Samsung PS50A2476, No Picture

[flexy123]

I have a old Samsung PS50A2476 which (of course) crapped out on me last month (didn't turn on), the usual bad caps problem which I replaced and the TV worked brilliantly again for some weeks.

(Noteworthy to mention that we don't use this TV at all, but I wanted it functional)

Today I am trying to turn it on, it seems to get power, this all looks alright BUT NO PICTURE. By turning it off/on a few times I managed it to display picture for a very short time, but now it's gone again. (Usually when I turn it on you see some information on the screen about signal sources etc. there is nothing).

When I turn it on, the red LED goes off (as it should) and then blinks (I assume this is where it looks for a valid signal, nothing on screen etc, and after 20 mins or so the TV shuts off again).

We are in Spain and we always have power fluctuations and outages, today it seemed we had another one since all PCs were down, so I suspect this one reason....this already cost me several PC main boards etc...

I opened the Plasma again today and checked for bad caps (which is idiocy since as said I replaced them all just a few weeks ago) but I can't see any bulging or leaking caps. Just from guessing I'd say the power supply and caps are alright.

Any idea what it COULD be? And how I could trouble-shoot this without super-extensive knowledge although I have a DMM, replacing caps etc. no problem.

Thanks!!

[ReeceyBurger123]

Re: Samsung PS50A2476, No Picture

Images of the boards in the set please ?

[flexy123]

Re: Samsung PS50A2476, No Picture

I am a dummy, closed it again without taking pics or writing the types of boards down. Will have to do this anyway, tomorrow and then also upload some pics.
(From my entirely preliminary understanding, seems the set is stuck in power saving mode, which according to some might be the Y-board.)

Set is sort-of obscure, so will check the boards tomorrow.

[ReeceyBurger123]

Re: Samsung PS50A2476, No Picture

I ask I think you got the model wrong cant find a thing on the set. Let us know bud

[Alastair E]

Re: Samsung PS50A2476, No Picture

It'll be an A450/6 I guess--With buggered Cont-Board F/W caused by cruddy psu caps....

[flexy123]

Re: Samsung PS50A2476, No Picture

I ask I think you got the model wrong cant find a thing on the set. Let us know bud

Nope, model is right. It's the European version I assume of the A450, it was one of the first available 3D Plasmas. There was some info on the web years ago but it's now indeed all gone, I cant find anything either.

>>
With buggered Cont-Board F/W
>>
Could you elaborate on that?

[flexy123]

Re: Samsung PS50A2476, No Picture

PS50A476 <----- I DID make a typo ;/

[flexy123]

Re: Samsung PS50A2476, No Picture

I had it open today and wrote down PCA numbers, so the
Logic (?) LVDS board is LJ92-01517A, Rev.2.0
There is a big ink stamp on it too that says BA3

I found on ebay the same board surprisingly cheap, it says Rev2.1 on the PCB but there is an ink stamp on it which says AA3, otherwise it looks identical.

I assume this would work (ASSUMING there is something with this board)????

I found the thread here about self-testing the logic board. Unfortunately this thread doesn't help me in the slightest. The thread said unplug everything including the LVDS cable (which I assumed was the biggest ribbon cable, it had even sort-of handles on it), and to jump pins 3/4 on the JMP connector, and then turn on the TV.

This is exactly what I did, but the article did not mention what is supposed to happen when I do this. Nothing happened, still no picture.

[Alastair E]

Re: Samsung PS50A2476, No Picture

With the links jumpered and only LVDS disconnected, If all is well with SUS boards, buffers, PSU and Cont board--It'll show test-patterns...

A fault on any of the panel boards above will make for no image at all....

Test the panel voltages, Vs, Va, VSC, VSCAN and VE, report back...

[flexy123]

Re: Samsung PS50A2476, No Picture

Update:

I got me a logic board from ebay and replaced the logic board.

With the replaced logic board, the green led blinks every second indicating that the logic board is ok. (With the old logic board, the green diagnostic LED was extremely erratic, like flashing a code, or it was always lit, or entirely off)

So...with the replaced board I also have THIS (before I had no picture at all)



Left half of the screen is some greenish crazy pattern and right part reddish.
But OSD, Menus etc. don't work, but otherwise remote etc. seems to work.

BEFORE I replaced the board, when I still didn't have any picture at all I tried to measure VS and VA. I did not get any reading (I had set the DMM to 600V, if anything there were a few V on there (it showed 3 or 4 or the display), but not even remotely to the 207 which should be on VS or 56 which should be on VA. On the other hand, since I didn have any picture there, maybe it was normal there was no voltage?

So what can I do next? I do of course not 100% know whether the logic board I replaced works, but I ASSUME it does. (When I jumpered the board and disconnected from the main board, I got the same stuff on the screen like above)

Edit: I also disconnected and re-seated the ribbon connectors multiple times, even cleaned them with alcohol, I don't think it's a faulty connection with a ribbon.

Edit2: The logic board is Rev2.1 vs Rev2.0 of the old board, stamp says AA3 vs. BA3 before, otherwise it looks 100% identical. Does this matter?

[flexy123]

Re: Samsung PS50A2476, No Picture

(domain expired so the pic was not showing, bummer. Should show now)

[flexy123]

Re: Samsung PS50A2476, No Picture

When I check those training manuals, and from my rather limited knowledge, it always points to Logic Board Failure.



This right image looks VERY CLOSE to what I see.

I also did the Logic Board test and could not get any proper image, the training manual for the 2009 PDPs (earlier I cannot find) says if the Logic Board cannot display its internal test patterns it's the logic board.

Now I am trying to get the very exact, identical Rev somewhere from China