Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

[metaljo2003]

Ok, so my tv cut itself off about two weeks ago and started clicking immediately after. The video worked fine for approximately 2-3 minutes before this happened. I have a background in electronics, so I thought that I would figure this out on my own. HA. Well, I have replaced every board on the back of the tv except the video board. I cannot find any noticeable traces of a destroyed component. When all boards are connected, the relay clicks 5 times and shuts off. With the x-main disconnected to the y-main (they are daisy-chained) the tv powers up without video or backlight. However, the strange thing is that the voltage on the power supply VS is at 11 volts. It should be 207. The VP is at 0 volts. This voltage steadily drops to these from 207 (VS) and 58 (VP).

Now the crazy part, if I disconnect the ribbon cable from the main logic board to the y-main, then the power supply voltage and y-main voltages are correct. Should I connect the y-main and x-main with the ribbon cable unattached, then the tv still will not power on. I'm at a lost on what exactly could is wrong or where to go from here. Anybody else been through this or know where I should start?

[tom66]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Sounds like main board fault.
See:
https://www.badcaps.net/forum/showpo...61&postcount=2

[metaljo2003]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

I will be testing this later on this afternoon and see what it shows. I replaced the board, but it's always possible that the one I received was bad.

[metaljo2003]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

ok. so i unplugged the video input board and shorted pins 3 & 4 from the main logic board. with everything attached, the tv still clicks five times and shuts off.

[capkid]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Odd behavior. I'd try testing some of the Y-main and X-main components with the boards out of the TV. In some of these thin Samsung plasmas, the transistors on the heat sinks will test shorted.

Edit: As you noticed, the Y-main and X-main are chained. Doing a single board swap can sometimes result in a bad board killing a good board, leaving you in an infinite loop of board swaps.

[crt man]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Now the crazy part, if I disconnect the ribbon cable from the main logic board to the y-main, then the power supply voltage and y-main voltages are correct. Should I connect the y-main and x-main with the ribbon cable unattached, then the tv still will not power on. I'm at a lost on what exactly could is wrong or where to go from here. Anybody else been through this or know where I should start?

Hi.
When I disconnected the ribbon to the X main, I killed the Logic board
causing the relay to click four times. See if you have a led on the logic board
and if you have it should flash about once a second anything other you will have probably killed it .

In general what I found was the Y buffer shorted taking out two FET'S the X main replacing these restored the TV back to normal order.

HTH.

Alan.

[metaljo2003]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Hi.
When I disconnected the ribbon to the X main, I killed the Logic board
causing the relay to click four times. See if you have a led on the logic board
and if you have it should flash about once a second anything other you will have probably killed it .

In general what I found was the Y buffer shorted taking out two FET'S the X main replacing these restored the TV back to normal order.

HTH.

Alan.

There is a LED on the logic board that lights up at once per second when the ribbon cable from the y main and logic board is disconnected and the power cable from the y main to the x main is disconnected. When it's all connected normally, it flashes roughly every 5 seconds.

How can I go about testing the FET's?

[crt man]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

There is a LED on the logic board that lights up at once per second when the ribbon cable from the y main and logic board is disconnected and the power cable from the y main to the x main is disconnected. When it's all connected normally, it flashes roughly every 5 seconds.How can I go about testing the FET's?

That was the same as mine, I had to replace it.

You will need a multimeter and check for shorts,
on the FET 's

Alan.

[metaljo2003]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

That was the same as mine, I had to replace it.

You will need a multimeter and check for shorts,
on the FET 's

Alan.

Which had to replace the logic board?

[crt man]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Which had to replace the logic board?

Yes sorry

Alan

[metaljo2003]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

So I am testing the FETs on the x main. Do I put the black lead on the source and red lead on the gate before I swap to the drain to test output? or is it in reverse? If it's not in reverse, I believe I found one bad FET 30G124.

[tom66]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Just test all combinations 1-2 2-3 and 1-3 of each device, using the diode test mode.

[crt man]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Hi,

As you look at the FET put one probe on one outer leg and the other on the other outer leg, and read resistance they should be high if you reverse this then it still should be high.

If they read low resistance any way around then you have a short one.

On my board I had two short FET's caused by faulty Y buffer.

HTH

Alan

[tom66]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

X buffer? Do you mean Y buffer?

[crt man]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Tom

Yes I mean Y buffer that's me not checking my post first.

[metaljo2003]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Should I test these in circuit? I am noticing that most of the FETs on the y main are showing low resistance across the gate and the source (should be the outer legs I believe). There is only 2 of them with low resistance on the x main.

[crt man]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Hi

Yes you can test them still in the board, if there is low
resistance on all combinations of test then these will be bad

1-2 1-3 2-3

I had two fail on the X main but none on the Y main
if you have had most of them fail then you are unlucky.
Alan.

[crt man]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

Hi

You say you replaced the board, compare the readings
on both sets of FET's and see if one of them is a good board.

Alan.

[metaljo2003]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

I looked at the y main and only found one iffy (after testing correctly). It was RFX10TF6S transistor. The drain pin is not in the circuit yet all three pins show a short. I attached a picture of the component.

[metaljo2003]

Re: Samsung PN51D530A3FXZA Plasma Blank Screen W/Sound

i found 5 bad components on one of my x main boards - the original. The other board had 3 shorted FETs. I bought a used y main x main and y buffer off of ebay. Hopefully, this fixes the issue. I will post when they arrive on monday.