Samsung PN50A510P3FXZA Plasma No Picture

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Good point. Not sure if it's used but it has 0V on it. I am doing the logic board forced operation so everything should be ON.

It's interesting that it would come up to 8.5V from 0 though if VS wasn't being signaled to turn on..?

The PS_ON is turned on by going low on that pin, and is high in standby.

[awyatt2]

Re: Samsung PN50A510P3FXZA Plasma No Picture

ingles and rite aid drugs both carry the battery for the peak, sold as wireless entry battery. last ones I bought were around 5.00 for two in a pack.

[Andrew F. Ali]

Re: Samsung PN50A510P3FXZA Plasma No Picture

No picture means no VS and or VA voltages. PSU not working. Trace the VS circuit and see if any diodes or e-caps are not functioning. Also no VS means no VY and VSC on the Y-Main Bd. How feasible is it for you to get another PSU?

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

A new PSU is on it's way. I have been unable to find issue. I saw some evidence of tampering on the the primary side from previous owner so who knows what was done.

Is there a point feasible location where I can check VS before it gets to the test pins, not sure of how everything works by the big transistors and transformer.

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

The Vs secondary is quite simple, pins 13 & 17 of the transformer connect to DS805 & DS803 dual diodes which connect to CS813 capacitor, DS805 is common anode, DS803 is common cathode. There is also a thin trace from the positive to Rs821 and RS822 for feedback control and over and under voltage sense.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

So is it possible there is a problem on primary side? Any advice on what to check first?

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

The primary does seem to be working, slightly, if it was dead you would not get the 8 volts you do get on the secondary now.
There is a diode labled DS804 near the error board, whats the voltage on it? There is a video that has this board and the led on the error board is flashing, so I think... the steady led could be normal.

What ic's did you replace in the Vs circuit??

[Andrew F. Ali]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Great that you could find a replacement PSU. That will fix your TV. A

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

The primary does seem to be working, slightly, if it was dead you would not get the 8 volts you do get on the secondary now.
There is a diode labled DS804 near the error board, whats the voltage on it?


There is a video that has this board and the led on the error board is flashing, so I think... the steady led could be normal.

What ic's did you replace in the Vs circuit??

5V on DS804.


I replaced the ones included in the shopjimmy kit:

Integrated Circuits 6 UB801, UQ802, 805, US801, UX801, 804
Resistors 2 RS807, RX807
Transistors 4 QS801, 802, QX801, 802
Fuses 3 FB801, FE801, FS803

For some reason did not come with UX805 or those diodes DS803/805 but they appear to be good.

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

That 5volts supplies the feedback ov/uv circuit so thats good

Ok so after changing those parts did anything change from the original problem? Any chance of getting
Any chance of getting a picture of the bottom side VS primary and secondary?

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Nothing changed that I know, I don't know exactly what VS was before I just knew it didn't come up.

Here some pics, let me know if you need closeups in any area. You see some solder work on a lot of areas where I reflowed potential problem areas and pads that came up off the board.

Also you will notice CP809, one of the big primary caps, was circled and unsoldered when I opened up the TV. The pads get damaged easy on this board and I had scrape away some of the board to get to the traces in some areas to fix..

I don't know why, and I'm pretty sure I checked early on and have 395V there..

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Are you sure the center pin of DS805 is connected to the CS813, it does'nt look like it is in the picture

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Yes it's got a good connection that's just the lighting..

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Above US801 in the 2nd pic there are 4 transistors (?) (QS803>806), I can't be sure but it looked like maybe the solder had been changed on those.. Nothing is shorted I just know what someone did before..

I hope to be able to use the new board to figure out what's wrong on this one.

Where is the first point I should have the +-200V for VS? Anything I can check on the primary side of that circuit?

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

The secondary could not be simpler. What you could check is the voltage across the optocoupler, pins 1 & 2 (they are on the secondary) then check the voltage across pins 3&4.
If you want you should be able to compare the voltages on UX801 and US801, see if there is a pin that is different, remember this is using hot ground
The transistors are part of the drive circuit for the fets, the drive output A & B come from the ic, go through the 2 transistors and drive the gate drive transformer.
Usually if there is a problem with the drive circuit it blows the fets.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

This ICS801, if you're talking about voltage across each both pins on the secondary side, and then both on the primary side, it seems it's 0V on both.

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Well thats not right, I wonder if the opto is bad, check the resistance between 1 & 2 and then 3 & 4, you can compair the readings to icx801

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

From some other information I found on the alarm board is (I believe) a steady green led means standby voltage is there and ok. if that led was blinking, it would blink the error.

Another thing to try would be unplug cn802 and using a 1k resistor jump 5 volt standby (I believe it is JP131, check it to be sure) to Vs_on and see if that turns on the Vs.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

New Development

Got another PS board. Same exact issue, 8.5V on VS.

Fantastic.

Will check VS_ON next...

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

I'm not sure what VS_ON is supposed to do it's between 0 and 1V whether on or off. Is it possible logic board is problem?