Samsung PN 58B550T2F/T5F

[robgsamsung]

Hello... thanks to tomcat for getting me here... Hope I am not as lost on the repair side... Have a Samsung plasma PN58B550T2F/PN58B560T5F. My brother asked me to look at it, as I have had success repairing other sets... and luck... it is a wonderful grace when it is on your side... any way. The screen comes on very faint with colors and fluorescence, some of screen blotched out. The PCB (small board under the control board)(I know you know... that was so I communicated it clear) is blinking one green led. The VS voltage is low at 188/187 should be 201, VA is low at 51 should be 55. Both show consistent 3 to 4 volt low. I am not sure where to put the probes, or ground probe, for the smaller voltages... 5v etc. I know... it sounds foolish, that is what they are there for ... right, but i did not want to make a mess of it. so i have gone no further. If I knew exactly how and where to measure for further info... i would do so. The set worked fine and then just poof? So i am inclined to think that the lower voltage is not something that I should try to trim out on VS?VA POT adjustments, but more a failed part on the power board. The caps look great, model is DEC 2009. If I disconnect the Y board cable, I have no picture, I do have picture if i disconnect the X board, but no change, faint, pixelated, florescent and blotchy and not really total screen(but that might be useless info). I tried resetting the ribbons, but no change and that does not explain the voltage diff on VS, VA. My brother said it was repaired by Samsung once for loud buzzing, and that he has always had 2 very very faint lines visible on the TV, but they were so faint, and only recognizable during certain screens etc, they did not really bother him. So he just let them be. Well that is the Any ideas, please let me know?

Thanks,

Rob

[tom66]

Re: Samsung PN 58B550T2F/T5F

The X-main has most likely failed.
Depending on how good you are at testing semiconductors and tracking down faults I'd suggest you just swap the whole board.

[robgsamsung]

Re: Samsung PN 58B550T2F/T5F

Thanks Tom,

Can you tell me if there is any way to confirm X Board failure? Voltage on VS and VA is the same with X Board disconnected. I would hate to overuse your valuable expertise, by asking for help on component level diagnostics...it is fun and a journey to uncover a problem... but that journey does not need to be to hell and back ... with my level of experience ... that might be only the half of it .. ha . Thank you for your direction and an X board replacement is a can do... for sure. Thanks again.

[tom66]

Re: Samsung PN 58B550T2F/T5F

With a low Vs you'd get a picture with partial pixel discharge (i.e. lots of dead pixels.) But it'd still be sort of visible.

However when you see a purple image that's because the panel isn't emitting the right light (it's emitting far ultraviolet and only a little violet, visible light.) This is because the sustain waveform isn't being properly generated. Also, the erase voltage (Ve, I think) goes AWOL, so the panel isn't erased on each cycle properly, leading to after images.

To test the X-main you need an oscilloscope and a 10X probe. If you can acquire one of those, testing then is possible.

[robgsamsung]

Re: Samsung PN 58B550T2F/T5F

Thank you... Here are a few pictures to confirm i have not misrepresented the picture.

Thanks again

[tom66]

Re: Samsung PN 58B550T2F/T5F

That looks vaguely similar to my problem with this Samsung:

Now mine had a bit of picture corruption too but I later found out the X-main had some other signals routed through it, and these were getting lost.

So the symptoms look similar (Zsus = X-main):
https://www.youtube.com/watch?v=Bmu12mCOKcU

I really wish I took a picture of the Samsung PS-42Q96HD I repaired, because that is more similar to this set, and it had a very similar dim image, also the X-main at fault.

[robgsamsung]

Re: Samsung PN 58B550T2F/T5F

What can I say... you are a Technology God. I will send my brother a copy of the messages... so he can see the progress. Thanks for making me look like a hero. I will order the board. If you have any suggestions on reliable order points let me know. Thank you again for the lift.

Sincerely,

Rob

[robgsamsung]

Re: Samsung PN 58B550T2F/T5F

OK.... Here is another probably ignorant question... the black pin connectors on the X board that go to X Buffers ( there are 4 of them) are very hard to pull apart. Am I missing some release. I do not want to force apart? and break something. Is there a trick to releasing or disconnecting the big black block pin connecters - attaching one board to another?

Thank you

[tom66]

Re: Samsung PN 58B550T2F/T5F

Can you post a picture of these "X Buffers", I have not heard of such a thing on a plasma display before.

[robgsamsung]

Re: Samsung PN 58B550T2F/T5F

Hey Tom,

Here are the tough guys. I know .... you are going to tell me ... Just Pull... bu they are really tight. i do not want to damage anything. I thought they might have a neat little release on them somewhere, but I think I just need to wiggle them. What do you think. As far as your question on the x buffers... I thought that was what the boards to the right of the x main were.

[tom66]

Re: Samsung PN 58B550T2F/T5F

Yeah, buffers is a generous term They are just a convenient and lower cost way of connecting lots of lines together. I think Samsung calls them X-extenders.

Anyway, there is a little plastic extent on each side. You pull the extent out, the cable will them come out.

If you damage the cable too much on the X-main side, the plasma panel will not work properly (it will not be possible to reconnect), so be careful. On the Y-main side any damage causes lines on picture, also unrepairable.

You could also unscrew X-main and disconnect it from the extender board.

[robgsamsung]

Re: Samsung PN 58B550T2F/T5F

Thanks Tom... DRJP responded as well. I did mean the 4 connectors that connect the boards ... and DRJP confirmed they just need to be eased out. Thank you again for being so kind to respond. I will sloooooooowwwwly work the board to board connectors apart.

On ward and upward... Thank you as always!