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TOSHIBA 42AV500U Mysterious Problem    
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Joined: 21 Oct 2010
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PostPosted: Thu Oct 21, 2010 1:07 pm    Post subject: TOSHIBA 42AV500U Mysterious Problem Reply with quote

Hi, I have a mystery problem with my TV and have spent a ton of time researching it and over $200 trying to fix it. I am about to give up and Iím wondering if thereís any experts out there who may have any theories. I bought a 2008 TOSHIBA 42AV500U 42Ē LCD TV, after about 6 months of use we started to have trouble with the backlight firing up on the first try when the set was cold. I didnít think it was a big deal because it always came on after turning the set off and on again. Just after the warranty expired it developed a new problem, every once and a while the (screen would flash and the speakers would pop, and the sound would become garbled for 10 to 15 seconds). As time went on this problem began to happen more and more often. After a ton of hours on the internet Iíve found only one other person with this symptom, his set was under warranty and he said they fixed it by replacing the main board. I then found a place online and ordered a replacement main board, after replacing the board the problem continued. Next I figured I would just get all the parts I think might be the problem, so I ordered a replacement, (power board, power filter board, backlight inverter board). First I swapped the main board back to my old main board since that wasnít the problem, then I swapped my main power board and put in the replacement board, and still the problem continued. Okay I thought itís got to be the inverter board, so I swapped that for the replacement, this is the only thing that had any effect, the problem was still there, but seemed to be happening less often. After checking my original inverter board I noticed the 3 capacitors on the board were bad, (bulging tops), EUREKA I thought. My next assumption was that the caps were bad on both inverters so I ordered replacement caps, (Panasonic FMís), and replaced them on both inverters. The problem is still there, but the weird thing is it happens exactly every 12 minutes, (screen flash, pop from speakers, garbled sound for 10-15 seconds). I tested both inverter boards with the new caps for over 4 hours and both boards do it every 12 minutes exactly. Iím assuming that if it was a short or a bad solder point it would happen randomly, not every 12 minutes. Now Iím about to give up, the only board I havenít replaced is the LCD Controller and I donít think thatís the problem. Is it possible that the replacement parts could have the same defect my original parts have? Iím now thinking power supply again because itís the only board that would affect all the other boards, but I am not into electronics and have no idea what to check. I have checked all boards for bulging caps, residue on board, cracked resistors etc, and everything looks good. The TV picture looks great and the TV functions properly it just has some kind of short seizure every 12 minutes.
If any of you experts out there could offer some advice, I would be eternally grateful, I have been obsessing on this TV for the last month solid and have gotten nowhere.
Thank you for your time:

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