Samsung LN40A650A1F Vertical Lines (On Input)

[Kiyoshi5891]

Hey, long time lurker here and frequent visitor of badcaps for excellent information. However this time i am stumped and was wondering if anyone would be able to assist with any sort of information as to the issue.

The tv at hand is a samsung ln40a650 model which was working fine but began showing signs of issues two days ago with the whole screen showing vertical green bars and making a loud buzzing sound from the speakers. I disconnected the power to the speakers via the logic board to see if the sound was from them, and indeed it was. Once disconnected the green bars appeared but no loud buzzing sound. If the tv is cycled on/off many times the picture will appear for a second but then freeze (with a fuzzy look) and then the tv will restart itself over and over.

I already replaced all the bigger capacitors for testing purposes but this did not solve the issue. Another strange thing to note and of importance is that if no devices are plugged in (cable via hdmi, pc on vga, or antenna) the tv work just fine. No image distortion, no green bars, full menu works, the "no devices" just shows beautifully. Also, if I attach a usb stick and go to the wiselink (media player) all graphics and menus work fine, pictures display without issue, and even playing music for hours (testing if it would shut off or fail) works fine.
Sadly wiselink doesn't have a video Player, not that I am aware of at least. So i am Led to believe that video playback is causing the tv to crash.

Anyone out there know what bizarre cause this is? Any ideas where to look at if say on the tcon or logic board? Thanks for your time and help solving this puzzle.

[Kiyoshi5891]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

Unfortunately I cannot get the green bars to reappear, I am now just getting the tv turning on, then showing "hdmi 2" then when it tries to load the screen it turns off and restarts then repeats the same issue. Attached are pictures of the boards for reference. (These were taken pre-cap change, but perhaps someone with a sharper eye could spot an initial bad capacitor)

[Kiyoshi5891]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

Minor update, switched back all caps back to original to test, and can once again get music and photos to work 100% of the time via usb. However once an input such as antenna or hdmi is plugged in and is switched to that source the tv reboots and just does the turn on / turn off cycle with flashing red led (4/5 times). However once disconnected from the tv, the tv starts right back up just saying no source.

Still don't get how it can function wonderfully playing audio, as the seek timer and bar is in motion so it cant be an entire video issue. Perhaps its the logic boards inputs? Has anyone come across an issue where only an input sticks the tv into a reboot loop?

Update:
Added a look at the logic board and a zoom of the surface capacitors; never came across a problem with this before but I am noticing minor "X" portroding from the tops of them (not broken though) while other similar look caps on the board are flat and dont have these raised marks.

[Kiyoshi5891]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

Another Quick Update with board and tv working via usb pictures. Would have added it to the last post, but the 90 minute edit window is up. As can be seen on the underside, looks like some weird goo on the top back of the board, Cleaned it off and still nothing.

[tibimakai]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

I had a 46" with corrupted image and screeching sound(very loud, can't take it for to long) and it ended up to be a bad main board.
First of all, I would replace, all the electrolytic capacitors with Panasonic FC or FM series capacitors from Digikey. Just to exclude the capacitor and it's not expensive, maybe around $12-15 shipped.

[DemonBG]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

i would say with 90% certainty that this is a main board problem... If it was panel / Tcon then it wouldn't matter what input you select or what was / wasn't plugged in.

Try pressing down on the main IC's on the main board to see if it makes any difference and failing that see if you can do a factory reset (Info-menu-mute-power, then options and factory reset) to rule out any software issues?


Good luck,
Demon

[Kiyoshi5891]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

Thanks so much for the replies. Tibi, I may order the panasonics if this last question doesnt work, so we'll see if those do anything.

But Demon, I gave probing around a try and found that 3/4 the time if i press and hold with a bit of force on "3002KW SK 832 47 0c" (picture attached) the image comes right up but crashes shortly after releasing it (I do not have the steadiest hands so it drops sometimes while holding). Would you think re-soldering this piece would help, or if a new one would be better off? Thanks so much! Cant believe it may just be a little transistor(?)

Update: yup, definitely something on the main board. If i press with enough force on the composite inputs (right below that transistor 3002KW) the video comes on until I let loose then it freezes (pic attached)

[DemonBG]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

Ok it sounds as though you may have a cold solder joint somewhere near the composite ports.
It can be tricky finding the true culprit and depending on your soldering skill it may be worth just buying a new board (especially if they are cheap).

Personally I would pick up a soldering iron / heat gun and start reflowing solder!


Good luck,
Demon

[tom66]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

My guess would be a problem with the soldering on that main processor BGA. The one under the heatsink. Or possibly the RAM next to it. Same failure as Xbox 360 / PS3 lights-of-death = cold/cracked solder joints on processor.

[Kiyoshi5891]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

Thanks for all the contributions. I tried re-flowing some chips nearby the problem area, but it still shows the same issues. An interesting troubleshoot run through produced the following:


HDMI 1 - displays image freaking out (video attached in zip)
HDMI 2-4 (#4 located on side) - Reset Loop
Composite 1 - Doesn't pick up anything, doesn't work
Composite 2 - Works temporarily before freezing*
AV (RGB on side) - Works temporarily before freezing*
VGA - works 100%
USB - works 100%
TV Tuner - Reset Loop when signal, works when only audio (not enough signal for video), and works fine with no antenna attached

* = See Attachments; Video works on game system loading screens [gamecube (av) xbox (composite)] however the second a game is started the screen forms the vertical lines (attached would be the tvs attempt at loading Mario Kart).

A new main board would probably fix the problem, but as an engineer I enjoy fixing things, so at this point its more of just a fun challenge to learn. I'd love to reflow it with a heatgun, but unfortunately all I have is a hair-dryer... And that never worked too long with any RROD repairs. If anyone has ever run across such oddity feel free to share, if not, I'll keep this thread updated over time in case someone else hits this issue someday.

[dkneyle]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

I too have a somewhat (but not identical) issue with a Sammy LA46F71B, which I've pretty much determined to be the mainboard. It was intermit. but has now gone permanently into the fail state. I tried with a heat gun to see if I could get any re-flow happening, but no change. As a last resort I was considering placing in a domestic oven as I've done with some PC hardware to get it going again (I figure nothing to loose). However the board has quite a few plastic connectors. Are they thermoplastic or thermosetting type plastic do you reckon? If they are thermosetting they probabaly could go through an oven OK.

[tom66]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

The connectors well be rated for about 250 C no problem. They go through a reflow oven during assembly.

[xredhawk]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

i may have mainboard for this tv , plus power supply ,from tv with cracked screen

[PatchDog]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

i may have mainboard for this tv , plus power supply ,from tv with cracked screen

What's the part number on your main board. Mine is having the exact same problem and I'm interested if you still have it. PM me the details.

[Mike95inNJ]

Re: Samsung LN40A650A1F Vertical Lines (On Input)

My guess would be a problem with the soldering on that main processor BGA. The one under the heatsink. Or possibly the RAM next to it. Same failure as Xbox 360 / PS3 lights-of-death = cold/cracked solder joints on processor.

I know this thread is old, but I followed Tom66's advice with heating the mainboard processor and a few other areas on the board with a heat gun on low and it fixed my problem of the rebooting when plugged into a input. Thank you very much.