So here's one for you guys... Samsung UN55D7000

[smackcat73]

Sooooo...
I bought a Samsung UN55D7000.
It all started when the unit would be working perfectly fine and then a dark bar (about a quarter of the screen) would appear from the bottom, traveling horizontally. Shortly after, the screen would continuously start to power cycle on and off - over and over and so on. The dark bar doesn't have a definite stopping point as it travels up towards the top of the screen, it more so fades in normalcy. (See pictures) The lady I bought it from says they replaced the Power Board and the problem continued.
I checked the power board - all looked good. I bought a new main board hoping it was an issue there. I replaced it and no luck. Same problem.
I turn the TV on and now the black translucent bar is there from the start and all it will do now is power cycle on and off continuously.
I was messing with the connections on the back of the TV hoping it was a connection issue, no luck. The TV continued with its seizure-like ailments.
Randomly, after power cycling forever, the black translucent bad disappeared from the bottom and the TV stayed on and appeared like it was going to pull through. Instantly after making metal to metal contact with an HDMI cable and the main board connection for the HDMI, the unit's black bar reappeared and the fun started all over again.
I am totally baffled.
Would this be a T-Con board issue!? Or am I looking at a faulty LCD/LED panel issue (hopefully not)? Every so often (very rarely) when the unit is power cycling, the whole screen will monetarily light up with a scrambled display of nothingness of disconfigured signal. It seems to me this wouldn't be a panel issue as the problem comes and goes. But it's normally an issue 95% of the time, the other 5% it'll work normally. The unit will not power cycle unless the black translucent bar on the bottom is there. When it's not there, the TV works just fine - as it SHOULD!
ANY help will be appreciated. This thing has me stumped. It's mannerisms are totally weird and confuse the S out of me.
The first picture is of the unit when it randomly doesn't have the black translucent bar on the bottom. The second picture is when the black bar is there on the screen and when it power cycles continuously.

What a headache.
GOD bless, all - and Merry Christmas!
Adam

[kenny1070]

Re: So here's one for you guys... Samsung UN55D7000

Picture 2 appears to have operating pixels in the background - behind the shadow (bar).
Is the image behind the shadow frozen - or - in motion?

Hooking it up to a dvd or some other source you can display an actual image, and would probably help define if its in motion / frozen / ghosting.

[smackcat73]

Re: So here's one for you guys... Samsung UN55D7000

The picture behind the shadow bar is in motion. No frozen pixels, just shadowing. The pixels themselves seem to be fine, it's just a dark bar that is my problem (along with the power cycling associated with the bar).

[tom66]

Re: So here's one for you guys... Samsung UN55D7000

I suspect a bad LED strip in the panel. We have already talked on AVSForum about this.

[kenny1070]

Re: So here's one for you guys... Samsung UN55D7000

This sounds more like a backlighting problem.

If you could hook it up to an image source, that would certainly be helpful in trying to confirm imaging.

[smackcat73]

Re: So here's one for you guys... Samsung UN55D7000

OK, I will try to get an image behind the shadow sometime on Friday or Thurs. I will not be able to do so until then.

Ya, the shadow fades into normal viewing, making me [I]think[I] it's not a bad panel problem, but I don't know...

[kenny1070]

Re: So here's one for you guys... Samsung UN55D7000

I agree with Tom66 that its probably a bad Led bar.

I'm actually in the process right now of doing a replacement on a 6400.

[smackcat73]

Re: So here's one for you guys... Samsung UN55D7000

...bad LED bar... how bad is that!? Is that a fixable option for a DYI'er? Kinda a novice here with hopes to become educated. I surely don't want to bring this thing to the "Geek squad" at Best Buy.

Would a bad LED bar work normally sometimes and not work other times?

[kenny1070]

Re: So here's one for you guys... Samsung UN55D7000

That depends on how comfortable you feel in opening the panel unit - very fragile.

Not an overly hard project, but does require a lot of care and patience.


