Samsung UN55D6450 turns itself off and on endlessly, no blinks

[tibimakai]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

It's not a big deal to open the panel. I wouldn't even open it up completely, just lift it a bit and then turn it on, to see what is going on with the LEDs.

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Before I open this panel, let me throw a few things out there that makes me think maybe it's the PS board.
I can't turn it off, once I plug it in, it just cycles on and off endlessly. Also, everytime it does so, the relay clicks. After you pull the plug the relay keeps clicking, but at a progressively slower pace, until it "runs out of steam". If this is suspect, I can post a video.
Still think it's an LED strip? Please say it's just some caps or something.
Thanks,
Alex

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Unfortunately, there are two plugs, but each has a different number of pins/prongs.

[tom66]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Just as a test, is it perhaps possible to swap the output of each? Are there four separate connectors for each output to the panel or just one?

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

So I have to go into the panel, huh? That looks awful. It seems to be held together with tape in such a way that it'll be hard to get back together and fragile as hell once it's apart.

[tom66]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

The one on the right makes me think you have an open circuit LED string; I'll bet that's causing your problem. The number of these LED sets with failed LED strings is crazy. So many going bad because one LED goes bad.

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Any ideas, guys? I don't have to be in the field again til Tuesday, so I can put some time into this.

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

OK, I have zero idea what I'm doing, but I played around testing some points on the PSU. I set my DMM on 1000VDC, put the black prong on a chassis ground, and touched the red to a number of places. All directions are facing the back of the TV.

All 4 of the yellow transformers (L-R L9451, L9351, L9251, L9151) put out roughly the same numbers between cycling on and off (125ishV to 90ishV) on both legs. The long caps directly above each transformer say something when tested one the left leg of each. The three on the right (L-R C9355, C9255, C9155) put out the same numbers 160ishV to 110ishV, while the one on the left (C9455) puts out 260ishV to 130ishV. Above that, there are three white boxes (capacitors? They're marked "C") which mirror the issue when tested on the left leg of each. The three on the right (L-R C9359, C9259, C9159) run about 160ishV to 110ishV while the one on the left (C9459) runs about 270ishV to 130ishV.



Does this point towards anything?

Thanks,
Alex

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Tried it, nothing changed. Thanks though!

[tibimakai]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

This is just an idea, may not be your issue.
I would disconnect the ribbons going to the panel from the T-con, to see if it stays on.
I have a UN46D6420 which seems like it has a bad panel. With one ribbon connected, I have half screen working great, with both connected, I have only backlight.
I have repaired a Sony which did almost as yours, but stayed on almost 20 sec. and it ended up being the LED driver board which was a separate board. On yours is most likely is build in in the power supply board. Maybe those four yellow transformers.

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

After reading up on Samsung cap and PSU failure, this error sounds like it could be in the PSU. Rather than drop a 100 bucks on this board though and before I crack open the panel itself, I'd love to see if I could try and evaluate this on the component level. Unfortunately, this puts me in way over my head. I've got the schematic, but am fairly lost as to how to read or interpret it to any degree that will help me test anything out.

Do any of you delightful gents want to point out some pins or something I can test to determine if the LEDs have failed or if it's on the board somewhere?

Also, no caps appear bulged, all PSU fuses test fine, and the pico fuse on the TCON is ok as well.

Thanks all,
Alex

[RJARRRPCGP]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

It may be a primary issue.

[freakaftr8]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

You cannot ohm an led strip. I'm learning about this more and more. The led tv incorporates a "balancer" to judge if the led strips are working optimal or not. What you need.ro do is get the service manual and find what voltages are on the balancer pins and led controller ic but im betting in you having some internal led error.

[tom66]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Any way you can get a full lit screen, maybe full white?

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Yeah, the bottom 1/4 or so of the screen is dark. It's *really* hard to tell in this video, but here it is:
http://s294.photobucket.com/user/wit...07841.mp4.html
Is there any way to test the pins to see if its actually the LED before I open up the panel?
Thanks,
Alex

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Found a main for 80, disappointingly didn't do the trick. I looked more closely at the screen as it turned on and off, and the bottom edge LED lights may not be turning on. Is there a way to test this better?

Next time I go home, I'll take video in a dark room.

[capkid]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

I also like to get main boards from Tristate Module, since they offer a 6-month warranty. I almost had to return a main board before I figured out that an obscure firmware update was necessary along with the main board replacement, and Tristate didn't hesitate to take back the board when I called them. So, I'd keep an eye out for an available board on their site.

[tom66]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

You can also set a notifier up with ShopJimmy.

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Ok, I'm putting this on the backburner until I get a notification from ebay that one of these boards has become available. If it works, I'll update so there is a thread out there in case someone else encounters the same problem. If it doesn't, I'll go the TCON route.

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Yoicks, I can't find replacement main board for this anywhere except TVserviceparts, where they want 175. Anyone have any leads? It's p/n BN94-04359V. Shopjimmy lists these as substitute parts:
BN94-04357J
BN94-04359U
BN94-05038U
BN94-04359W
BN94-05038N
BN94-05038R
BN94-05038Y