Samsung plasma PN50C550, fried Y-sus/buffer

[skeletonman]

Hi all,

I was experiencing a thin black line (horizontal, full width of the screen) and red sparkles on the screen (more noticeable on a white background or test pattern than normal tv).

I ordered a new Y-buffer figuring since it was just this minor issue, I wouldn't need to replace Y-sustain (or Y-Main as Samsung calls it).

I installed the new buffer board, the screen flickered red a few times, then "pop" and now both the y-buffer and y-sus have dead shorts to ground!

What could have caused this reaction ? I was very careful about part numbers, everything matched 100%!

I was trying to avoid replacing the Y-sus, since it cost me nearly $120 for the buffer alone - the Y-sustain would have doubled that cost!

How do I find what went wrong with the Y-sustain ? I can swap out transistors, regulators, etc if I know where to look.. I think the buffer is a lost cause.. there are 12 ICs and almost every one has multiple shorts to ground.. I don't have a hot air station to replace these anyway...

Thanks in advance..

[skeletonman]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

Update: I traced the y-sustain short to 2x 30F123 mosfets, under the heatsink near where the y-buffer connects.

I'm looking for replacements, but it appears china is the only source - I was hoping for a Canadian dealer so I could get the parts within days..

If I can get the y-sustain fixed, I have the old semi-working y-buffer to put back in (until I can afford to replace with new ones).

[tom66]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

This can happen with used parts - the buffers can be damaged by a cracked panel which can potentially damage the Y-main board.

[tw2005]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

This can happen with used parts - the buffers can be damaged by a cracked panel which can potentially damage the Y-main board.

Crikey. I hope it was not a used board @ $120. at SJ they're only $46

@ Skeletonman:

If you do browse through SJ for bits, be careful. I was looking at a listing for 42Cxxx model parts and they had them shown suitable for 50" models . Check the numbers just in case it's still an issue.

Also if you think just replacing the IGBTs is going to fix it you may be disappointed, there's a bunch of smd parts underneath that also might be dead.

pretty sure these also suffer xmain failures which can kill the y too so there may be more happening here than you realise.

prior to installing the Buffer, did you check it for shorts.

Y buffer LJ92-01680A, LJ92-01729A $46
Y-main LJ92-01683A $34
X-main LJ92-01682A $41

That's $121. maybe you could convince whoever sold you the buffer it was shorted, DOA and it just blew up your Ymain and would like a full refund? Unless it was a brand new board from Samsung?

[tw2005]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

can you list what part numbers your set and the PDP panel model too.

just found a better deal Payless Components. I've used him several times, really good, yet to let me down and sometimes he has stuff crazy cheap. also on Ebay.

http://www.paylesscomponents.com/cat...?q=LJ92-01729A
http://www.paylesscomponents.com/cat...?q=LJ41-06755A

$19 y-buffer LJ92-01729A (LJ41-06755A)

http://www.paylesscomponents.com/cat...?q=LJ41-08458A

4 Y-mains between $10-15, I think your repair option can be deleted now at this price.



http://www.paylesscomponents.com/cat...?q=LJ41-08457A
3 Xmains between $10-24 each

$40 for 3 boards!

I would strongly recommend gettingthe x and swapping all 3 at the same time to take your x completely out of the equation.

[skeletonman]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

Thanks guys.. the supposedly "new" y buffer was from http://www.electronicstvpartshop.com

$80 USD + $20 USD shipping + 13% tax = $113 USD, or $125 Canadian

Most parts range between $75 - $100 + shipping/taxes

Looking closely at the new buffer, it has a the same part and revisions, but it has the number "2" in a circle on the left, while the original has a number "1". Also the ICs are slightly different (the second set of numbers on the chips are different) and it looks like a refurb, because the chips are sealed with clear silicone, not that yellow glue.

Here's the part numbers:

Y-buffer
---------
Model No: 50UF2P YB CON
PCB No: LJ41-06755A
Rev No: R1.1 (09/11/06)
PBA No: LJ92-01680A
Buffer IC No: Panasonic AN16489A / 012P46B4

Y-main (sustain)
-------------------
Model No: 50U(F)2P Y-MAIN(1LAYER)
PCB No: LJ41-08458A
Rev No: R1.2 (09/11/20)
PBA No: LJ92-01728A HD / LJ92-01683A FHD
PBA Rev: AA3

X main:
---------
Model No: 50U(F)2P X-MAIN (1LAYER)
PCB No: LJ41-08457A
Rev No: R1.2 (09/11/18)

PDP:
--------
Model: S50SH-YB06


I never heard back from the seller after emailing them about the issue - hoping a paypal dispute will get the ball rolling.

