Samsung PN50B450B1DXZA X-main keeps blowing

[Nick's Tvs]

I got a samsung PN50B450B1DXZA that came in the shop with a shorted X.
X-main part number is BN96-09736A (LJ92-01600A) I replaced the 4 IGBT's location numbers Q4004, Q4005, Q4007,Q4008 with part number RJH3044 that were all shorted. I took some readings and found that they have 10kohms between the 2 outer pins from a 10k resistor, and about 78Kohms and 88kohms from middle leg to the outer legs. That seemed low to me, so I went on a multi hour search for something that could be lowering the ohms value but didn't find any faulty components.
I plugged the X main back in and made sure the panel was disconnected. The voltages all seemed good through the board, and I had about 84 volts on ve aka the lines going to the panel.
I turn the tv off, make sure the power supply clicks off, unplug it, wait a bit, plug the panel in, and boot it up. Fizzing/loud sounding discharge coming from that Xmain area of the set, and pop. IGBT's all short to ground. At this point, I think bad Panel. However when I redid the xmain repair, I did the same thing and didn't plug in the panel, so the tv stays on and you can see a partial crappy shadowy picture which makes me thing panel is ok.
What do you guys think is going on.
I very very rarely come across a bad panel, so I am hesitant to call it bad.

Let me know if you need additional pics.

[ReeceyBurger123]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Nick my friend, this Tv chains the ERC between the Y and Xmain boards meaning that a bad Y can kill the X m. Check the Y for S/C on the power fets.

[Nick's Tvs]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Reecey, thanks for the reply.

I have hear a bad Y can kill an X but have never seen it in person yet so it didn't come to mind to check for it. I will go ahead and check that right now.
The set does show partial picture on screen with the X disconnected from panel however, so I would assume the Y is ok. Ill check either way however. No loss in being thorough.

[Nick's Tvs]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

no shorts, most had about 80kohm and the large fets were much higher.
Any other suggestions or parts to check?

[Nick's Tvs]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

I still haven't been able to figure this out, and I would rather not toss it up to a bad panel. Does anyone have any last check they can think of?
Remember, I checked the X-main for hours for any bad components took many out of circuit, but never found anything bad aside from the 4 IGBT's that keep blowing, and I do get about 80v going to the panel when the panel is disconnected. The board keeps popping as soon as the panel is connected and turned on. However when the panel is disconnected on the X main side, I get shadowy crappy picture on the screen which makes me think the panel is actually ok.

[ReeceyBurger123]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Doubt its a bad panel thats VERY VERY rare on Plasmas, there is not much to go wrong inside them. Your missing something somewhere. The Tv should work with the Xmain disconnected you will get image with it out and on just distorted. Have you tried doing that ?

[tech2014]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Did you replace the gate driver ICs that control the shorted IGBTs? If not that will cause your new parts to blow.

[Nick's Tvs]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Reecey burger

yeah I do get a bad picture with the xmain disconnected.

I have not tried checking the IC that control the shorted IGBT's but as stated earlier, with the panel disconnected from the Xmain but the Xmain still in circuit, I get 80 volts going to the panel, wouldn't that tell us the X-main is ok?
I would like to check this IC you are talking about however, do you know what the location ID is for the IC?
Thanks guys appreciate all the help!

[ReeceyBurger123]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

The Xmain wont be working though when its not connected to the Pdp as it wont be sustaining the panel there for the fets wont run. Check the driver Ic's and other related parts Ie Zener diodes and resistors.

[ReeceyBurger123]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Any update Nick ? I have the same Tv here same failed fets on Xmain nothing else tests bad so going to replace them.

[Alastair E]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Prolly summit to do with the ERC circuit on the Y causing the X damage...

Happens with these cross-connected single ERC systems--Panasonic is just the same, X kills Y or Y kills X....

[ReeceyBurger123]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Yep I have checked out my Ymain nothing shorted but im replacing a couple of fets which commonly blow on it too. Im doing a vid so will upload when done

[jellytot]

Re: Samsung PN50B450B1DXZA X-main keeps blowing

Hi Reecey, Nick, did you guys ever fix your x-sus fault ? I have the very same thing happening on a PS50B451B2WXXU.