Samsung PN50A510P3FXZA Plasma No Picture

[kevinm34232]

It's been a while since I worked on these... TV turns on and off normally (I assume I'd have sound), no screen glow at all. No VS voltage, VA is good.

I have bypassed main board, forcing PS on with test pattern process and nothing.

I have disconnected connectors to X and Y Main and still no VS. There is nothing obvious burned or shorted on the PS. I can't seem to find a SM either.

Anyone familiar with these?? Thank you.

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Did you check for a short on the Vs line? Does the Vs voltage come up then drop off right after powering on? Most power supplies would need a load on the Vs line to test as they usually have Over Voltage Protection.
You did check the power supply FS803 fuse correct?

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Ya the fuse is good and there is no short... It doesn't come up at all, 8V max...

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Check the connections on the output diodes like DS803 & Ds805, also check if DS803 or DS805 are ok and not shorted

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Should I be getting VS with X and Y disconnected?

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

You may not get Vs with no load, You can use two 60w 120volt incandescent lamps in series connected to the power supply Vs and ground, if the Vs comes up it will light the lamps

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Well even with everything including Y and X main connected, VS doesn't go above 8V. Everything but VS seems to be good, 395V at main caps. None of the transistors or diodes I can find or that are in shopjimmy repair kit are shorted, unless it's one of the ICs but nothing is obviously showing bad or shorted.

Anyone have a schematic of the this board (BN44-00222A) and can help tracing the VS line?

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Apparently there's this alarm board on this PS, I don't see it flashing a code or anything.. Not sure what to look for... Frustrating that there is no readily available info on a 10+ year old TV.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Replaced a few of the ICs on VS circuit, VS still won't come up. Is it possible big transistors QS801/802 are bad even if not showing shorted? I have new ones but they'll be a hassle to change out..

[maxvalutech]

Re: Samsung PN50A510P3FXZA Plasma No Picture

May help PN series covered

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Did you check if the fuses on the Ysus and Xsus boards? including the small green F5006 on the ysus and F4000 on the xsus
If you have a capacitor tester, check CS810 & CS811 Square blue caps on the power supply, if not have a good look at them, see if they look bulged or are nice and square.
Are ther any led's lit on the alarm board?

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

The fuses are all good, and the caps visually look OK.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

How do I tell about the alarm board? There is just one steady LED lit green on it, I don't see any way to determine what that means? Everything else seems to be good, minus the VS which just gives a steady 8.5V. I replaced almost everything in the shopjimmy repair kit..

Did you check if the fuses on the Ysus and Xsus boards? including the small green F5006 on the ysus and F4000 on the xsus
If you have a capacitor tester, check CS810 & CS811 Square blue caps on the power supply, if not have a good look at them, see if they look bulged or are nice and square.
Are ther any led's lit on the alarm board?

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

If you are getting 8.5v it looks like that supply is trying to work, since you don't have a cap checker.
Why don't you try switching one of the blue caps, either cs811 or cs810 and switch it with CX810, and see if the Vs comes up

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

I have a cap ESR meter I haven't used it in years I'll try to find it..

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

I guess give it a try. I could'nt find any information on the error board al001, I suspect it just means there is a problem, in this case low/no Vs

Did you ever check RS807, Its a white ceramic resistor near fs803 fuse

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Ya I don't have the 12V battery this thing requires anyway and it's low... I mean it is a capacitance meter as well but I haven't used it much.

What kind of tool would I use otherwise?

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Like I said you could swap the one from the va circuit with one of the ones in the Vs circuit just to see if it makes a difference. What kind of tool? a working capacitance meter, a scope, another 47n/1250 cap...
I saw a resistor that should be checked, its RS807 near FS803 fuse

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma No Picture

Tried swapping CS810 and CX810, same result. RS807=good.

I appreciate the help R_J.

I ordered another board we'll see if that does it. Thanks again!

[R_J]

Re: Samsung PN50A510P3FXZA Plasma No Picture

I just had a closer look at CN802 and there is a Vs_ON pin, did you ever check the voltage on that pin?

It seems UQ805 ic supplies the VCC for the Vs controller chip, is there voltage on its in and out pins (input pin is JP104) output or ic vcc is on JP26