I didn't realise there were smd parts that would blow on the Y-main also.. I didn't check the buffer for shorts before installing.. dumb move! I know it sure has a ton of shorts now!

[skeletonman]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

If I'm replacing Y main/buffer and X-main, should I replace the X buffer also ?

[tom66]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

The X-buffer is just an extension board, no need to replace it. (It's a plane of copper with a single poly cap on it...)

[skeletonman]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

Thanks, good to know

[skeletonman]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

tw2005 - where you from in Oz ? I just noticed you were an ozzie.. (like "Crikey" wasn't a giveaway lol)

I'm from Tassie originally, been in Canada almost a decade now..

[tw2005]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

tw2005 - where you from in Oz ? I just noticed you were an ozzie.. (like "Crikey" wasn't a giveaway lol)

I'm from Tassie originally, been in Canada almost a decade now..

From Brisbane, in Darwin.

Looks like yours has a different revision board but the ones I listed may still work.

[skeletonman]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

Got a response:
-------------------

All our TV parts are pulled from working units with crack screen in our TV
service shop. All parts are tested and guaranteed to be in 100% working
condition!
Sorry to hear about your TV problem:

I would like to ask you some question before I can issue RMA:

1- Do you read and accept our "Return& Warranty" before buy our items?

http://www.electronicstvpartshop.com...=72&Itemid=119

2- I have checked in our shop's record:
- First you ordered SAMSUNG PN50C550 LOGIC MAIN LJ41-C8382A LJ92-01701
LJ92-01702. (Mar 28)
- And then you order SAMSUNG PN50C550 Y BUFFER LJ41-06755A LJ92-01680A
(April 9)

As TV repair Technicians we never order these parts together to fix your
TV problem!( working tv with a thin black line)Can you send us a picture
of your TV problem? Why did you order them together to fix a problem not
related?

3- Are you trained TV repair Technician and doing repair TVs is your main
job?
4- Do you know the technic: how to test Plasma panel, Y buffer, and Y main
to make sure they are not short or not defective (not just by meter,
because multimeter itself is really limited to troubleshoot problem in
Plasma TV repair technic. These technics are shown in Samsung training
manual for Technicians)?

5- Do you know that before install a new buffer in, Technician must
perform some test and "hot measurement" to make sure Ysus board or Plasma
panel do not kill the new buffer?

If you can prove that you are TV repair shop or trained TV repair
Technician. We will happy to refund you this item (you have to ship back
our item first)

Thank you for your understanding

[tw2005]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

A note in their frequently asked questions section.

"The majority of our inventory is used TV replacement parts,"

[tom66]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

Sounds more like an accusation of "buyer has to prove it's wrong" rather than the other way around. If you paid by PayPal consider filing a dispute, if by CC then a chargeback.

[tw2005]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

Got a response:
-------------------

All our TV parts are pulled from working units with crack screen in our TV
service shop. All parts are tested and guaranteed to be in 100% working
condition!
Sorry to hear about your TV problem:

I would like to ask you some question before I can issue RMA:

1- Do you read and accept our "Return& Warranty" before buy our items?

http://www.electronicstvpartshop.com...=72&Itemid=119

2- I have checked in our shop's record:
- First you ordered SAMSUNG PN50C550 LOGIC MAIN LJ41-C8382A LJ92-01701
LJ92-01702. (Mar 28)
- And then you order SAMSUNG PN50C550 Y BUFFER LJ41-06755A LJ92-01680A
(April 9)

As TV repair Technicians we never order these parts together to fix your
TV problem!( working tv with a thin black line)Can you send us a picture
of your TV problem? Why did you order them together to fix a problem not
related?

3- Are you trained TV repair Technician and doing repair TVs is your main
job?
4- Do you know the technic: how to test Plasma panel, Y buffer, and Y main
to make sure they are not short or not defective (not just by meter,
because multimeter itself is really limited to troubleshoot problem in
Plasma TV repair technic. These technics are shown in Samsung training
manual for Technicians)?