But I would certainly try to confirm this - before throwing any more parts at it.

[smackcat73]

Re: So here's one for you guys... Samsung UN55D7000

Oh OK... Ya I think I'll prob try and get it confirmed before I do anything too drastic. Already blew $100 on a (main) board I didn't need. Haha! :/

If it in fact does turn out to be the issue, where would be the recommended place to get the replacement parts I need for that?

By the way, I want to thank everybody for helping and giving their input and advice in this matter. Thank you!!

[kenny1070]

Re: So here's one for you guys... Samsung UN55D7000

Here is where I got mine -

http://www.samsungparts.com/Products...el=UN55D7000LF


There are 2 different Led Bars - 1 left and 1 right

It appears to be on Nationwide Backorder though.

Or you can just take the part # and shop around.

[tom66]

Re: So here's one for you guys... Samsung UN55D7000

Could be loose connector for that bar.

[smackcat73]

Re: So here's one for you guys... Samsung UN55D7000

Could be loose connector for that bar.

For the love of wonderful Baby Jesus, I hope that it the issue!!

Thanks for the product link Kenny.

[kenny1070]

Re: So here's one for you guys... Samsung UN55D7000

Absolutely

On the Main Power Supply check connectors CN801a (22 pin) and CN801b (18 pin). These are the Led output connectors.
Disconnect each and then reconnect - ensuring a good firm seat.
Then start voltage testing.

[Dang]

Re: So here's one for you guys... Samsung UN55D7000

If I may add, if you do take apart and want to ensure a safe removal of the screen,that's if needed, use the frame/bezel to help support the LCD when you take it out. I have done this with a Sam 756 for a back light check and worked fine, might help here.

[smackcat73]

Re: So here's one for you guys... Samsung UN55D7000

Thank you Dang for the tip!

As far as checking the possibility of the bad LED's (the TV is not backlit LED, but side lit), do you have to get access to the panel and get a physical view of them - or is there an easier way to confirm the status of the LED's without initiating full blown surgery!?

I haven't checked the connections from the power board to the LED feeds yet...

[freakaftr8]

Re: So here's one for you guys... Samsung UN55D7000

Were you implyiing that the screen wil stay normal until you make metal to metal contact with a device cable?

[smackcat73]

Re: So here's one for you guys... Samsung UN55D7000

Were you implyiing that the screen wil stay normal until you make metal to metal contact with a device cable?

Yes that happened once. Today while "trialling and erroring" with the TV, it did not do that, this time.

Today, I unplugged the LED connection that go from the power board to the panel and plugged them back in. I took out the T-Con board and switched the two ribbon cables around that go from it to the panel.
I powered the TV on and it worked normal with no power cycling issue during and entire movie. During the movie though, that shadowing dark translucent bar slowly onset onto the bottom of the display (but didn't power cycle for some reason like it normally used to).
Today, after waking up (I work nights) I turned on the TV and the black bar was at the bottom but still not as dark as it had been before I messed with the T-Con board this morning. It power cycled a few times but not immediately one after another like it used to. I had to go to work then and couldn't "play" any longer.
This TV is confusing me. Makes me wonder if it has something to do with the T-Con board now...???
Advice!? Lol!

[freakaftr8]

Re: So here's one for you guys... Samsung UN55D7000

well I definitely don't think a tcon board can cause this kind of problem does the TV has active lighting where it shuts off an array of LEDs to achieve a perfect black level? I think there's a possibility that you're getting a voltage drop in the LED strip and the input connector to the LED strips starts at the top and as the LED's go down in series to the bottom of the screen it depends on the voltage coming out of the first led to like the second one if there's a massive drop off of input voltage then you're going to start dropping out LED's as you go down the line what I would do is take the back off and monitor the voltage at the LED's and see if it starts to drop well the bottom of the screen goes dark then that would tell me that you either have a power supply problem or a balancer problem if it has active lighting.