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informative thread!
Steve's AV56WP74 Convergence Repair - with Pics
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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.
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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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.
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.
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.
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. :dontknow:
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
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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Have you tried http://elektrotanya.com/
ok i was able to replace the chips and all the 2w resisters but after putting it in a booting it up only the green and red auto converged and the chip in the middle of the bored as hot but the one on the outer was not so i turned it off and looked to that r854 had blown does that mean that that that chip on that side is bad?? can i just replace the bad resister ?? is it bad news when that happpens?? the one that seams like its working gets the heat sink to hot even touch is that normal?
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I have no experience with them. Buying semiconductors these days, particularly STKs, runs a very high probablility of getting bad parts. The problem is that even very good suppliers get bad parts every now and then because the brokering network is rather obtuse in asia. Sticking to the handful of reliable suppliers that we work with all the time has proven to be the only way to improve the situation. ACME, Electonica in Denver (NOT Electronix) and B&D are my go-to suppliers for these semiconductors.
The other problem with knowing if you have bad parts or counterfeits is that many failures are due to installation problems or failure to do adequate testing and alignment. Connecting chips with an open resistor or open supply line can destroy them, or running them without the yokes connected for very long can damage them. If there was some extreme alignment problem or excessive d.c. offset, this can cause them to overheat quickly and fail as well.
The other problem with knowing if you have bad parts or counterfeits is that many failures are due to installation problems or failure to do adequate testing and alignment. Connecting chips with an open resistor or open supply line can destroy them, or running them without the yokes connected for very long can damage them. If there was some extreme alignment problem or excessive d.c. offset, this can cause them to overheat quickly and fail as well.
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Hello,,,,I just found and joined this site today, Its one of the best I have found on the Internet including its policies.
I was looking for ideas to a problem I have had or created with my JVC rear projection tv. Its a AV56wp74 as described in this link. It had the same wavy lines and I ordered a "kit" from "tvrepairkits" and have installed the two chips, the resistors appeared good and none changed nor tested by removing one leg.
I reinstalled the board and NO picture, but have sound.
After many suggestions and rechecking all connections and soldering, same problem. I was told to check for tempature of chips, they are both cold,,,,,
I have read every post here, including examing the photos (great help), but i am still stumped.
I am not a tech,,,just a DIY that will try anything,,,,,,
Any help will be appreciated.
I was looking for ideas to a problem I have had or created with my JVC rear projection tv. Its a AV56wp74 as described in this link. It had the same wavy lines and I ordered a "kit" from "tvrepairkits" and have installed the two chips, the resistors appeared good and none changed nor tested by removing one leg.
I reinstalled the board and NO picture, but have sound.
After many suggestions and rechecking all connections and soldering, same problem. I was told to check for tempature of chips, they are both cold,,,,,
I have read every post here, including examing the photos (great help), but i am still stumped.
I am not a tech,,,just a DIY that will try anything,,,,,,
Any help will be appreciated.
I have a JVC AV-56WP30 that has a bluish green bow on both the top and bottom of the screen. Going into the convergence setup reveals that the blue shows through due to a lack of red in this area. The red convergence pinches in close to the center on both the top and bottom.
After some reading, I found this thread and many others discussing convergence issues dealing with the IC's. I figured that mine being 11 years old now and never having to change them, it was likely to be the culprit. I tested all the resistors, pulling one leg from each to test them individually, and found one resistor bad. R846 was burnt and when tested also showed no continuity. I went ahead and ordered two new IC's and a package of four 1.5ohm 1w resistors.
After receiving my new Sanyo IC's, I installed them both and replaced the resistor. Upon putting the convergence board back into the TV, it blew the same resistor again immediately. I found this to be strange, pulled the board and replaced the resistor again. Putting it back in the TV replicated the same effect again, blowing the resistor. I got out the multi meter and tested for continuity everywhere, found the service manual listed in this thread and tested nearly every SMD resistor and diode that I could find. I found no problems and am fairly certain that there are no broken traces or bad solder joints. I don't know how I could have tested more thoroughly.
I finally began to look into the trace where R846 is placed inline. That trace goes to the RV- (red vertical negative). I rechecked every single piece in that trace, replaced the resistor again and checked for continuity from the 28v input from the convergence power pwb to the output for the red convergence. Again, everything tested perfect.
I put the board back in and it blew the resistor again. I'm officially stumped. I take things breaking as an opportunity to learn something new and this has been a great experience, but my lack of prior knowledge in this field is leaving me stuck at this point. I'm hoping someone here might be able to give me an idea of where to look next. Maybe something from the convergence power pwb supplying too much power to the convergence board?
After some reading, I found this thread and many others discussing convergence issues dealing with the IC's. I figured that mine being 11 years old now and never having to change them, it was likely to be the culprit. I tested all the resistors, pulling one leg from each to test them individually, and found one resistor bad. R846 was burnt and when tested also showed no continuity. I went ahead and ordered two new IC's and a package of four 1.5ohm 1w resistors.
After receiving my new Sanyo IC's, I installed them both and replaced the resistor. Upon putting the convergence board back into the TV, it blew the same resistor again immediately. I found this to be strange, pulled the board and replaced the resistor again. Putting it back in the TV replicated the same effect again, blowing the resistor. I got out the multi meter and tested for continuity everywhere, found the service manual listed in this thread and tested nearly every SMD resistor and diode that I could find. I found no problems and am fairly certain that there are no broken traces or bad solder joints. I don't know how I could have tested more thoroughly.
I finally began to look into the trace where R846 is placed inline. That trace goes to the RV- (red vertical negative). I rechecked every single piece in that trace, replaced the resistor again and checked for continuity from the 28v input from the convergence power pwb to the output for the red convergence. Again, everything tested perfect.
I put the board back in and it blew the resistor again. I'm officially stumped. I take things breaking as an opportunity to learn something new and this has been a great experience, but my lack of prior knowledge in this field is leaving me stuck at this point. I'm hoping someone here might be able to give me an idea of where to look next. Maybe something from the convergence power pwb supplying too much power to the convergence board?
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Please read the first ten posts of the convergence repair sticky in the DIY Repair forum VERY carefully.
http://www.hometheatershack.com/for.../5600-crt-based-rptv-convergence-repairs.html
Do you have both positive and negative supplies at the ICs? If not, there is a good chance you blew a chip and it would explain why you are burning up resistors. It is also unlikely that you got original Sanyo chips, considering all of the copies out there and they have been out of production for several years.
http://www.hometheatershack.com/for.../5600-crt-based-rptv-convergence-repairs.html
Do you have both positive and negative supplies at the ICs? If not, there is a good chance you blew a chip and it would explain why you are burning up resistors. It is also unlikely that you got original Sanyo chips, considering all of the copies out there and they have been out of production for several years.
Thanks again for your help and reading about my problem. After testing all power supplies again, I decided to go ahead and call up a local electronics store to see if he might have any original Sanyo IC's. What he did happen to have were known good STK392-150's that were originals pulled from a known working convergence board. I installed them, changed the resistor again, and bingo! My guess is that the original "Sanyo" replacements that I purchased were cheap garbage from China. Oh well... It cost me a few extra hours and a lot more confusion, but it's all working now. Thanks again!
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