42" Samsung plasma acting strange

[ben7]

Re: 42" Samsung plasma acting strange

Noticed the TV has faint horizontal lines slowly moving up the screen.

Just replaced a bulged Capxon in the PSU today with a rubycon YXF capacitor.

Got it hooked up.

It worked first turn on.

Lines were still present
The main filter caps must be dried out.

About 45 minutes later, it doesn't detect a signal from the RCA input. Trying to change the input, it goes to cable input. Screen has that typical no signal static, and is flickering. It stops flickering after a few seconds. I can't seem to get it to switch onto HDMI input mode. WTF!

It stopped working with no hiss/smoke, I triple-checked that I put the capacitor in the right way. Could it just be the [possibly] bad PFC filter caps doing this, or is there a cracked solder joint somewhere?

Any clues?

[tom66]

Re: 42" Samsung plasma acting strange

I doubt main filter caps. These things will run those caps completely dead before you get flicker. They've got some 3000~5000uF at 200V. One Philips plasma I have right now on my floor will run for half a second with no picture... it just fades out slowly then dies.

Faint lines suggest HF interference -- check all screws secured ground wise... Also it is an older generation, MAY be typical. I have seen a similar effect on the 65" Samsung plasma mounted in the foyer of our Electronics school at uni.

[ben7]

Re: 42" Samsung plasma acting strange

I doubt main filter caps.

Faint lines suggest HF interference -- check all screws secured ground wise... Also it is an older generation, MAY be typical. I have seen a similar effect on the 65" Samsung plasma mounted in the foyer of our Electronics school at uni.

I checked to make sure all screws were tight earlier, before I put the TV back together. Everything was perfect. I also checked the connectors, they were seemingly solid too.

We never had the faint lines, until a few months ago. They are only visible on dark colors, like dark gray, dark blue, dark green, etc...

[tom66]

Re: 42" Samsung plasma acting strange

Pics?

Could be bad voltage regulator, or other bad caps elsewhere.

[ben7]

Re: 42" Samsung plasma acting strange

Pics?

Could be bad voltage regulator, or other bad caps elsewhere.

I will have to wait on the pics ... I took some earlier, but they were not top-downs, just random images. The only place to fix something large like this is, at the moment, the kitchen table :P

AH, hm. I was mistaken, I replaced the cap with a rubycon YK. No wonder! I bet that thing has bulged now, it was in a buck circuit in the PSU. The other capacitor (which I had replaced about 2 years ago) is the YXF.

I noted all the cap values earlier, will get replacements soon when I order a list of other parts...

2x 220u 450v CapXon HP
1x 680u 250v CapXon HP
1x 22u 450v Samyoung KMX
6x 47u 50v CapXon KM
2x 1000u 25v CapXon GL (currently 1000u rubycon YXF, and 1000u rubycon YK(not suitable for app.?!))
2x 470u 35v CapXon GL
5x 10u 50v CapXon GL
2x 22u 50v CapXon KM
2x 220u 25v CapXon KM
1x 100u 50v CapXon KM
1x 680u 100v CapXon GF
4x 1000u 35v CapXon GF

[ben7]

Re: 42" Samsung plasma acting strange

HMM, interesting!

It seems that there is a bad solder joint inside somewhere - I tried turning the TV on today and it worked. Then after about 15min, it went to the 'no signal' business again!

[tom66]

Re: 42" Samsung plasma acting strange

Bad main board -- BGA problems?

[ben7]

Re: 42" Samsung plasma acting strange

Bad main board -- BGA problems?

IDK, hopefully not! (I don't have a hot-air station, though I do know someone who might have one at his workplace)

I will have to try plugging in the input in the back of the TV, not on the side.

I do remember unplugging (and plugging back in) the cable that connects the side-input board to the main board. Perhaps there is a bad solder joint there...

Or else a voltage regulator, or capacitor has gotten far worse. The new capacitor in the PSU didn't fix the problem.

[ben7]

Re: 42" Samsung plasma acting strange

Got it taken down today.

Opened up, and played video through it, on the same input (from side of TV).

The Rubycon capacitor I put in there before was fine.

Waited 1/2 hour, and it didn't do anything strange!

Tapped on all the chips and stuff with a de-barked and dried branch from a tree outside, nothing strange!

ahhhhhhhh

[ben7]

Re: 42" Samsung plasma acting strange

No thoughts?

I tested it again today for an hour, with the back on. No issues!

I am thinking either it was/is a cold solder joint, or the verizon DVR box...
For testing I used a VCR/DVD player

[ben7]

Re: 42" Samsung plasma acting strange

Umm ... wtf

Put it back on the wall, its been good for 5+ hours now.

I guess it was a cable that I re-seated...