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post #1 of 4 Old 07-28-2010, 10:44 AM Thread Starter
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Old (1990s era) big screen TV problems

I have a 1990s era 40" Mitsubishi rear projection TV-you know-the gigantic ones with the "textured" plastic screens, giant speaker at the base, and wood paneling on the sides. It was a Craigslist freebie and despite the fact that it's not one of them new fangled "flat panel" TVs, we love it and would like to keep it humming along for many years. Recently it has developed the following problem:

When you first turn it on sometimes you'll get either a totally black screen or a scrambled screen (a little like the way the premium channels used to look on cable if you didn't have a subscription to them), but the sound is unaffected. Smacking the top brings the picture into focus, and once it focuses it rarely goes back to the scrambled state as long as the set is left on. Does anyone know if this is a simple problem? If I could fix this for $200 or less I'd gladly do it since it would be a heck of a lot cheaper than buying a new TV!

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post #2 of 4 Old 07-28-2010, 11:49 AM
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Re: Old (1990s era) big screen TV problems

Before I'd waste $200 on fixing a CRT projection TV, I'd watch Shop NBC when they have the 72" Mitsubishi DLP deal for $1300 delivered.....

Fixing CRT projection sets can get real expensive, real quick.. especially if the tubes are going south (7 to 9" tubes at $300 each if you can find them). Lots of high powered control boards, probably years of smoke/dirt on the optics...

Best thing you can do is have a repairman look at it (which will cost money) then determine what's wrong with it... And pay more money.

I'd buy a DLP! (In fact, that's exactly what I did).

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post #3 of 4 Old 07-28-2010, 03:32 PM
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Re: Old (1990s era) big screen TV problems

It's likely the high voltage. Those sets use an interlocked HV system that won't allow the scan to come up unless they're within the proper range. This is for safety because those tubes are projection tubes.

By banging on it, you're moving around some connectors and probably hitting a cleaner spot. That's the first thing I would look for, dirty connectors. Clean with tuner tonic and reassemble. Also, banging on it is not advised; if you knock the physical alignment of the projection tubes out, it's a long process to get them realigned.

But I would be careful in monkeying with it; the anode voltages run to about 130 KV (130,000 volts). The HV boards are replaceable as a unit - IF you can find a replacement.


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post #4 of 4 Old 07-28-2010, 07:05 PM
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Re: Old (1990s era) big screen TV problems

Hey I've got a 54 " Zenith I got for free, about a 1994 model, projection my folks bought it new.

It had your same issue, 3 times .

due to lightning , or underground power surge(from the underground house service )

Insurance covered some of the repairs.

There are 3 boards under the screen , one just needs repaired.

you got power, sound , no screen.

It cost me $285 at a local shop, it was well worth it.
they send the board out to a place out west and they do an exchange , and send you a rebuilt one.

Don't know how good your repair guys are out there, the guy I used is pretty cheap, but you drop it off at his business, to get it fixed at your house, you generally get hosed.

well good luck

you can do it yourself for half that. I didn't think I wanted to repair it myself, even if I knew which board was bad for sure, probably no return if you get it wrong.
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