5- Do you know that before install a new buffer in, Technician must
perform some test and "hot measurement" to make sure Ysus board or Plasma
panel do not kill the new buffer?

If you can prove that you are TV repair shop or trained TV repair
Technician. We will happy to refund you this item (you have to ship back
our item first)

Thank you for your understanding

Sounds very unfriendly.

It's a pity you found this forum after having problems. Not sure if it's worth corresponding further with them.

I always find it laughable the standard

"All our TV parts are pulled from working units with crack screen in our TV
service shop. All parts are tested and guaranteed to be in 100% working
condition!"

How can a TV be working if it's screen is cracked? Wonder if they consider the fact that since the parts are used, the TV was used and if it was on when the panel cracked , quite often it will short the panel and damage the buffer.

As for tested 100% working, that's generally

They claim it, very few do it.

I've even had a 30 year TV business claim it and before I made a purchase on a sustain / buffer set I asked them to check and confirm some key failure points for dead shorts.

I got the "we know TVs" bit, sure enough when it arrive the boards were DOA and dead shorted on the power input, takes like 2 secs to check + one buffer also shorted.

I lodged paypal disputes on the 2 suppliers got full refunds but I had documented evidence that I had asked them to check these and had not installed them, did not have to because I knew what to check.

Your situation could be tricky, they're already gathering evidence and they're wty is not worth a cracker unless qualified .

They'd know majority of people buying these parts would be DIY, not professional repairers who'd use new from samsung especially at the prices they are charging for used.

I would esculate to a claim and not get in a technical conversation.

I trust you're competent enough to fit the ribbons correctly seated, it'd take a bit of effort to misalign them to blow the board up.

You never tried realigning these whilst the TV was running by any chance? that 's a no no.

[tom66]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

One other thing a lot of these suppliers rarely consider is that people can get quite pissed off when their 1-year and month old TV dies. They smash the screen in frustration, or perhaps in an attempt to use percussive maintenance to solve a problem. They then take it to the local dump or sell it cheaply for spare parts but who knows what is wrong? Only way to be certain is put them in a good TV.

I think there's only a few sellers that do this like shopjimmy who get enough boards to make it worth it.

[tw2005]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

There's a definite difference between the LJ92-01729A (2010 dated)& LJ92-01680A(yours 2009), connectors and number of buffer ICs.
The ribbon connectors on yours , is it still just a flat ribbon inserted and lever down action or plug type?

your panel model is listed for the other buffer, but I'm starting to think that is a plug in connector on yours.

Will have to be careful, looks like Samsung did a revision on these. I was going to use the panel model in SJ but unsure if their info is 100%


This buffer is the same as your image

http://www.paylesscomponents.com/sam...41-06755a.html

I'm thinking this for the X

http://www.paylesscomponents.com/sam...41-08457a.html

This is one of the hardest TVs I've seen for cross referencing parts.

On the X and Y boards, there's a green barcoded sticker, can we see that and some clear sharp shots of the x and Y boards.

I'm hoping this is your Y board

http://www.paylesscomponents.com/sam...41-08458a.html

[skeletonman]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

Thanks for all the feedback, I will not be dealing with that company further, I'll file a paypal dispute.

I did not try adjusting anything with the power on - the y-buffer connections are plugin not ribbon cables, so very hard to screw that up.

I am DIY and new to TV repair, but I have well over a decade of experience in PC repair (just not at the component level, it was never cost efficient, cheaper just to replace a board). I studied general electronics repair for a semester, but never completed the course (got full time work and quit).

I found a Samsung training manual with waveforms, etc.. it's for a 42" model, but I assume there's little difference for a 50" model.. the only problem is, I don't own a scope.. is there a cheap model you guys would recommend ?

[tom66]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

What's your budget for "cheap"?

You can get a decent analog scope for about $50, which will do most of the stuff you need.

I used to use a Rigol DS1102E scope, the sister variant 1052E is about $350, it's a very powerful digital scope.

Now I've upgraded to a Rigol DS1074Z which is about $500 but has 24x the memory, a bigger high-pixel density screen, and intensity grading, among other features...

[tw2005]

Re: Samsung plasma PN50C550, fried Y-sus/buffer

post 17 edited, please re-check content.