Need some help with sammy plasma

[Mtek325is]

Hi im new to the forum im from the uk and this is my first post.
Im in need of some help with a samsung ps50q96hd which im "trying" to fix
The tv would only click on and off and i narrowed it down to a faulty buffer and ysus board.
I replaced both upper and lower buffers and the ysus board with items purchased from an auction site. All the voltages were correct from the psu so ive plugged it all in and turned it on, the standby light would stay on and not click on and off but the panel wouldn't light up so I'm messing around with the remote when the top ic starts smoking so i pull the plug immediately.
I give it another go and what i think was a couple of fets popped and a capacitor got bulged.
One of the fets on the new board looked a bit dodgy underneath like the same one on the original board so do you think the ysus i purchased was already knackered and blew the new buffers as well or am i looking at a dodgy panel?
Just thinking it all came from the same tv so wouldn't it of blown in that first..any help much appreciated rik

[tom66]

Re: Need some help with sammy plasma

You are probably looking at a bad buffer board (from eBay) which has damaged your Y-main. This is one of the reasons I don't trust used buffers on eBay. They're mostly pulls from cracked screen TVs, but the act of cracking the screen can damage the buffer.

That FET looks fine to me.

Would be very strange if a bad buffer bloated a cap on the Y-main. Perhaps the Y-main you received was defective as well.

[Mtek325is]

Re: Need some help with sammy plasma

Thanks for the reply so you wouldnt think its a bad panel then, is it possible the power supply is bad and caused the buffer to burn out then the ymain on both the new and original boards? The voltages were ok to all boards though. If i turn it on without the ymain attached it stays on standby. This is the cap that bloated.

[tom66]

Re: Need some help with sammy plasma

Wow yeah, if that cap's popped you've probably got a WAY too high Vs. More than 250V. Rating is around 200V for these panels. Your X-main may also be bad due to excessive Vs.

I'd say a bad panel is unlikely, it's very uncommon on these older panels.

[tw2005]

Re: Need some help with sammy plasma

Yep, looks like you're another victim. Not quite sure what you're trying show in the photo but the soldering looks factory orignal.

I always check for shorts now on any secondhand buffer or ysus board I get regardless of where it comes from including the major sellers.

They all claim the gear is tested, ok! If you got the boards from one seller notify immediately and get your money back.Assuming you used Paypal I usually lodge a Paypal dispute which I find pushes it along as i believe they reverse the transaction, suspend the money until it's resolved which sellers find annoying.

There's 2 stages, dispute and then claim.time limits apply.

The ysus is usually a fairly easy fix and generally cheaper than getting a board.

I found getting upper buffers virtually impossible and are quite expensive as a rule.

I have used successfully buffer boards from the previous 50Q7 models which use a different ymain but the buffers are virtually identical and direct fit.

Edit: have not seen those larger caps bulge like that before. I don't think they're cheap either, I had a SJ supplied board which had one damaged with the pin pulled out of it.

[tom66]

Re: Need some help with sammy plasma

Will 50Q7 fit 42Q96?

[Mtek325is]

Re: Need some help with sammy plasma

The voltage from vs was 207v, exactly what it says on the sticker.

[tom66]

Re: Need some help with sammy plasma

Were other voltages like Vset, Vsc OK?

[tw2005]

Re: Need some help with sammy plasma

Will 50Q7 fit 42Q96?

No, but he quotes 50Q96HD?

[Mtek325is]

Re: Need some help with sammy plasma

Thanks for the reply im on a real learning curve here with alot of reading up about these problems and the diagnosing. You learn from your mistakes and i will get it going eventually just try not to spend too much on it now......and get my money back

[tom66]

Re: Need some help with sammy plasma

No, but he quotes 50Q96HD?

My error. Could've sworn I read 42Q96.

[tw2005]

Re: Need some help with sammy plasma

Pretty sure the Q96 is equivalent to Q91 here, ymain is the same from what i can make out. Cricket time, gotta go but I'll scratch around and see if I can find something in my older posts for part numbers and clarification.

[tw2005]

Re: Need some help with sammy plasma

My error. Could've sworn I read 42Q96.

LOL, I just checked myself just in case I was about to put my foot in my mouth before I posted as it crossed my mind too.

[tom66]

Re: Need some help with sammy plasma

Very few people test parts once pulled.

Here must be a damning piece of evidence:
https://www.google.co.uk/search?q=KA...%3B1728%3B1152

Crappy PSU with bulging caps on it For sale, only $$$! Seriously, how could no one who was "testing" the power supply not spot that?

[tw2005]

Re: Need some help with sammy plasma

Part numbers of the alternate buffers i used.

https://www.badcaps.net/forum/showthread.php?t=21637

[Mtek325is]

Re: Need some help with sammy plasma ps50q96

Little update to the thread, had another muck around with the tv today and decided to swop a few boards as the lot i bought had every board for the tv,
So i swopped the power supply and xsus just to see if any voltages changed anywhere but it was the same as the stock boards.
So i thought i might aswell change the av board and in doing so fired it up whacked the hdmi in and i got sound out of it, so im thinking the av board may of shorted the y-main or buffers previously is that possible? Also the av boards look different and have different numbers can anyone shed any light on why changing it gave me the sound back.

[Mtek325is]

Re: Need some help with sammy plasma

How do you attach more than one pic only uploads one

[tom66]

Re: Need some help with sammy plasma

Manage Attachments below the reply window. Add all your attachments using the "Browse" button, one file for each field, then select "Upload".

[Mtek325is]

Re: Need some help with sammy plasma

Heres the other board

[Mtek325is]

Re: Need some help with sammy plasma

Yeah did that but only uploaded one im on an ipad if that helps