Samsung PN50A510P3FXZA Plasma

[kevinm34232]

This TV had the symptom of cycling on and off like the last one of these models I got.

I replaced a faulty cap on the main board and the TV now comes on with sound, however there is no picture and no screen glow.

The owner just described the cycling issue that got worse until it took 2 hours to finally come on.

I have good Va and Vs voltage at the Y and Z main. No blown fuses or anything. What can I test next? I tried the test pattern test and no glow and picture. I don't see any crack in the screen or anything from possible damage in transport.

Thanks!

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

Here's a quick overview of the layout. Is there a chance something bad on Y-Main yet still have good voltages and no shutdown?

[tom66]

Re: Samsung PN50A510P3FXZA Plasma

Try checking -Vsc voltage on Y-main, Ve on X-main. Is control board LED blinking steadily?

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

Vsc = -195v
Ve = 96v

both good per sticker.
2 LEDs on control board blink steadily.

[tom66]

Re: Samsung PN50A510P3FXZA Plasma

Check voltage across these capacitors on X- and Y-main board. Only need to check one of each group.
Should be 65~135V. A little higher or lower may be OK.

If it tests low on Y-main/X-main: check +15V fuse
If it tests high on either board: bad X-/Y-main

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

Tom I get about 108V across these caps.

[tom66]

Re: Samsung PN50A510P3FXZA Plasma

Hmm, bad buffer board or panel then.
Sure about no black glow? Could be very dark... check in dark room...

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

Nope no glow. Here's what the seller said. They had this issue with the TV cycling on and off until it finally came on, due to the bad SMD capacitor on the main board.

They decided eventually to just leave the TV on all the time, and just shut off the cable box. This worked for a few weeks they said until they had a power outage, then the TV didn't come back on.

So I'm wondering if the power outage/surge killed something else? Does this help? I do not see any cracks in the glass or anything and no buzzing noise.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

Which components if bad could cause the screen not to glow:
Y-Main
X-Main
Logic Board

[tom66]

Re: Samsung PN50A510P3FXZA Plasma

Y-Main
Buffer
Logic
X-Main
Panel

in that order, from my experience.

Do you have a scope?

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

No I don't. Is that what I need to troubleshoot any further?

[tom66]

Re: Samsung PN50A510P3FXZA Plasma

Generally yes I'd recommend a scope.
Check all fuses on Y-main such as those for the 15V and 5V.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

All the fuses are good, there is one glass fuse and several of the green thru-hole fuses that are fine. I may try a new Y-Main.

[tom66]

Re: Samsung PN50A510P3FXZA Plasma

Check PSU voltages for 15v and 5v. I can't recall if 5v is generated on control board or not.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

OK, I will double check later when I get home but I think I had them (It may have been 5 and 18V). Are these voltages going to the Ysus or control board or both?

[tom66]

Re: Samsung PN50A510P3FXZA Plasma

15V/18V goes to Y-main / X-main directly usually. 5V is fed in by control board. Usually.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

Ok Yes the 15V and 5V are present unfortunately.

I've ordered a logic and a Y-Main pretty cheap, and hopefully one of them will fix it, will let you know. Thanks for the help on this one. It was disappointing, thought it would be a simple fix with the main board cap which was bad first.

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

Update on this one:

Got replacement logic board first, same problem no glow or picture.

Got replacement Y-Main today. TV works. What do you know, looking at bottom of original Y-Main, one capacitor had been obviously "replaced" with the wrong value cap and a horrible solder job. I will try replacing that cap and see what happens.

Mystery solved thanks to not getting the truth in the first place!

EDIT: (2 caps had been replaced). Funny thing is one of those caps on the new board is bulged, great..

[kevinm34232]

Re: Samsung PN50A510P3FXZA Plasma

No repairing of old Y-Main, some pads were torn and after attempt to repair resulted in something burning on it.

Anyway TV is repaired for around $25. Thanks for T/S'ing help Tom.