Samsung Plasma PN43D430A3DXZA

[clearchris]

Samsung Plasma PN43D430A3DXZA

I'm starting to suspect that I have a bad power supply on this TV or a bad logic board, but I'd like to run it by you guys.

TV is in unknown condition, knd of dirty.
Screen has no sign of damage.
Will display fuzz for a flash upon start.
Clicks when turned on and when plugged in.
No sound on start
No picture on start

Power supply voltages, PS_ON, standby, 5v and 15v lines all test ok on the bench, under no load. VA is at 56v and VS is at 206v, but I don't see the expected voltaged listed on the board anywhere. Again, no load.

I ran the test here with the jumper on pins 3 and 4 and no test patterns (or anything else) were displayed.
https://www.badcaps.net/forum/showth...461#post318461
I checked the test points on the PS for VA and VS and voltage was half what it was on the bench, and going lower as I watched. I assume that was the capacitors discharging. This behavior was seen with the Y (and thus Z) boards plugged in and also with them unplugged.

LED on the logic board has long blinks.

Any ideas of what else I can test?

[clearchris]

Re: Samsung Plasma PN43D430A3DXZA

I hooked an external speaker up to the tuner board, still no sound. I put a tuner board and a logic board on order. Pretty cheap, under $20 for both, shipped. We'll see if that solves it. I'm not entirely convinced it's not the PS, but so far I have no direct evidence to support the bad PS hypothesis.

[ReeceyBurger123]

Re: Samsung Plasma PN43D430A3DXZA

So VS and VA stay up but no image when everything is connected in the TV ? If not check for low resistance across Ysustain VS to ground and also Xsustain VS to ground very common for transistor failures these are, make sure you disconnect the boards from each other though.

[clearchris]

Re: Samsung Plasma PN43D430A3DXZA

So VS and VA stay up but no image when everything is connected in the TV ?

Kind of the opposite. I think that VS and VA turn or for a second or so, just enough to charge the caps, and then turn off. This happens with power connected to X and Y boards AND when power is not connected to X and Y boards. What I see when I measure VA and VS is that the voltage is around halfway of what it should be, and dropping, about 1v per second.

When I have the PS on the bench and jumpered to enable PS_ON and VS_ON, I see proper voltages at the test points.

[tvtimmy]

Re: Samsung Plasma PN43D430A3DXZA

You have a bad x board, seen it dozens of times. Watch a YouTube video of how to check it.

[clearchris]

Re: Samsung Plasma PN43D430A3DXZA

You have a bad x board, seen it dozens of times. Watch a YouTube video of how to check it.

I disconnected power to the x-main, still same behavior. And the tv doesn't keep trying to click on like most of the youtube videos.

[clearchris]

Re: Samsung Plasma PN43D430A3DXZA

Ok, the logic board arrived, tuner board expected to arrive friday. By my reading of how this all works, I think I can:

1. install the logic board
2. completely disconnect the tuner board
3. jump PS_ON on the PS to tuner board connection
4. run the logic board tests by jumping pins 3 and 4 as explained here:
https://www.badcaps.net/forum/showth...461#post318461

I'm somewhat concerned that one board may have fried the other, some I'm hoping to not plug in the suspect tuner board at all for this test. Does this sound like it would work?

[clearchris]

Re: Samsung Plasma PN43D430A3DXZA

Well that was a fail. No difference with the logic board installed.

I did some searching and read about different samsung plasmas, and I figured out some things. There are some samsung "fast track troubleshooting manual" that also seem to be pretty detailed and useful.

So the logic board has an LED on it, and one blink per second means "all good". Five second blink means something is wrong with X or Y. Watching the led while I plug in the box, it blinks for one second a few times, I hear a zapping sound coming from the y-main, and then the 5 second blink comes on. The zapping sound isn't loud, but it's definitely there. Disconnecting the X-main didn't make any difference, so I suspect it's the y-main board.

I also checked Va, Vs, Vsrc and Ve, they all come up to the proper voltage for maybe a second before the power supply shuts down.

I'm going to sleep on it, if anyone has any thoughts I'd love to hear them.