SAMSUNG Plasma PS51D450 no power

[brunomalone]

Hello. I need help trying to fix my TV. It just stopped working suddenly while watching it and, since then, all I have when I plug it is the relay click and red led flashing 6 times. That's all, no image, no sound, no red led, although the red led flashes when I use the remote control. The logic board's green led flashes 5 sec on /2 sec off, which, according to the service manual, means DRV_RESET (no idea what that means). There is not voltage in Va and Vs. Never, not even for a second right after plugging the tv. However the voltages are correct in the flat cable that goes from the PSU to the main board.

I have tested all the capacitor (they all look ok) for capacity and ESR and they are fine.

So far, that's what I've done. What would be the next logical step?

According to what I've read on this forum and I've seen on youtube I think I would have to use jumpers between pins in the connector that goes to the mainboard and try to force the backlight, but probably I'm wrong.

l'm not a technician and my English is limited, but any help is greatly appreciated. Thanks in advance.

[tom66]

Re: SAMSUNG Plasma PS51D450 no power

Is the panel free of cracks? This model has an issue with spontaneous panel cracking.

[brunomalone]

Re: SAMSUNG Plasma PS51D450 no power

That was quick! Thank you! I have carefully inspected the panel with a flashlight and I have not found anything unusual. How big is what we would be looking for?

Apart from that, when I plug the TV, besides the click of the relay, a noise is heard in the center of the PSU. I've uploaded to SoundCloud.
https://soundcloud.com/user-49801249...0150920-164622

[tom66]

Re: SAMSUNG Plasma PS51D450 no power

OK, usually the crack is somewhere in the middle, about an inch or so across, but you should be OK if there's nothing visible.

That ticking sound indicates a Y or X main short. Disconnect the Y and X main from the TV. If you have the boot melody enabled, it should now play; if not, connect a source and you should hear sound when you press the INPUT button on the set. Also, if you check Vs and Va they should appear briefly (5 seconds max) when turned on, the control board will however turn them off as it detects a fault so they will drop to zero quickly.

[brunomalone]

Re: SAMSUNG Plasma PS51D450 no power

Thank you. I've disconnected the Y-main (the X-main is fed through the Y-main) and Va and Vs appear briefly as you've explained. However, I can not hear any sound (I've never had the melody boot enabled). I've tried using the "source" button (is this the same as "input"?) but I do not get any sound. The ticking sound is still there, btw.

[tom66]

Re: SAMSUNG Plasma PS51D450 no power

OK, using your meter please check and see if the 5V and 13V from the PSU are ok.

[brunomalone]

Re: SAMSUNG Plasma PS51D450 no power

I can find 5 volts and 15 volts (instead of 13) on all pins of the PSU where they are supposed to be.

[tom66]

Re: SAMSUNG Plasma PS51D450 no power

OK, I would try connecting just the Y-main, see if the Vs/Va still rise. If not, it is the Y-main that is shorted. If it works, then connect the X-main to the Y-main and check again.

[brunomalone]

Re: SAMSUNG Plasma PS51D450 no power

With just Y-main connected Vs/Va do not rise. I'll try to find a Y-main on the internet. I think I remember reading here that it was desirable to replace them in pairs ( y-sus + y-buffer). Is this also true for this model?
Thanks very much for everything. I'll update the thread once the circuit has been replaced.

[brunomalone]

Re: SAMSUNG Plasma PS51D450 no power

I am learning electronics while trying to repair the TV, so I'll probably say something very wrong, but testing the Y-SUS I detected something that seems suspicious to me.
As you can see in the accompanying pictures, in the Y-SUS there are 3 large blue capacitors in parallel (150uF 250v). My intuition tells me that these two wide tracks that they are soldered to should not be shorted, but they are.
Is that normal?

[marty_cam]

Re: SAMSUNG Plasma PS51D450 no power

Hi. I'm having Similar problem with the same set. What I've noticed is that when I apply power, the picture briefly illuminates (white noise, when not tuned) and then screen goes completely blank. the Red light flashes 6 times and goes out.... I do get the initial click as previously mentioned..

Anyone any suggestions? btw, I'm not a qualified repair man, although I have rescued many sets by replacing capacitors etc on PSU's etc. What are the boards mentioned in the previous solution(s)... x/y main / sus etc

Can someone show me a pic of which board is which?

best regards

[marty_cam]

Re: SAMSUNG Plasma PS51D450 no power

here is a picture of the back of TV... Can someone show me which board is x / y etc and I could probably begin assessing what is going on with it....

[Hamie]

Re: SAMSUNG Plasma PS51D450 no power

Y-sustain to the left.

X-main (z-sus) to the right.

Disconnect the harness that connects the power supply to the to y-sus and check vs and va voltages.

[marty_cam]

Re: SAMSUNG Plasma PS51D450 no power

Thanks Hamie.

Would I be right to assume I should be getting 5v and 13/15v??

thanks again, hopefully I'll get to the bottom of this.

[brunomalone]

Re: SAMSUNG Plasma PS51D450 no power

Hi. After trying to repair the shorted Y-sus for a few months I finally decide to buy a second hand Y-sus board. The TV works perfectly again. Thanks tom66!