Samsung PS51F5500 revival

[chopduel]

Hi all,

I've had my Samsung PS51F5500 plasma tv for a decade or so. I bought it when it was one of the last units on sale, when plasmas were almost completely gone from the market, and it's been great and I was very happy with it.
About a couple of years ago it started sporadically turning off and back on again, every once in a while. I assumed it's due to voltage irregularities in the mains or something.
then, about a year ago it sometimes would turn off, the led would blink for a while, and I'd give it a rest, after which it would work again as usual.
finally, about 2 months ago it just died and wouldn't turn on.
I've ordered a replacement power board and put it instead of the old one. Now I'm getting the red standby LED when it's off, but when I try to turn it on, it just blinks 5 times and doesn't turn on.
I assume (from watching a couple of YouTube videos) that it's probably the main board that's dead or damaged.

The only place where I've found one available for purchase is "tv parts today" which I see has not so good reviews, and it's the last one in stock according to their website.

Question is what would be the best move on my part? Risk around $65 and order the board, or just save my effort and cash and go get a new tv?

I'm not even sure it's the main board that needs replacement in this situation.

thanks

[nomoresonys]

Maybe start with easy stuff, I suppose you already checked for bulging electrolytic capacitors, Have a good look at the solder joints on underside of original powerboard, reflow any that look suspicious, look closely at the solder joints of transformers and anything on a heatsink, they can crack over time and need reflowed. Put your original powerboard back in, make sure ALL the screws are in place and snug not loose and make sure all the other screws in the other boards are also snug but don't over-tighten don't want to crack a board, they run hot and screws can/do loosen up and will short things out if they get too loose, lock washers can remedy the problem. Try the tv if no change, heat the electrolytic capacitors on powerboard with a hairdryer for a couple minutes then try the tv, see if it comes on or anything changes, don't wait til the board cools down, try it while it's still hot, if no change, try the same heating of the electrolytics on the other boards one board at a time, examples of bad solder joints there: https://www.google.com/search?client=firefox-b-1-e&sca_esv=597380833&q=bad+solder+joints&tbm=isch&s ource=lnms&sa=X&ved=2ahUKEwi5o4HdmNSDAxXgm4kEHf-QBwMQ0pQJegQIDBAB&biw=1238&bih=544&dpr=1.09

[chopduel]

Thanks for your reply.
Yeah, I have looked at the capacitors and they look fine from what I remember.
What is the purpose of trying this with the old power board? Do you suspect that the replacement board may be faulty?

[nomoresonys]

Kind of hard to tell but I think it may be easier to troubleshoot the original powerboard, remember a cap doesn't have to look bad to be bad.

[nomoresonys]

Did you do all the steps in my post?

[chopduel]

I've inspected the board to the best of my ability
capacitors look flat, no bulges
I have found one slightly cracked solder joint on the underside, and a few others that look peculiar (like chicken feet) but maybe that's how they're supposed to be. I've attached the photos here for you to see.

[nomoresonys]

Dave doing a demonstration, he knows his shit, he's forgotten more than most of us will ever know: https://www.youtube.com/watch?v=TXGxE9Fxhlw

[nomoresonys]

I've inspected the board to the best of my ability
capacitors look flat, no bulges
I have found one slightly cracked solder joint on the underside, and a few others that look peculiar (like chicken feet) but maybe that's how they're supposed to be. I've attached the photos here for you to see.

If it's cracked reflow it add some solder if needed, posted the bad joint images in the other post.

[nomoresonys]

To do things as efficiently as possible, people need to do these first simple tests as instructed and give results of each test, time is precious, there's no way I can help without this simple procedure, test one results were this, test two results were that etc.