Weird problem on my AKAI 54" projection TV - Videokarma.org TV - Video

Yamaha Nutz · #1 10-24-2007, 08:49 PM

Just the other day, my AKAI began to act up. Top and bottom are now convex/concave (bowed) and it isn't the convergence. I took the back panel off and cleaned everything, so the reflective surface is not the issue.

I am now thinking it may be in one of the (3) projective lenses. Perhaps something jarred itself loose????

HELP...and clues?

Thanks
Mark

***Eric H*** · #2 10-24-2007, 09:08 PM

Is this a CRT projection set?
Sounds possibly like a problem in the pincushion circuit.

Yamaha Nutz · #3 10-24-2007, 10:04 PM

I'll have to check the model number, but I purchased it in 2003???
1080 HDTV ready. Is it something I can perform myself, and thank you for responding

Mark

Here is a pic: (taken before the problem developed)

Geoff Bourquin · #4 10-25-2007, 11:52 PM

I've fixed a bunch of those sets with the convergence problem and usually the picture is bowed as well. Probably uses a pair of STK392-040. Some models have pico fuses near the ICs, and some just let the 1 or 2 ohm resistors go poof .
I called Akai a few months ago to order some parts for one of those and they told me they won't support it at all. Service manual, remote and a couple discrete parts were all they could provide. (and the service manual didn't tell me much). They told me that maybe Samsung could help me. (they make those for Akai). My customer and I were both so tired of the runaround we were getting that he decided to get a new set. To be fair, the runaround is not unique to Akai or Samsung. It seems to be standard procedure in the TV business these days.

But back to your problem...Is the convergence PERFECT? if it is, then those STKs might not be the trouble, but replacing those is always my first step with any geometry problem because they are so prone to failure. If you decided to change them, be sure to check the low-ohm resistors near the ICs after the old ICs are out, and be sure to unplug the convergence yokes when you do, or else you may just be reading the resistance of the yoke winding. Also, get the heat sinks squeeky-clean. If you leave old hard and crusty heat sink compound there, the new ICs won;'t make good contact and they'll fail real fast.

As long as I'm rambling on and on, Ill make a comment on the heat sinks. Some of them don't use the white grease, but use those rubbery "sil-pads". I always remove them, and use the white heat sink compound. Here's why: I studied how some of those are assembled, and found that often the sil-pad does not make good contact with the heat sink and/or the IC. It seems that when the screws are snugged down something warps a tiny bit, and the contact to the heat sink is poor. The grease will flow into the gaps and fill that space, giving better heat transfer.
Don't forget to check those little pico fuses if yours uses them.

A bunch of words: I hope some of them help

kx250rider · #5 10-26-2007, 11:31 AM

Geoff suggests the same as I would do.... The convergence board is the weak spot on most all projection sets. It also controls pincushion and other gemetry, and does weird things.

Just BTW: Shouldn't this be relocated to the Rectangular tube & Solid State thread?

Charles

***Eric H*** · #6 10-26-2007, 01:10 PM

Quote:

Originally Posted by kx250rider

Just BTW: Shouldn't this be relocated to the Rectangular tube & Solid State thread?

Charles

Done!

Yamaha Nutz · #7 10-26-2007, 01:39 PM

Thanks guys for the recommendations.

Findm-Keepm · #8 10-26-2007, 08:31 PM

Quote:

Originally Posted by Geoff Bourquin

As long as I'm rambling on and on, Ill make a comment on the heat sinks. Some of them don't use the white grease, but use those rubbery "sil-pads". I always remove them, and use the white heat sink compound. Here's why: I studied how some of those are assembled, and found that often the sil-pad does not make good contact with the heat sink and/or the IC. It seems that when the screws are snugged down something warps a tiny bit, and the contact to the heat sink is poor. The grease will flow into the gaps and fill that space, giving better heat transfer.

Amen! When I was in the Navy, we had an airborne IFF transmitter section that used Sil-Pads. We always had really low reliability on these, so a few of us tried using Heat Sink Compound on a couple of transmitters, and we tracked the serial numbers. Bingo! No more failures of the regulators. One did come back for repair, but only because of over-torquing/breaking of some captive bolts. Regulator(s) were fine!

Cheers,