Samsung PN51D550C1F X main problem

[tech2014]

This tv would keep clicking when the power was applied. I found that when I remove the connector going from the XSUS board to the YSUS board, the voltages would all stay on. I found 4 shorted IGBT transistors on the X main. I replaced all of them and I even replaced all of the gate drive ICs. I connected everything except for the ribbon cable going from the control board to the XSUS. The power came on and all the voltages were present, VE, VSCAN, VS and VA. I then connected the ribbon cable going from the control board to the XSUS. I turned the power on and there was a pop and I found that all the IGBTs are shorted again. What the hell?? Worked fine until the ribbon is connected?

Any idea what caused this??

See pics below. One of the pics is for the ribbon cable that goes from the control board to the XSUS.

[tech2014]

Re: Samsung PN51D550C1F X main problem

I found a place that sells this board. Would it be better to just order the board rather then try and rebuild the failed one.

[tech2014]

Re: Samsung PN51D550C1F X main problem

anyone know what I may have missed???

[ReeceyBurger123]

Re: Samsung PN51D550C1F X main problem

On these sets the Ybuffer and Ymain can kill the Xmain due to them using combined ERC, have you checked for S/C on them ?

[tech2014]

Re: Samsung PN51D550C1F X main problem

yup, all good. Thats why I'm confused as to why the X main blew again. I had the Ymain and Xmain boards connected together and all the voltages were fine. The board didn't pop until I connected the ribbon cable from the control board to the Xmain.

[tw2005]

Re: Samsung PN51D550C1F X main problem

Sounds like it may need a triple bypass.

seems to be a common thing with these from what I've read of people tackling just the xmain.

Attempted a 42" some time ago now, repaired the X, ended up with bad X & Y ,
replaced x,y and Y buffer together and working again. Firmware updated.

Boards were plentiful and cheap at the time, not now.

[Nick's Tvs]

Re: Samsung PN51D550C1F X main problem

Tech 2014
I have had the same issue as you, replaced 4 IGBT's but there were also a few other transistors shorted out as well. I think it was a total of 6 or 8 on the board. Did you make sure to check every single component screwed into the heat sinks?
Also want to point out that I have performed a repair very similar to what you have done and a couple of the transistors popped. Replaced them again, plugged it back in and the board has been working fine since a month ago. I don't know why but I just had a funny feeling one of the transistors I had replaced might have just been faulty out of the bag. Very very low probability of this actually being the case, but just saying, it happens.

[tech2014]

Re: Samsung PN51D550C1F X main problem

Tech 2014
I have had the same issue as you, replaced 4 IGBT's but there were also a few other transistors shorted out as well. I think it was a total of 6 or 8 on the board. Did you make sure to check every single component screwed into the heat sinks?
Also want to point out that I have performed a repair very similar to what you have done and a couple of the transistors popped. Replaced them again, plugged it back in and the board has been working fine since a month ago. I don't know why but I just had a funny feeling one of the transistors I had replaced might have just been faulty out of the bag. Very very low probability of this actually being the case, but just saying, it happens.

I actually had a brain fart. I forgot to install the screws on the board. After the repair, I just installed it and turned the power on. Would this damage the new parts?

[Nick's Tvs]

Re: Samsung PN51D550C1F X main problem

That I don't have enough experience with this specific board to know, I can tell you however that with other sustain boards not screwing in all screws will cause IGBT's to blow. I don't know how this board is designed and I don't have the tv or the board anymore so I can't really check. On the other sets however, if you don't screw in all screws, one or 2 of the IGBT's usually will blow short so you should be able to check the ones your replaced for shorts and go from there.
good luck.

[johnboy1313]

Re: Samsung PN51D550C1F X main problem

I actually had a brain fart. I forgot to install the screws on the board. After the repair, I just installed it and turned the power on. Would this damage the new parts?

Yes, I did the same thing a month or so ago with the same board in the same set and it popped immediately. I had to order more IGBTs, so I buttoned it up and haven't looked at it again.

[mmartell]

Re: Samsung PN51D550C1F X main problem

Keep in mind the ribbon supplies the waveform and without it I don't think the x does any switching so it doesn't really tell you anything. Check if any low ohm power resistors on the xmain have gone open - though I don't know if that in itself would cause the igbt's to blow.

[RCA2000]

Re: Samsung PN51D550C1F X main problem

I have to warn you all...when these were NEW a few years BACK..I saw a few of this problem. It turned out to be bad PANELS...that would zap ANY new X main boards INSTANTLY.. You could replace ALL boards--and STILL ZAP at prime !!

[Alastair E]

Re: Samsung PN51D550C1F X main problem

I have to warn you all...when these were NEW a few years BACK..I saw a few of this problem. It turned out to be bad PANELS...that would zap ANY new X main boards INSTANTLY.. You could replace ALL boards--and STILL ZAP at prime !!

The D Series always was crap and age has just made a crap set--Worse!

E series is the same! Cheap Samsung Crap.

Even when you get 'em working--The panel has generally aged and gives terrible mal-discharge that's incurable....