Problems/Failure Rate by Unit Model - New vs Old?

[ScratchStart]

dirty farmer, u still got that TV? and a multimeter? and a hair dryer? I have fixed about 12 of those TV's, if you willing to take them apart they are simple to test. unless we are talking about a problem with the actual screen....

oh, and sorry for going off topic... maybe this should be moved to the "no welder required forum"

[dirtyfarmer]

Yeah, still got it . It's still opened up, laying on a table, upstairs in my barn. I paid an authorized repair shop $75 to tell me it would cost at least $450 to fix. I told them to list the boards (part #) that they wanted to replace, on my receipt for the $75 I paid them, which they did. I then went on Ebay and found the exact boards that I thought I needed. They were $75 for both. I thought:" not to bad." Got the supposedly "good" boards and swapped them out. I also found The official Samsund service/repair tech manual on-line, and according to it , the problem I had, "Sound but no picture", could be caused by these two boards as long as two other "Power supply" boards checked OK. So I assumed the repair shop had checked them and that is why they told me I needed the ones I got from Ebay. Anyway, still no picture, and now down $150. If you can fix this come and get it. I'm in Michigan, near Port Huron. It's a Samsung PN42A450P. Also, for the "Sound, but no picture" problem troubleshooting, the last thing to replace is the screen.

[ScratchStart]

wish I was close, I'd snatch it up in a hearbeat.

the most common problem with those samsungs is a simple capacitor malfunction.

the capacitors look like this


on your main power board there will be 6 or more of them.

main power board will look something like this.


you can see those things come in many sizes, but if the bottom is not perfectly flat, or they are leaking a little yellowish crud, they won't do their job(i know someone is gonna say "that is not the best way to check them". but who has the money for a capacitance tester, and who wants to desolder each of these off the board to test them?)

I have had a few samsungs, LG's, and even a sony TV apart, and every single time it is the capacitors that are causing the problem. I'm not saying it couldn't be something else, but in my experience(however limited) caps every time.

my I had to replace 6 of them, got caps at radioshack, cost me $10.

an easy test, turn the power on to the tv, find a station, and heat the capacitors up with your wifes hair dryer(yes, I said hair dryer) if the sound comes on when you heat them up, you got your problem for sure.

also samsung boards are market on the pins and connectors that go to the other boards, each little strip will be market with how much voltage it should put to that pin.

some good info here: Grants Pass TV Repairs

[dirtyfarmer]

I've seen all the stuff about capacitor failures and all of mine looked good. I'll take another closer look with a magnifier. Yes, a cap replace would have been cheaper.

[ScratchStart]

does the repair manual have an electrical diagram? that has a feed back style power supply, you may just have an optoisolator out. that would tell your power supply not to power your sound board.

I know how dang frustrating it is to pay $600+ for a tv and then have it crap the bed.

remember any little hole in the top of the caps, or anything leaking out, it could even look like the dielectric glue stuff, and that cap is not gonna perform to spec.

half a volt drop in the output to your sound board will make the feedback loop shut down.

[dirtyfarmer]

Scratch' ,I'm going to end this TV repair discussion on this thread. I'll post a new thread in "Personal Projects (no welder required)", titled "Plasma TV fix". This can continue there if you want.

[Krookz]

Hah, thats quoted from my receiver project thread. From what I understood its not that common, sure was scarey when it was happening though.