PN50B400P3D 50" Samsung Plasma Won't Turn On.

[capkid]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

Ok. I'd try pulling the Y-main and X-main boards and doing some tests on the components. I like to check some of the heat sink components on these Samsungs to see if any of the transistors or diodes have failed:

https://www.badcaps.net/forum/showpo...2&postcount=11

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

Ok, I pulled all the boards. I checked all the transistors & diodes. I'm not sure what exact readings I'm looking for but they all read about the same, .500 in one or two directions & open on the others, with a few exceptions. The only thing that seemed usual is Q5304 the first transistor on the top right heat sink of the Y main read OL in all directions. Q5501 also from the Y main read (pin count from the top of the board, first number positive, second negative)1-2 OL, 1-3 1.8, 2-1 OL, 2-3 OL, 3-2 .580, 3-1.937. These readings were above everything else.

This is on the Y main, it looks like it has been warm ( board is discolored on the top) but seemed to read ok.


I cleaned some dirt of the back of the boards. and put it back together


Plugged it in & no change. I started programing codes into a universal remote & got it to turn on finally. The screen flashed zig zagged white for a split second then went black. I have sound & the power light flickers red.

So as of now, I have sound but no picture & it's not responding to the side control buttons.

[tom66]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

I'd try the self test again on the control board if you're getting some light from the panel.

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

Alright, I tried the self test again. It turns on by it's self now, it does the samsung sounds & then audio from my movie. No change in the picture. The power light on the front blinks for about 10 seconds then goes out. I reconnected the LVDS cable, removed the jumper, plugged the TV back in & it acts the exact same way as it did while preforming the control board test.

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

tom66, capkid, Whats your gut calls? I don't like throwing parts at something, at the same time, I have $40 in this project. I also have a good understanding of percentages & odds, that's why I find myself in this situation.

[tom66]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

White flicker usually means the control board has started trying to initialise the plasma panel but failed. This can be either Y-main or X-main. The buffer is usually good if you see a flicker. It's recommended to replace both Y- and X-main boards simultaneously due to how they share an energy recovery circuit. Repair of these boards, whilst not impossible, is unlikely to be economically sensible. The boards are available cheap.

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

Thanks Tom, I've checked around ebay, shopjimmy, etc... and can find a Xmain for about $35 but the cheapest Y-main(BN96-12390A) is about $100, if it's in stock. Is that about normal?

[tom66]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

Are you searching LJ4..... number or PN50B400?

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

I was using BN96-12390A & LJ92-01689A. I've just tried LJ41-07016A, still nothing under $100 in stock. A lot of stores list them anywhere from 50-70 but its out of stock.

[tom66]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

If it helps that is a clue that board is a common fault.

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

I suppose so . I'll watch for one to show up for a little less for a while & then post back when I put some new boards in it. Thanks for the all the advice.

[capkid]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

That's an expensive Y-main for one of these thin Samsungs. Since you mentioned $100, I'm assuming you saw this one: http://www.ebay.com/itm/Samsung-LJ92...item43bfdc7113

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

Yeah, I will give it to him that it's about the only one available on the internet right now but I'll wait a week or two & see what shows up.

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

I've got new X & Y mains today. The X main numbers match exactly, the Y-main matches except for the PBA Rev. The old one is AA2, the new one is AA3. The Rev No matches R1.3. Will the new one work?

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

[tom66]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

That should be fine.

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

Well, I replaced the X & Y-mains with factory new boards & no change. The tv still turns on, flashes static with pink around the edges for a second & then blank with sound. I tried the control board test again with the same results.What else could it be? Thanks

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

Plasma panel? Power supply board? Buffers? How do you tell if it's a bad plasma panel? That's the only thing that concerns me, I can replace about every other board & break even on the project.

[tom66]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

A panel that lights up repeatedly is not cracked so not bad (excluding vertical bar problems, but that wouldn't stop a picture from appearing.)
I would try checking the -Vsc and Ve voltages.

[Dowd, Elwood P.]

Re: PN50B400P3D 50" Samsung Plasma Won't Turn On.

My meter is set at 200v DCV
VE is to be a 89. VE reads 89 for 4 seconds & then starts to drop. VSC is to be -193. It does not read at all(0.00). I tried it 4 times with meter in place before plugging the TV in.

while I was at it I checked Va & Vs on the PSB
VA to be 55 Vs to be 209
They both read their correct values on initial start up but jump around quite a bit & start to fall after 1 second or so.