Samsung PS51D550 no picture!

[Tolmulest]

Hello!
I have Samsung PS51D550 plasma tv.
I had it without picture and i have replaced Y sus and Y buffer boards, because they were shorted.
But i still have no screen, if i turn on the tv i see quick flash at the bottom of the screen and then VS, VA and VE starts dropping and stays at ~20v.
If i Disconnect the ribbon cable between Y-Sustain and logic board VS,VA and VE stays at right voltages.
Im really confused and i dont understand whats wrong, any ideas?

Any help would be appreciated!

[sordids999]

Re: Samsung PS51D550 no picture!

pictures of the boards may help you further to fix your problem

[Tolmulest]

Re: Samsung PS51D550 no picture!


Boards marked with Blue crosses are changed with new working ones.
Ribbon cable with red cross is buffer and y-sustain cable if its connected then VS, VA, VE will drop! If disconnected VS, VA, VE will remain normal.

If you need pictures of every board single i will make them!

And thanks for answering!

[mmartell]

Re: Samsung PS51D550 no picture!

First, are you CERTAIN the replacement boards are working boards or you were just told that ? If the boards ARE good then you could have a faulty control board. Have you checked the zsus for shorts ?

[Tolmulest]

Re: Samsung PS51D550 no picture!

Yep im pretty sure that replacment boards are working. How to i check the z sus for shorts? I checked Y-sus with multimeter between VS and ground and i got resistance so the Y sus was shorted(Measured the new board with same technique didnt get resistance). I used the same method with Z sus and didnt get resistance. Should i check something more? And buffer board had one chip shorted to ground. New one doesnt! Did like it in this video to check for shorts https://www.youtube.com/watch?v=51SZsfH60EY

[Shinju]

Re: Samsung PS51D550 no picture!

Check for small/micro cracks in the corners, I think these 550 series are known for bad glass and cracking.

Disconnect your ZSus and power on the unit and see if you get the Samsung chime on power up.

Are you getting any chime when you disconnect the y-main ribbon and power on the unit?

[mmartell]

Re: Samsung PS51D550 no picture!

Yep im pretty sure that replacment boards are working... I checked Y-sus with multimeter between VS and ground and i got resistance so the Y sus was shorted(Measured the new board with same technique didnt get resistance). I used the same method with Z sus and didnt get resistance.

This is backwards. If you get no resistance then you have a short. Where did the boards come from ?

[Tolmulest]

Re: Samsung PS51D550 no picture!

Shinju: What cracks? On the corners of the screen? If so i have checked it already and havent find anything unusual.
What do you mean by samsung chime?

mmartell: i ordered them from Trusted ebay sellers.

[capkid]

Re: Samsung PS51D550 no picture!

Like a lot of these Samsungs, I'd check the components on the Y-main and X-main heat sinks for shorts. The X-main and Y-main can kill each other if either is bad.

Samsung startup melody: http://youtu.be/ogONgEQySTc

[mmartell]

Re: Samsung PS51D550 no picture!

The melody can be disabled in the menu so cannot be counted on to chime if the PO disabled it.

[Shinju]

Re: Samsung PS51D550 no picture!

True, but I have yet to come across a Sammy that had the audible chime turned off!

[mmartell]

Re: Samsung PS51D550 no picture!

My personal sammie has it disabled but you may be right about most others.

[capkid]

Re: Samsung PS51D550 no picture!

This is a slightly different model, but the tips should be applicable to your TV: http://youtu.be/-7zWKY2Hwnc

[tom66]

Re: Samsung PS51D550 no picture!

True, but I have yet to come across a Sammy that had the audible chime turned off!

All but one of mine had it turned off... The one which had it was very useful in the diagnosis process.

[Shinju]

Re: Samsung PS51D550 no picture!

All but one of mine had it turned off... The one which had it was very useful in the diagnosis process.

I have been pretty fortunate on all the Samsung panels I have gotten only 4 of them out of 30 or more have been a total loss.

I always tell the people I sell em too or give them too to leave that chime on in case of any failure that might cause the screen to not display a picturenit helps the tech/me diagnose things a little easier.

Nothing like like calming your nerves when you hear that annoying chime sound off when you repair a sammy!

[Tolmulest]

Re: Samsung PS51D550 no picture!

No chime maybe its disabled.
Any tips how to check xmain shorts?

[tom66]

Re: Samsung PS51D550 no picture!

Check Vs and GND on X-main using 2000 ohm range, do this with power off and unplugged.

[Tolmulest]

Re: Samsung PS51D550 no picture!

No resistance between VS and ground.

[Tolmulest]

Re: Samsung PS51D550 no picture!

Also the board is removed from tv

[mmartell]

Re: Samsung PS51D550 no picture!

There you go then.