No image only audio works on Samsung plasma PN64E550D1XZA

[jaburns89]

Hello,

Samsung plasma PN64E550 made some popping noises when turning on, the audio still works but there is no image on the TV. I have checked the screen for cracks with a flashlight and did not notice any (are cracked panels fairly noticeable?) There is no light at all on the screen, even in a dark room and visually I didn't see any burnt/bulging caps or chips.

I've tested for voltage here and there based on other threads i found and couldn't really pinpoint the problem. Also tried the fast track manual on toms service guides with no luck. And after reading through what seems to be like 100 pages of troubleshooting on forums and what not i'm pretty confused on the correct way to trace out and identify the failed board. I ended up buying and replacing the x and y main boards but still no image on the TV. What else can i check or test at this point? I have an electrical background so testing for correct voltage here and there would be no problem if i had some guidance on what to test. Any advice would be greatly appreciated!!

X board: LJ92-01788B
Y board: LJ92-01789B
Both these parts matched my originals as well as the rev number. Bought off ebay from a tv repair company, who says they were tested in a working tv set.
Pics of the tv boards: https://photos.app.goo.gl/zObWTL8gxrhRdls93


Thanks,
James

[Danstona]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

Im going to say its an issue with the power board. the X and Y boards on a set like that should give you some visual picture issues, but not popping sounds and no picture. Look closer at the power board.

Hard to see from photo, but take a closer look at the white rectangular capacitor between the two aluminum heatsinks. See if its buldged.

[freakaftr8]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

Popping sounds are almost indicative of shorted out buffer boards. I would disconnect both buffer boards out of the equation in and repower up and see if you have proper voltages from the power supply

[jaburns89]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

Ok appreciate the replys, will try that and report back. Can i remove just the ribbon cables from the buffer boards that go to the screen and test or do i need to remove the buffer board at those white connections from the x/y main boards as seen at the left in this pic: https://photos.google.com/share/AF1Q...h0eUNieHlIVnZ3

I checked out the white square cap and it is not bulged.

Thanks

[jaburns89]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

I ended up testing for Vs with just ribbon cables removed from the buffer boards, and once after removing the whole buffer boards from the x and y main boards, with the same results for both tests.

- Vs at 0 while the tv is plugged in to receptacle and red led indicator light on front of the tv is on

- Pressed the remote power-on button and Vs slowly rises over a couple minutes to about 6 volts.

When pressing power-on I hear what sounds like a relay kicking in maybe coming from the logic board and I've heard this same noise during power up while the tv was working normally before.

Does this mean a bad power supply?

Thanks

[jaburns89]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

Any ideas or where to go from here? I think at this point it is narrowed down to a bad power supply, main, logic, or buffer board.

[freakaftr8]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

Ok check fuses on power supply. Especially the one in the middle. Also check mosfets on the left for shorts. Common problem with this power supply.

[jaburns89]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

Fuses were good. Found a burnt up mosfet and possibly a few other damaged items surrounding it. Noticed it by removing the power supply board and looking at the bottom side. When checking the mosfets for continuity on the power supply board it seems they are all a little different.. Am I checking the outer legs to the inside leg and if it has continuity is it shorted?

Here are the pics: https://photos.app.goo.gl/NllzESJBthirbSZo2

Its the top most mosfet on the center heat sink.

I can solder but i feel like there is probably more components fried than what looks burnt up. Is this something a repair service could fix easily or would I be better off buying a refurbished board off ebay, or even a new board from here: http://www.samsungparts.com/Products...44-00515A.aspx ?

Thanks

[freakaftr8]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

Holy sweet Jesus! Replace that power supply! That was a high voltage arc from bad soldering that went supernova!

Imho that's too badly damaged or same to warrant repairing. I've seen solder connections d on mosfets go bad bit this is by far the worse iv e Seen! Lucky that didn't start a fire!

[jaburns89]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

Well the new power supply fixed my issue and the tv works. It even works with all my original boards, so it seems it was only the power supply and it didn't take out anything else.

Bad news is I somehow ripped/broke the bottom ribbon cable for the Y buffer board. Noticed after i had installed the power supply, don't know how i did it. So now there is an inch wide black bar at the bottom of the tv.
Pics: https://photos.app.goo.gl/hlsfmG8EYr8Sr9U52

Is this something I can fix? To me it doesn't look like a quick and easy fix, looks like I would have to remove quite a bit just to get to it. I can live with it i guess, its not too noticeable.

To everyone who commented, thanks for the help and advice! Greatly appreciated.

[freakaftr8]

Re: No image only audio works on Samsung plasma PN64E550D1XZA

That's unfortunately unrepairable. Just leave it like it is. It could get worse if you move it around. At least it's on ythe bottom . Glad the tv works.