Samsung plasma PN50C550G1F/ Sound, no picture

[Agent24]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Blown fuse means no power will get to the board, so yes, it won't work...

But fuses don't usually blow for no reason, possibly you have a short on the board somewhere you need to find and fix first.

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Thank you Agent 24 for the info. I think the fuse is first in line of the circuit, so my problem probably lies within the power supply. I have no schematic to confirm this, so I'll just leave it alone.

[tom66]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Gents, sorry for the delay with the pics, they are at http://rccrasher65.imgur.com Tom would this blown fuse cause the logic board to fail like it did? I ordered some off of ebay to try.$3.00. would this blown fuse protect the rest of the board or is it shot. I got a replacement coming anyway just in case I need it. I wanted to try a component level repair, instead of being a board swapper. thanks again for all the help guy's.

Sometimes the fuse can blow for non-obvious reasons -- just random chance due to inrush current or thermal cycles.

So sometimes replacing the fuse can fix the issue and thatr fuse may be fine for 20+ years no problem. But other times, there can be a fault on the board, or another connected board, causing that fuse to blow.

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Tom,Thanks for the info. I,m going to try and replace that fuse and see what happens,what can I loose $3.00 for 5 fuses, worth a try for me. Everything I ordered should be here on friday, going to de solder fuse from board this evening. thanks again for all the help.

[tom66]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

To remove the fuse, flood the area with solder, heat the solder, and the fuse will slide right off. Clean area with solder wick. Putting the new fuse on requires a steady hand, solder one side of fuse, allow to cool, then solder other side. Flux helps, but I usually have no problem without it.

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Thanks Tom, removed fuse with no problem, just waiting for replacements.

[Agent24]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Maybe in the meantime you could check for a short between the fuse pads and ground?

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Agent 24, can you explain how to do that. what setting on MM. complete details on how to. Thanks Relatively new to electronics.

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Well, I received my new main logic board today. I installed it to give it a try, and I got my picture back, With a big surprise! a whole bunch of black and white lines going from left to right the entire screen. You can view pic's at http;//rccrasher65.imgur.com Not exactly what I was expecting. Well give me the bad news, BAD PANEL or buffer issue. All voltages are to Panel label except XE on X main board, it reads 74V should be 89V, all other voltages are correct to panel label. I'm going to pull the buffer board and test for bad IC's, there are 12 on this one single board.

[tom66]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Hmm, it is unlikely to be a bad panel if it is your brother's and it was working OK before it died.

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Tom, He told me the picture just quit one day, and sound was present. when I started, that was the problem. Tv was stored in a game room for about 6 months before I got it. Tv was also mounted on a wall, so no base. What do you think? What to check next? The main board I purchased seems to be working well. It has the first green led flashing every second. Normal operation from what I'm told. the only voltage that is not correct is VE on the x-main. It seems low at 74V, should be 89V. Would that be the cause of the lines across the panel.Thanks for your help.

[tom66]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

I will look at your pictures at home. My workplace blocks imgur.
A low Ve will cause a pink tint to image, or pixels that get stuck and don't fire properly (dead pixel effect)

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Thanks Tom, I will check voltages again.

[tom66]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Hmm, have you at any point unplugged the Y-buffer board?

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Tom , yes I have several times, but they were very easy to take off. the connector just pops off the board. I was extremely careful when doing this, no damage to ribbon cable. Very cheesy set up If you ask me, for what my brother paid for this set in 2010.

[tom66]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Make sure that the Y-buffer connectors are fully seated. That's a textbook symptom of what happens when they aren't. They can be a right pain to get right, especially if they are the latching type.

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Tom I think you are absolutely right. They were pretty hard to get off when I first removed them, now they are extremely easy to remove, only problem I see is that there is no support under the board, so when you try to push the connector down, the board flex'es to much. the board is elevated on posts with 4 screws and nothing under where the connector is, just space, another foolish move by myself, for touching something that need not be touched! Nube Move! Once again! Thanks Tom. I'll try to re seat connectors.

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

Well I have re seated the connectors several times over with the same fault. They press on with guide pins on the ends, they can only go on one way. impossible to put on wrong. seated all the way on, with the same result. the only ribbon showing no problem is the very last one on the bottom. the top 5 ribbon connections still show lines running across the screen from left to right. Could this be the y buffer board causing this fault or should I start stripping this set for parts. I tryied this several times, with the same result, lines.

[rccrasher65]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

What to try next or part out! I've tried to re seat connectors several times, with no luck!

[tom66]

Re: Samsung plasma PN50C550G1F/ Sound, no picture

It's an odd one.
I would check the ribbon connectors carefully for damage, inspect them for tears, etc.
Possibly the Y-buffer is bad, but I have never seen this symptom before.
The only thing left is panel, but if your brother said it was OK... it should be fine...