Steve's AV56WP74 Convergence Repair - with Pics - Page 9 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #81 of 103 Old 01-15-12, 07:18 PM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

informative thread!
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post #82 of 103 Old 01-22-12, 12:56 PM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

Thanks for all the info in this thread. As an electronics repair newbie, I successfully repaired my AV56WP74 using the X480301 kit recommended by gunsmoke. In case there are others like me who have little/no experience working on PCB's, I thought I'd share my experiences in that regard:

Tools used: 30W soldering iron, desoldering wick (Radio Shack), tube of thermal paste (cheapy stuff from Radio Shack), 0.062" 60/40 rosin-core solder (I bought a roll of 0.032", which might have worked even better, but the 0.062" stuff I already had on hand seemed to work fine).

First remove the old solder from all the solder joints (I only replaced the convergence IC's - my resistors appeared fine and ultimately were). This process is pretty straight-forward - just pierce the wick with the pin sticking up from the joint (takes a bit of wiggling) so the wick is on top of the solder. Place the soldering iron on top of the wick until the solder below melts and is absorbed by the wick. Lift the wick and iron simultaneously and you should see all the solder missing from the pin and PCB hole. I found I could do 3-4 pins before cutting the wick and starting over forcing a new hole in the wick. It was a little tedious given there are a lot of pins, but worked very well.

Once the solder is removed, remove the two screws mounting the convergence IC to the heat sink. Mine could then be wiggled loose from the heat sink and a little more wiggling freed the pins from the PCB holes. Clean away all the old thermal paste. I used automotive MAF cleaner since it was handy, but alcohol or similar should work fine. You should also clean the PCB holes, but I wasn't sure what was safe to use, so I didn't touch them. Apply thermal paste to the back of the IC and smooth/spread with something to leave a relatively thin and uniform coating (I used a 6" steel ruler). Getting all the pins into the PCB just takes a little wiggling and patience. My new IC's pins weren't perfectly aligned, but I found by tilting the IC a bit and starting at one end, I was able to wiggle it a bit and gradually tilt the IC until all pins went into their holes. Now position the IC against the clean heat sink, smear it around a bit (without pulling any of the pins out of the PCB), and reinstall the mounting screws. If you installed too much thermal paste, it will get pushed out at this point. Mine only pushed out enough to form a small ridge all the way around. Wipe off the excess if necessary.

Now flip your board over and get ready to solder. If you're buying solder, I'd buy smaller diameter stuff, but I used some 0.062" I had on hand. Once the iron is hot, place the tip of the iron so that it's touching both the pin and the "trace" - the trace is the metal part of the PCB surrounding the hole. Touch the solder to the pin above your iron, and solder will be drawn down the pin into place on the PCB trace. If your iron is clean and making good contact, it just takes a second or two for all this to happen. Once they're all done, it's time for a beverage and preparation to put the PCB back into the TV. Once it's in the TV and working, it's time to remind your wife what an awesome man she married!

Thanks again for everyone's help!

AM.
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post #83 of 103 Old 02-14-12, 01:57 AM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

i was wandering if amazon would be safe bet for STK394-160
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post #84 of 103 Old 02-14-12, 08:34 AM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

Amazon does not sell any ICs. The question is what vendor are your chips being supplied from when you buy through Amazon? I strongly suggest sticking with the vendors recommended in the convergence repair sticky and confirming with them that they are selling original Sanyo parts. If you want the 394-160, I would try to find them from hitachi in one of their kits. Many of the other supplies of these chips have proven to be problematic.

As I have said many times, experienced servicers learned long ago to not risk buying cheap substitutes and that even some of the major distributors sell bad parts occassionally. Stick with a trusted supplier like Acme, B&D, or Electronica (not Electronix). Even those sometimes cannot get the original ICs any more but they at least do their homework to find the best suppliers of aftermarket ICs.

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post #85 of 103 Old 03-07-12, 09:53 PM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

I am trying to repair an AV56WP74 TV with the convergence problem from this thread. Here is what happened I replaced the 2 ICs using the 394-160 ICs, and also replaced 2 burnt resistors, and checked the rest. using a fluke 12 meter, it has never lied to me. So I guess I have to trust it. I turned on the TV, and tried to auto adjust the convergence, and could not get it to converge, So I felt the heat sinks 1 was warm 1 was cold so I figured 1 was sent to me dead. Before I got the ICs delivered to me the children of the house decided to plug in the TV when no one was home, Question is could that have done any damage without the Convergence board in the TV? When I went back to the job the TV was still plugged in, but was not turned on. I have since received a new IC. but was looking for any other suggestions prior to me replacing the suspected IC, and trying to auto convergence again.
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post #86 of 103 Old 03-11-12, 08:19 PM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

Steve could you give me some Idea why 1 IC would work and 1 wouldn't. Background for my request. I followed your entire procedure. Even swapped ICs from 1 side to the other and for some reason the IC on the heatsink near the BLUE connector will not `come on, I metered all the major components, had to change all resistors only because 2 of them were discolored, and metered open. I have re read the data sheets. And I just can't figure out why 1 IC is not ON.
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post #87 of 103 Old 03-11-12, 08:47 PM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

Have you verified that you have power to that IC?

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post #88 of 103 Old 03-11-12, 09:26 PM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

I will double check everything in the mourning. input voltage is on pin 10 correct?
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post #89 of 103 Old 03-11-12, 09:34 PM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

Also Do you have a source for a Schematic for this TV I haven't found a good 1 on the net. only block diagram nothing showing connections to the main board.
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post #90 of 103 Old 03-23-12, 10:45 PM
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Re: Steve's AV56WP74 Convergence Repair - with Pics

I have tried all my sources to get a schematic for this TV. They have sent me all they have, and there is nothing really usable, a lot of block diagram stuff. I am going to the Philippines in a few weeks for a visit, and will try some sources there. I have some Chinese friends who have gotten me schematics in the past.
I have yet to repair this TV. The main power to pins 5 and 10 of the ICs is about 28.5 VDC, The Negative voltage is 29 VDC. but the negative side of the Amps on the 1 that is working, is different than on the that's not. I haven't figured out why. I haven't worked on projection TV's since the late 2002, I even sent my findings to an old TV guy I know, and he is scratching his head. Should I send you the measurements I have for the Ics, maybe you can see something we are not seeing?

John Thompson
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