X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

[chico1st]

Has anyone successfully repaired a X-Main (LJ41-07015A) from a Samsung Plasma PN50B400P3D.

I had no power on my TV and a clicking relay and I have narrowed it down to this board.

If anyone has repaired one before, has a schematic it would be useful or know general issues with 2009 ish Samsung Plasma TVs.

I attached an image of the board from shop Jimmy.

[ReeceyBurger123]

Re: X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

Do you have a DMM and know how to check for S/C aka short circuit ?

[chico1st]

Re: X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

Yeah I have a multimeter and know how to use it.
I havent started pulling parts off yet.
Repairing parts in unknown schematics is new to me though. I assume I basically need to pull everything off to check them but I was hoping to know where to focus my efforts.
This is what i know so far:
-The chassis ground seems to be pretty much shorted to Vs (it has a bunch of 150uF 250V electolytic caps between it and chassis ground)
- The Vs rail also goes to the collector of some IGBT (RJP30E2DPP-M0) Q4301
-The gate of that IGBT goes so a rail that is connector to every pin of the 'HD' connector and every pin of the buffer board connector). This rail is also shorted to ground.

[chico1st]

Re: X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

Also worth mentioning came to the conclusion that I was the X-main board by just plugging and unplugging the internal boards using the start up chimes as a sign that it was working.
the X buffer may be broken too...or whatever the 'HD' connector goes to but unplugging them and leaving x-main attached still resulted in no power and a clicking relay.

[chico1st]

Re: X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

I successfully repaired this board. I wanted to change the title to be the PCB ASSY number instead of the PCB bare board number. Is there a way to update the title?
Then I will just dump my repair notes into this thread.

[chico1st]

Re: X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

OK the failure for this seemed to be a blown fet in the pull of the push pull driver which blew all the fets in the push pull and the driven impedance matching circuit (which goes to net ERC but I have no idea what that is).

In general i replace R4502 and R4102 with 15 ohm resistors since they were tied to Vcc in the failed condition and blew. Luckily the SO233 parts near it were fine.

I also replaced the four 360V push pull IGBTs with FGPF4536 since the originals were obsolete.
Q4302,Q4301,Q401,Q4014

The 2 IGBTs on the impedance matched driver with FGPF4533
I forget the component numbers but they were the only two 3 legged through hole ICs near C4505 and C4506.


The PCBA# for this board was LJ92-01727A and the LJ41# i referenced in the title was just the # for the bare board.

[Alastair E]

Re: X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

X-SUS is 'H' Bridge, (Not push-pull) with other stuff like ERC circuit...

[chico1st]

Re: X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

Hmm fair,
I have no idea what the ERC is connected to since it seems to not connect to anything on the X main and thats the only circuit i looked through. A lot of the power seems to travel to the Y main. What does the ERC control? A general current to the plasma? Why would you need to H bridge it, can plasma go backwards?

[masaudio]

Re: X-Main (LJ41-07015A) repair on my Samsung Plasma PN50B400P3D

Just done the same board..

Replaced similar parts plus a few others..

The 2 surface mount resistors, R4102, R4502, 15 ohm.
D4103, D4302 STTH1004FP
Q4503, Q4504 30F123
D4202, D4505, D4901 RF1501
Q4101, Q4104, Q4201, Q4301, Q4302 RJP30E2

Thanks, Mark.