Samsung PN50C550G1FXZA

[smpstech]

Guys, I have a question about the Y Sustain Board. On this TV that I am working on, I found a short across 2 X 30F123 transistors and also SMK1360 on the same heat sink. I am suspecting the Y Buffer board is what caused it but I hate to change things just because. Failures upstream usually cause failures down stream but before I change the Y buffer Board, has anyone a better way of determining the Buffer board is bad. The DMA on the Buffer board has Part#an16489A and I can't find a Diagram for it. Samsung Semiconductor web site doesn't have anything and there are no test points on the Buffer board.

This would have been so much easier if I had a schematic to go by.

[rccrasher65]

Re: Samsung PN50C550G1FXZA

I do believe Tom has a link to the test you can do for the buffer board. I'm pretty sure he will respond. He helped me fix all my plasma's, along with all the other guy's on here. I had this same set, mine had a bad panel. I do have most of the boards for this set, if you happen to need them. I'm also located in Pittsburgh, Pa. very close to you.

[smpstech]

Re: Samsung PN50C550G1FXZA

When you say Panel, Are you talking about the main Plasma display? How much are we talking about for the Y Buffer Board or Y Sustain? I understand getting the exact board is tricky since the revisions can make a difference.

[smpstech]

Re: Samsung PN50C550G1FXZA

I found the following components shorted on the Y Main Board. Q5408 On one heatsink (today I found)and Q5401, Q5402 & AUK SMK1360 on the other heatsink and this is from yesterday's finding.. I don't like the fact I found Q5408 Shorted Drain to Source too today. I don't have a schematic but this is pointing to the X-Sustain also. Now I am beginning to wonder if the main Plasma Panel is bad.

[rccrasher65]

Re: Samsung PN50C550G1FXZA

When you say Panel, Are you talking about the main Plasma display? How much are we talking about for the Y Buffer Board or Y Sustain? I understand getting the exact board is tricky since the revisions can make a difference.

yes, I had horizontal lines on the display. I have the all the boards, except y-main. PM me for details.

[smpstech]

Re: Samsung PN50C550G1FXZA

yes, I had horizontal lines on the display. I have the all the boards, except y-main. PM me for details.

Thank you for your reply. I still have some troubleshooting to do. If the Main Panel is what caused the Y-Main to fail, then the TV is junk.

[smpstech]

Re: Samsung PN50C550G1FXZA

Does anyone know how to check the Y-Buffer Board on PN50C550G1FXZA with an Ohm Meter. I was able to find the VSS and VCC pin on one of the 20 pin Octal Buffers and I didn't see any shorts but I might be missing something on the main IC's. So Far, I found a couple shorted Transistors on Y Main Board. X-Sustain Transistor appear to be OK.

A Schematic would be helpful.

[rccrasher65]

Re: Samsung PN50C550G1FXZA

Here is a link to the video, shows you how to properly check buffer board for shorts https://www.youtube.com/watch?v=51SZ...y&noredirect=1

[smpstech]

Re: Samsung PN50C550G1FXZA

Here is a link to the video, shows you how to properly check buffer board for shorts https://www.youtube.com/watch?v=51SZ...y&noredirect=1

At work I can not see the tube. But the only good one I found on you tube was for a board that wasn't exactly the one I have. The Pins and test point he was referring too was slightly different than the one I have. The Y Buffer Board that I have, the 2 middle Connectors seem to have all the pins Common to each other but the outside 2 Connectors are different. I will still go home and see if this is the same video I saw. Thanks anyway.

[rccrasher65]

Re: Samsung PN50C550G1FXZA

Your probably not going to find the same board as you have to show how to test y buffer. I could not PM you back will try again.

[tom66]

Re: Samsung PN50C550G1FXZA

Post a picture of your Y-buffer board.

[smpstech]

Re: Samsung PN50C550G1FXZA

Hopefully this works. If you can see it, you should be able to click on Zoom.


I was probing around today on the Y Buffer and so Far I have not been able to find a definite short. There are 4 Connectors and the middle 2 seem to be all the same node. Return. The Return of course is an isolated Return. I was able to ID a couple of the IC's on Y Main and traced it over to the buffer board. the 5V Comes from the Buffer Board.

The Freaking Buffer IC's seem to be proprietary to Panasonic and I was not able to find a Pinout on it. It seems that it is some kind of tqfp128-p-1414a package. It would have been nice if I knew what some of the Pins were.

One of the things I want to try is to apply a couple of volts to the regulator and see if one of the IC's get hotter than the others.

I was hoping to find a burnt hole in one of the IC's but nada.





http://i1190.photobucket.com/albums/...ps23c23784.jpg

[smpstech]

Re: Samsung PN50C550G1FXZA

I applied External 5 Volts to the Y Buffer Board and I didn't feel any of the IC's on the Y Buffer Board getting unusually warm. I am now 80% sure the Y Buffer Board is fine. 19mA was being drawn from the Bias supply. So, Either the Display is Kaput or this was just a Y-Main failure.

[tom66]

Re: Samsung PN50C550G1FXZA

The primary power path for the ICs is the Vscan path, about 150V. This is usually what fails short, not the 5V supply.

[smpstech]

Re: Samsung PN50C550G1FXZA

The primary power path for the ICs is the Vscan path, about 150V. This is usually what fails short, not the 5V supply.

Tom, I was hoping to find a bad IC on the buffer board this way. I know the High voltage is what went out. Sometimes the IC House keeping voltage feeds the short on the IC and reveals itself and you have to set the current limit low on your external supply. If I can only get the schematic for he Y Main and the buffer for this TV. But I think I will see God before that happens. :

[smpstech]

Re: Samsung PN50C550G1FXZA

I installed a New Y Main Board and it worked. I ran it for 1 Hour under Load before I declared Success. There simply was no Shorts on the Y Buffer and I just took a shot at it.

I am blaming this one on a Spider. I just bothered me that I couldn't find any schematics on this model. Samsung being so secretive . Remind me not to buy a Samsung anything if they are going to be like that.

[rogerazambuja]

Re: Samsung PN50C550G1FXZA

I installed a New Y Main Board and it worked. I ran it for 1 Hour under Load before I declared Success. There simply was no Shorts on the Y Buffer and I just took a shot at it.

I am blaming this one on a Spider. I just bothered me that I couldn't find any schematics on this model. Samsung being so secretive . Remind me not to buy a Samsung anything if they are going to be like that.

What was the problem of TV, no picture but with sound ok? Because I have a similar Plasma TV (model PL51D550C1GXZD) without picture but with sound ok. I found a short on SMK1360 too, replaced it by a new one but still no picture.