PL51D550C1G Plasma Samsung - No picture, but sound is ok

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

I checked some voltages on my TV when it is on pattern test and they aren't normal: VS ~450V; VA ~125V; Ve ~180V;
They should be: VS 205V; Va 58V; VE 80V;

This is not normal, right?

[tom66]

You are probably using AC mode on your meter - measure them on DC.

Understood. But it could be the cause of the TV turning off by itself after a few seconds?

Out of interest does it do this on the test pattern?
Control board might be detecting a fault or sending a signal to the main board to shut down PSU.

I'm just thinking... what a bad lucky I have, because I just changed the Y-main board 2 weeks ago. My TV was working perfectly, then the control board fails? This supost control board fail could be related with the previous fail (Y-main board fail)?

I wouldn't rule out the possibility but most likely it's just a case of bad luck and poor Samsung build quality.

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

You are probably using AC mode on your meter - measure them on DC.



Out of interest does it do this on the test pattern?
Control board might be detecting a fault or sending a signal to the main board to shut down PSU.



I wouldn't rule out the possibility but most likely it's just a case of bad luck and poor Samsung build quality.

Lol, I'm a retard! I was really using AC mode. I'm so angry about this that I didn't even notice.

No, the TV doesn't turn off by itself when is in pattern test mode.

I did try unplug and plug all ribbon cables but it doesn't work. I think it is probably logic board like you said

Unbeliveable!

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Hello again. I bought a working logic board but it doesn't fix the problem, now I'm suspecting it could be some ribbon cable.
There is some easy way to test the ribbon cables? There is 5 ribbon cables.

[tom66]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

You can check them using a ohm-meter for continuity, but most likely they are OK unless torn or damaged.

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

You can check them using a ohm-meter for continuity, but most likely they are OK unless torn or damaged.

I did this with both ribbon cables that connect the logic board with X-main and Y-main boards, they are OK.



I did a few tests too. I disconnected the 3 ribbon cables that connects the logic board with that board in the bottom of the set (I think it is E and F Buffer) and the image on the panel is like this: .
It could be E&F buffer the problem?

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

When all the ribbon cables are connected, the picture on the right part of the panel is a little bit distorted but when I disconnect the 3rd ribbon cable, the right part of the picture on the panel is perfect!



So, the problem could be the E&F buffer boards?

[bikerbuddy]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Find out if your local TV repair shop can sell u a ribbon cable for the suspected buffer board and see if that will improve the picture quality or if the Buffer is really bad .I have had some experience with bad ribbon cable before in the past
good luck

[tom66]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

That is not good. I hope your panel is not shorted.
Did you EVER plug in any cable to the bottom buffer while power was connected or shortly afterwards?
You should check the ribbon for tears.
IIRC, E/F boards cannot be replaced - bonded to the panel.

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Find out if your local TV repair shop can sell u a ribbon cable for the suspected buffer board and see if that will improve the picture quality or if the Buffer is really bad .I have had some experience with bad ribbon cable before in the past
good luck

I will try it, but now I don't think this is the problem. I suspect it is bad panel because when I disconnect the 3 ribbon cables that connects the logic board to E&F buffer boards the vertical coloured lines are still there. I think that shouldn't have any picture on screen, right?

That is not good. I hope your panel is not shorted.
Did you EVER plug in any cable to the bottom buffer while power was connected or shortly afterwards?
You should check the ribbon for tears.
IIRC, E/F boards cannot be replaced - bonded to the panel.

No, I always turn off the TV when plug or unplug something.

[steviewonder]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Oh dear...looks like the classic chip on film (COF) has had it..

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Oh dear...looks like the classic chip on film (COF) has had it..

So, I should say good bye to my TV?

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Here is a picture when all the 3 ribbon cables are connected with E and F buffers:

And here is a picture when I disconnect the ribbon cable from the F buffer:

Also, when I disconnect the ribbon cable and the power cable from the F buffer board, there is no picture on the left side of panel but on the right side the picture is perfect.
So, I'm guessing here but I think the problem is some IC on the ribbon cable, like steviewonder mentioned. This is not repaireable, right?

[tom66]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Yes, it looks like a panel failure sadly.
I am really confused though, that looks like more than one IC has failed.
This can only happen due to overheating of that part of the panel, or a power transient from making a connection while power is still active.
Overheating - if the heatsink for the X-drivers was removed, panel will fail in a couple minutes operation.

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Yes, it looks like a panel failure sadly.
I am really confused though, that looks like more than one IC has failed.
This can only happen due to overheating of that part of the panel, or a power transient from making a connection while power is still active.
Overheating - if the heatsink for the X-drivers was removed, panel will fail in a couple minutes operation.

I never removed anything, I just changed the Y-main due to the previous failure mentioned in this topic. Then, 2 weeks after I replace the Y-main board, this happened
Plasma TVs never again (although I really liked this one before all these problems occurred)!

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

I took my TV to a local tech, he said both X and Y main board are shorted. Is it really possible?

[tom66]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

If you have a picture (with lines or not), no. They cannot be shorted.

Plasma TVs are generally more reliable and repairable than LCDs (due to the high failure rate of the LED backlights and LCD panels), but sometimes diagnosing and fixing them can be difficult.

I really liked the picture quality from the PS51D450 I fixed a while back.

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

If you have a picture (with lines or not), no. They cannot be shorted.

Plasma TVs are generally more reliable and repairable than LCDs (due to the high failure rate of the LED backlights and LCD panels), but sometimes diagnosing and fixing them can be difficult.

I really liked the picture quality from the PS51D450 I fixed a while back.

Sure, I love the picture from this TV! I think it is much better than my LED TV! That is why I didn't give it up after months of trying to fix it. But I think it is a dead end now

[rogerazambuja]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

Yes, it looks like a panel failure sadly.
I am really confused though, that looks like more than one IC has failed.
This can only happen due to overheating of that part of the panel, or a power transient from making a connection while power is still active.
Overheating - if the heatsink for the X-drivers was removed, panel will fail in a couple minutes operation.

Sorry for bumping this thread, but after months I just checked out my TV again. I realize that when I was trying to solve the first problem (Y-main board failure) I probably removed the heatsink for E-F buffer, and it is lacking 3 "thermal adhesives" for the 3 ICs (COF) under the coloured lines on screen, so the ICs was not touching the heatsink. I didn't notice this, so probably when I put the new Y-main board (first problem) and start to use the TV again it may damaged the IC's due to overheating (it worked for 20 days)
So, to fix this it is probably necessary to change the whole panel. Not worth it.

[tom66]

Re: PL51D550C1G Plasma Samsung - No picture, but sound is ok

That is a shame. I am very surprised it worked for 20 days. We have had users on here who have omitted heatsink parts and found the set to last only 10-15 minutes before failure. Ah well, it is a lesson for the rest of us, unfortunately your TV had to die for the cause

Do sell the parts from the TV--it could be at least an organ donor!