PN50B400P3D 50" Samsung Plasma Won't Turn On.

[Dowd, Elwood P.]

Hello, This is my first tv repair project. I've done some research but nothing seems to match up with this issue. I bought this TV with the information that "It was working fine and then the picture went black but it has great sound". It came with no remote. I plugged it in, it goes "click click....*3secondpause* click click" with a constant red power light. I've tried tapping, "pushing", & "pushing" and holding the power button, no change. I've disconnected the power supply from the X main, Y Main, & both and and tried to turn it on & no change. I had a live RCA video and audio input while testing. No sound or video, just a solid red light. There looks to be no obvious bad, bulged capacitors. Here are pictures of the back of the tv, X, Y, power boards & my voltmeter. Whats the next step? If I need to get a reading, please tell me where to put the leads & what setting my meter should be on. Thanks.

MODEL NO:PN50B400P3D
Model Code: PN50B400P3DXZA
MFD: Nov 2009
Version: LU04

[capkid]

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

You might want to try this: https://www.badcaps.net/forum/showpo...61&postcount=2

[Dowd, Elwood P.]

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

Thanks capkid, I believe this is my control board (see below) I've identified the 4 pin connector & the pin's are labeled, I however do not know which cable is the LVDS cable? Mine does not appear to be the same as shown in that thread & the cables looks similar to my untrained eye.

[capkid]

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

The LVDS cable is the one at the top of the control board.

[Dowd, Elwood P.]

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

Thanks! Below is how I tested it, with a live video feed & no change.

[bigclown187]

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

Does the green light come on at all when you press power or is it always red? I just fixed a COBY LCD that would turn green then back to red. It was just a single bad capacitor that I replaced and it is as good as new.

[bigclown187]

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

I forgot to say that in my experience a capacitor does not have to look bad or bulged to be bad or not at full capacity. I would definitely check them with your multimeter.

[Dowd, Elwood P.]

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

The light in front never turns green, it blinks once 1 second after being plugged in & then stays solid red. There is a green light on the control board that comes on for 6seconds or so in between the clicks. What setting should my meter be set on to check them? Thanks

[capkid]

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

It's possible, but I highly doubt you have bad caps in this TV. A lot of these newer Samsungs are not known for having cap problems, since Samsungs were notorious for having bad caps in earlier models; they've since corrected a lot of those issues.

Did you try disconnecting the Y-buffer from the Y-main, leaving the Y-main and X-main connected to the power supply? Warning: When you go to reconnect the Y-main to the Y-buffer after this test, you need to monitor the voltages at the Y-main connector or you'll see a spark if the voltage is too high when you try to reconnect the two. I usually wait for the voltage to drop below 1V, or I discharge the caps on the Y-main. You can potentially cause damage if you don't wait for the voltage to drop.

[Dowd, Elwood P.]

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

I haven't tried that. If I leave the tv unplugged for 15 minutes before reconnecting the Y-buffer, will that eliminate the chance for damage?

[capkid]

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

I haven't tried that. If I leave the tv unplugged for 15 minutes before reconnecting the Y-buffer, will that eliminate the chance for damage?

It could, but I'd still do a voltage check to be on the safe side.

Edit: It might be a good idea to disconnect the X-main from the panel at the same time.

[Dowd, Elwood P.]

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

ok thanks, I'll give it a try.

[Dowd, Elwood P.]

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

Just to be certain, which one is the Y-buffer? There seems to be a buffer boar on the left side & on the bottom. The board on the bottom was un plugged when I got the tv, I plugged it in but no change. I unplugged it for the rest of my testing.

[capkid]

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

The Y-buffer is the long, vertical board on the far left when you're looking at the TV from the back. Which board specifically has been unplugged while you've been testing?

[Dowd, Elwood P.]

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

This is the board that has been unplugged. it runs the entire length of the TV on the bottom.

[capkid]

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

Ok, I don't think it will make much of a difference, but I'd plug it back in anyway.

[Dowd, Elwood P.]

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

There looks to be 4 connectors for the Y-buffer. Would I just check one for voltage before reconnecting?

[capkid]

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

It wouldn't hurt to check all four. If I remember correctly, checking one is a good indicator.

[tom66]

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

Just remember with the long bottom board do not plug in while live.

[Dowd, Elwood P.]

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

I plugged in the bottom board, disconnected the Y-buffer, plugged the tv in & no change.