RNOcommctr
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TV Tech Problem: Advice Needed

Fri Sep 08, 2006 12:32 am

I am getting a new TV today because of the following problem with my existing 27-inch Sharp tube-type set (15 years old but used very little). When I turn the TV on, just a thin horizontal line of picture appears. This condition remains for maybe 30 to 45 minutes before the full picture finally comes on.

I hate to trash the thing because it eventually gets a great picture. I would love to give the set to a charity or even a little mom-and-pop repair shop to fix it and sell it.

Anyone have idea what the problem might be and would it be feasible for someone to fix it?

Thanks.
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AsstChiefMark
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 1:00 am

After the TV has been unplugged for a few hours, remove the rear cover. Blow out all the dust with a can of that compressed air that's used to blow dust out of computers. Do a thorough job of cleaning the picture tube connections and high voltage board. Sometimes dust buildup can create small shorts that mimic larger problems. Often, once the dust is removed, the TV will work normally.

Mark
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oly720man
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 1:12 am

Beware that the high voltages can be lethal, so you may want to use some earthing strips to make sure any capacitors are fully discharged.

More than a few hours may be needed for self discharge. Our lab manager was rather unpleasantly surprised to still find high voltages on a tv more than a day after it was unplugged.
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KaiGywer
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 1:19 am

Quoting Oly720man (Reply 2):
Beware that the high voltages can be lethal, so you may want to use some earthing strips to make sure any capacitors are fully discharged.

More than a few hours may be needed for self discharge. Our lab manager was rather unpleasantly surprised to still find high voltages on a tv more than a day after it was unplugged.

Yeah, the best is to not touch anything in the TV, but rather use the compressed air. If you have to touch anything in the TV, use only one hand. That way, should you get zapped, the current will only go through your hand, and not your body (including heart).

If cleaning it doesn't work, I'm afraid the TV is probably not worth saving, as new TVs are so cheap these days.
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RNOcommctr
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 2:31 am

I am scared to death of electricity, so I will take all this advice very seriously. I'll give the thing a week to discharge and will just use the compressed air.

Thanks so much for the help.
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AeroWesty
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 2:39 am

While all the above is good advice, I have to wonder about something. In the past couple of decades, all TVs have been built with an "instant-on" feature that even when the TV is unplugged, will burn the equivalent of about a 25-watt bulb to keep the picture tube alive enough so we don't have to wait for it to warm up like in the olden days. Anyone remember waiting a minute or so for the old B&W consoles to come to life?

I wonder if this has anything to do with your problems.
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kmh1956
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 2:45 am

Quoting AeroWesty (Reply 5):
Anyone remember waiting a minute or so for the old B&W consoles to come to life?

Not only that, I remember the little white dot that appeared when you turned the set off and stayed for a good minute or so.
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richardnhsv
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 4:16 am

If this is what you mean...


It's called vertical collapse. Get a new TV..."fault with the vertical deflection circuitry. Many causes, dry joints, elecrolytic capacitors, vertical output , vertical oscillator etc."

Source: http://www.overclockers.com.au/wiki/TV_/_Monitor_/_Fault_Diagnosis
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RNOcommctr
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 5:13 am

Vertical collapse... that is what I do after about eight beers!

Yes, that is exactly what my old TV looks like. Thanks.
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HAWK21M
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 8:09 pm

Vertical hold defect.
If you know the circuitry there would be a Variable resister try tuning that with a Screwdriver.Else call the Expert.
Dont touch the Transformers/capicators.
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sprout5199
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RE: TV Tech Problem: Advice Needed

Fri Sep 08, 2006 10:15 pm

Quoting Oly720man (Reply 2):
More than a few hours may be needed for self discharge. Our lab manager was rather unpleasantly surprised to still find high voltages on a tv more than a day after it was unplugged

If the bleeder resistor is bad it will stay charged for a long time.

Quoting RNOcommctr (Reply 4):
I am scared to death of electricity, so I will take all this advice very seriously. I'll give the thing a week to discharge and will just use the compressed air.

If You have no electronic experience, then I would say DONT OPEN IT AT ALL. take it to a shop or buy a new one. I have been in electronics for 20 years(damn Im old) and I still hate working on crt's(cathode-ray tubes--tv's). have been bit by them too many times. 30kv sucks

Dan in Jupiter
 
RNOcommctr
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RE: TV Tech Problem: Advice Needed

Sat Sep 09, 2006 12:53 am

I went ahead and bought a 27-inch Sony flat-screen (CRT) last night. I am really happy with it... nothing fancy, but it has a great picture and is fine for the small amount of news and baseball I watch.

My buddy got at the same time a 34-inch Sony widescreen. It replaces a 36-inch Toshiba he had. The picture on the widescreen sure looks small compared to his old 36-inch, plus it appears flattened out. Anyway, we are both happy with our new sets although my back is feeling the effects of the effort last night.

The old TV you guys so kindly commented on yesterday goes to a charity and I will let their electronics expert tackle the problem. Thanks again for the help.
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