Question about Akai PT4298HD Rear Projection Television

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No sound or picture

I recently had a coolant leak onto my convergence board, because the coolant cover under the lens wasn't retightened enough. This caused a short (I assume) because when the set turns on all I get is a timer light on the front with no sound or picture.

I tightened the cover down, replaced the convergence board, cleaned up all of the coolant, and still nothing. I checked the fuse nearest to the power cord (FP801S) and it's fine. I'm thinking there is maybe another fuse that needs replacing but I can't see anymore.

Where else should I look? I have the service manual in PDF form but I'm not an electrician, so I'm having trouble following the schematic. I tried testing the voltage to the power supply with a multimeter but read nothing.

Please, please, please help me!!!!

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OK WHEN A BORD GETS SHORTED OUT LIKE THIS IT MOST LIKLY CAUSES PROBLEMS WITH OTHER BORD'S AND COMPONETS BECAUSE I WOULD GUESS THAT IT SENT A SERG THROUGH MOST OF THE SYSTEM I HATE TO SAY IT BUT I THINK ITS REDY FOR THE TRASH UNLESS YOU WANT TO SPEND THE $ ON THE PROS

Posted on Mar 24, 2008

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Clean lens on Mitsubishi VS 8087?


hello!really, you can't clean lens to improve the picture quality. it just won't make it worth. I've seen lenses and mirror covered with 1/16 inch layer of the dust, smoke, etc. Wiping them off didn't make much difference if your CRTs(picture tubes) are strong. If those are weak or coolant contaminated(cloudy), no cleaning will drastically improve the picture. Except for "basic" cleaning, which requires disassembling of the cabinet, detaching the mirror and spending couple hours to do so, there is not much you can do yourself. Replacing coolant requires 'top gun" skills, restoring CRTs emissions requires $1,000+ device and knowledge "how to" and 'how not to fry" tubes. If picture is not too bad, but out of convergence, there is nothing to do with any procedures, described above. Especially, if coolant leaked onto boards(very common problem). In any case, there is a MAJOR repair involved, possibly at the board replacement level. Not a D.I.Y. project.If nothing relates to your case, just poke set open from the back(carefully) on top of the "bulge". Clean it with "windex" or "invisible glass", using "bounty" paper towels and try to enjoy the show!good luck,Alex.

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If you have yellow coloring on everything, this is not a lens alignment problem. Either you have a color balance problem (weak blue) or the coolant fluid in one or more CRTs is going bad. The coolant liquid is supposed be clear, but with age it breaks down and turns yellow.

First, unplug the set and remove the back. Use a mirror if you have to, but look down at the top of each CRT using a bright light. They should be colored red, green or blue, with no yellow to muddy the color. That's a quick check on the coolant condition.

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I recommend getting the color right before attempting the focus. Bad coolant may scatter the light and fuzz up the picture, so check that out first and post back what you find.

If you have yellow fringes on otherwise normal colored objects, the blue convergence is off. This will also make lettering appear out of focus. Most RPTVs have a procedure for bringing up a convergence pattern (a grid of dots) using the remote control. The dots should all be white or have very little color fringing. Follow the directions, and make small adjustments, then check the effects all around the picture. Correcting one section may cause a change elsewhere. Use a ruler to make sure the dots stay in the right place; otherwise you may end up with a distorted picture.

Caution to other readers: do not try to adjust convergence if you have a "bow-tie" shaped picture in one or more colors. This indicates a convergence amplifier failure, which must be fixed first.

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1 Answer

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1 Answer

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