My RCA tv crapped out =( Advice?

[sidneyaks]

Ok, so my RCA tv took a big dump all over my day. It's starting dropping the video entirely at random intervals - I can be watching TV and all of the sudden the screen shuts off. I can hear audio, but no video. So I took it apart and went over both boards and found a few oddities on the power supply board. Above a 100 uf 450v elite brand cap there is a dark brown scorch mark on the board, and on the other side there is a black scorch mark. Finally, on the piece of plastic the board sits on, it looks like that area has been melted. This cap is obviously suspect, but since it's burned the board, is it still usable?

Also, some of the solder joints look a bit funny, where they normally follow up the wire smoothly, some of them have little pits and divots in them, are these bad solder joints? Is fixing them as simple as just reheating them and making sure they are completely and properly heated, or do I have to remove the old solder and redo them?

I've fixed a few TV's I've got off of craigslist that were just obviously bulging caps, but I've never found one with cold joints or burned boards, so I'm a little unsure. Any opinions would be great here, thank you.

[burntfingers]

Re: My RCA tv crapped out =( Advice?

Random intervals could mean dry joints.
Wiggle the boards gently, to see.
If the set went completely off, while the main switch is on, you should be very careful with high voltage caps in the power supply, the big smoothing one quite violent when discharging through a multimeter or solder or your hands!
Always use a 100W lamp or some other standard procedure to discharge them BEFORE handling anything in the primary side of the power supply.

[sidneyaks]

Re: My RCA tv crapped out =( Advice?

I looked up dry joints on google, and these solder joints look exactly like that! There are a bajillion of them to be fixed, but hey at least it's fixable.

I always unplug any device I'm working on, let it set for at least 24 hours, and then try and turn it on before I work on it. Never heard of the bulb trick, but most of my experience has been of the "screw around with basic theory until it actually works" variety. Either way, it wouldn't be a bad idea to replace that capacitor anyway, right? And I s'pose I should take the mainboard out and check it too.

[burntfingers]

Re: My RCA tv crapped out =( Advice?

I looked up dry joints on google, and these solder joints look exactly like that! There are a bajillion of them to be fixed, but hey at least it's fixable.

I always unplug any device I'm working on, let it set for at least 24 hours, and then try and turn it on before I work on it. Never heard of the bulb trick, but most of my experience has been of the "screw around with basic theory until it actually works" variety. Either way, it wouldn't be a bad idea to replace that capacitor anyway, right? And I s'pose I should take the mainboard out and check it too.

lol
I know there are other terms, but I learned "dry joints" 40 years ago, and that's what I understand by a bad soldering point.

http://www.pcuser.com.au/pcuser/hs2....256F2500358412

Many, many faults are the result of dry joints, some being terribly nasty.

The lamp [incandescent light bulb] technique is efficient, because the cap is discharged thought the filament, which lights up for the discharging period.
I use it all the time.
Solder a burnt fuse to its terminals [a bayonet type] and touch the cap's points with it.

[sidneyaks]

Re: My RCA tv crapped out =( Advice?

Ok, I went through and fixed all the weird looking joints and turned it on, and in about 2-3 minutes it went back off again, but I did notice this time that near where the power supply board is, I can hear a really high pitched squeal from behind the tv. Also, it seems to be happening a lot quicker than when it started.

[Krankshaft]

Re: My RCA tv crapped out =( Advice?

What kind of TV are we talking about here CRT, LCD, Plasma?

A model number and pics of the boards would be helpful.

[sidneyaks]

Re: My RCA tv crapped out =( Advice?

It's an RCA l32wd22. Here are pictures of the power board, upon inspection of the main-board it looks fine. I circled the burned areas on the front and back. I figure while I replace those two elite caps, I'll get the ones on the hot side, to avoid the problem mentioned in the other thread concerning this tv.

[Village Electronics]

Re: My RCA tv crapped out =( Advice?

It's an RCA l32wd22. Here are pictures of the power board, upon inspection of the main-board it looks fine. I circled the burned areas on the front and back. I figure while I replace those two elite caps, I'll get the ones on the hot side, to avoid the problem mentioned in the other thread concerning this tv.

What is the arrow pointing to?

[sidneyaks]

Re: My RCA tv crapped out =( Advice?

It's a resister that they didn't pull the lead all the way through on. It's sticking up at about a 45 degree angle and they covered it with heatshrink tubing. There are a few of them on the board.

I went ahead and decided to get all the caps on the board replaced, so I picked them up from the local electronics supplier. The only thing is there are two 47uf 50v caps, and he didn't have those, but he said 47uf 150v caps would work - Can I go with this, or should I acquire the proper rated caps?

[tom66]

Re: My RCA tv crapped out =( Advice?

It's a resister that they didn't pull the lead all the way through on. It's sticking up at about a 45 degree angle and they covered it with heatshrink tubing. There are a few of them on the board.

I went ahead and decided to get all the caps on the board replaced, so I picked them up from the local electronics supplier. The only thing is there are two 47uf 50v caps, and he didn't have those, but he said 47uf 150v caps would work - Can I go with this, or should I acquire the proper rated caps?

47u 150V will work, but will physically be bigger.

Make sure the caps are low ESR and ideally a good brand e.g. Panasonic, Rubycon, NCC/UCC, Nichicon...

That big primary side 400V 150u cap looks like it is bulging from this angle. Given that it is near heat, not unlikely. And it would explain the symptoms in question.

Quick test - how well does the TV work when the LCD brightness is turned down? If it works well at minimum brightness, it's either a problem with the inverter, CCFLs, or bad caps (possibly the big primary side cap.) I'm more inclined to say it's the cap.

[Zeidoo]

Re: My RCA tv crapped out =( Advice?

Hi sidneyaks,

Did you ever fix your problem? I got the exact same one. I replaced the big 100uF 450V capacitors but same symptoms, the TV shuts down after a maximum of 3 minutes.

My board has all the burn marks yours has.

Thanks!