Dead Samsung Plasm needs Help

[bwilliams60]

Good Afternoon,
I acquired a Samsung P42H-2 Plasma Display unit from one of my students in "unknown" condition. I took in home, plugged it in and ... it's black. No picture, no sound and only a faint hint of backlight. I plugged in my laptop and went to Youtube and hooked it up to the TV. Played any video and still, no picture, no sound. Messed with source button and menu, volume etc. no change.
Diagnostics:
1) Green light on at front of TV
2)Remove cover - logic board LED flashing constant
3)Check voltages on power supply Vc = 55.3 VDC (spec 55VDC), Vs = 205.6VDC (spec 207 VDC), Vg = 14.9VDC and D5.3 = 5.2VDC
4)Disconnect Y-SUS board - no change - reconnect board
5)Disconnect Z-SUS board - no change
6) Start scratching head

This unit has a lot of dust in it as you can see. No caps look bulged and I just got my new Blue ESR meter kit in so I have to put it together before I can test them. Where to start?

Any thoughts?

[Hamie]

Re: Dead Samsung Plasm needs Help

Can you take a close up picture of the 'control board'

(Small green board below the power supply)

[bwilliams60]

Re: Dead Samsung Plasm needs Help

I wasn't sure which board you wanted, main or logic so I have both attached. What are we looking for?

[Hamie]

Re: Dead Samsung Plasm needs Help

Ok disconnect the LVDS cable that connects the control board to the main av board.
The one with the blue plastic tab here.



Then on the little black square with 4 pins sticking up located here.
Connect pins 3 and 4 with a crocodile clip/piece of wire etc



Let me know if test patterns appear on screen.

[bwilliams60]

Re: Dead Samsung Plasm needs Help

Okay I did as you said and there is no change. No picture, no test screen, just blackness.

[Hamie]

Re: Dead Samsung Plasm needs Help

Ok you'll need to check voltages on the sustain boards.
First of all, does the control board LED flash like a heart beat or once every six seconds?

[bwilliams60]

Re: Dead Samsung Plasm needs Help

It is like a heartbeat. Steady at about 1 beat per second.
As we go, can you explain why I am doing what I am doing, just for learning purposes. If it too much, all good, I understand.

[Hamie]

Re: Dead Samsung Plasm needs Help

Well if it was blinking once every 5-6 seconds it would indicate a sustain board failure.

You said in your initial post that your panel is glowing (or slightly light up) this shows that the y-sustain should be working.

You'll need to check vscan/vsc voltage on y-sustain to confirm.
Also check Ve voltage on the x-main

There should be test points.

[Hamie]

Re: Dead Samsung Plasm needs Help

Think the vscan test point is here.

[bwilliams60]

Re: Dead Samsung Plasm needs Help

Would you like better pics of X-SUS and Y-SUS boards? Where are the test points for these voltages. I am a novice at this so may need some help.
Are you on here for a while. I'm not used to people answering right back.

[Hamie]

Re: Dead Samsung Plasm needs Help

No just signing off,
Yes upload pictures of both boards I'll respond in the morning if no one else has pointed them out.

[bwilliams60]

Re: Dead Samsung Plasm needs Help

I measured -192.6 VDC at VSCAN and I believe I had 99 VDC on Ve on X-SUS board. Unfortunately I think shortly after, I may have smoked a tiny SMD resistor upstream from my test point. Now I have to figure out the value of it. Not good.

[bwilliams60]

Re: Dead Samsung Plasm needs Help

Replaced blown resistor. All good. Hamie, what are my next steps in this adventure. Thank you for your help so far.

[bwilliams60]

Re: Dead Samsung Plasm needs Help

Dead resistor replaced. What's next with this unit?

[Hamie]

Re: Dead Samsung Plasm needs Help

So are you still getting vsc and ve voltages that match the sticker?

[bwilliams60]

Re: Dead Samsung Plasm needs Help

Yes I am. Same voltages I posted earlier.

[bwilliams60]

Re: Dead Samsung Plasm needs Help

Can you throw out a few checks as I know you won't be on here for the weekend? Much appreciated.

[Hamie]

Re: Dead Samsung Plasm needs Help

ok, do you have perfect "permanent" voltages.
You have panel glow (this would suggest that your y-sus is good)

But you can't get test patterns.

Likelyhood your control board is faulty.

[dulipra]

Re: Dead Samsung Plasm needs Help

Hi guys, my Samsung Plasma PS51D550C1 is dead.
should be a power board problem. some resistors are blown. can anybody help me to find the parts numbers?

BN44-00444B REV1.2


FP801S
BP801S
NT801S
NT802S
QS801S
QS802S
DS803
DS804
RS814
RS816
RS815
RS817