the picture is restored to normal when the set heats up, heating the failing capacitor will restore the picture height. Conversely, cooling it will make the picture shrink. In my TV, it was pretty dramatic. In my case, the capacitor, while part of the vertical circuit, was in another place on the board so doing a general replacement of the vertical capacitors would probably had me missing this one. Also, searching on the web for this got useful hits about others having the same problem. This way took less than an hour including dealing with the case. The bad capacitor had a big effect on the picture but none of the others did much of anything. First isolate the problem to a large area and then block off enough of the hot air output to localize the individual capacitor.

Maybe, but if it's a Sony set, it's probably the AKB circuit blanking the pucture because the CRT is weak.

A lot of people on this group are quick to assume that everyone inexperienced is an idiot and has no hope. Yes there's some safety issues, though as a practical matter this applies more to the implosion hazard of the CRT than high voltages, don't touch anything in the set with your hand while it's plugged in, unplugged a modern TV will discharge itself within moments in most cases. I've stepped a lot of novices through repairing arcade game monitors, and a TV is really no different.

Read Sam's FAQ and get out a hair dryer and some freeze spray (a can of air duster held upside down works just as well) and go for it.

Please note that nowhere in my reply did I say or imply the OP was a hopeless idiot.

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Interesting. But presumably this method only works for warm-up problems and cannot be adapted to failing capacitors in general?

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It is a bit more general than that but is not universal. If a part has completely failed, heating or cooling do not change how it works. But failing parts often change characteristics when heated. Heat guns and freeze mist have long been used for this kind of troubleshooting. It just means you should start troubleshooting when things first start going bad rather than waiting until you have a complete failure.

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It is generally understood that in some cases warming a capacitor will restore its function enough to remove whatever fault it created in a circuit. This is the theory that some of us have based our diagnosis of your set upon. If correct you could purposely heat that capacitor up while the vertical problem was manifested and within seconds, not minutes the vertical would resume to normal size. Same goes that you could cool the capacitor and watch the vertical shrink.

Semiconductors behave similarly but in opposite. Cooling a noisy or leaky semiconductor (not shorted or burned open) in some instances can make them operate normally until they warm. I've been using these trouble shooting techniques for many years.