Lg 50ln5100-ub

[Fisher77]

Ok I have a LG 50LN5100-UB that a friend of mine asked me to look at. Belongs to the Shallowater ISD baseball program. It powers on no problem. What is has is a flickering screen so to speak. About the bottom 1/3rd goes burry then normal, then blurry again. It has some lines on the screen when it goes blurry. I appreciate any help.

I have posted pics:

[Fisher77]

Re: Lg 50ln5100-ub

Ok I was probing the test points on T-CON board, and found the voltage going from 28.8V and dropping to -4.9V on the 2 test point marked in the pic. I tried testing the Main board connector, but trying to get the DMM probe on all those tiny connections seems impossible. I am afraid I am going to short something out. I could just order both boards, but I am trying to keep the cost down. I have a budget of $70 to fix this TV for the baseball team, and just the main board on shop jimmy is $60. A new TV is not in their budget.

[Fisher77]

Re: Lg 50ln5100-ub

Anybody have a suggestion, point out a place to start, anything?

[budm]

Re: Lg 50ln5100-ub

If you flex the panel, does the problem change? It sounds like panel problem to me.

[Fisher77]

Re: Lg 50ln5100-ub

If you flex the panel, does the problem change? It sounds like panel problem to me.

I flexed the panel this moring in all different directions, and the problem stayed the same. I took a heat gun and heated around the edges of the panel with no change.

[mr2013e]

Re: Lg 50ln5100-ub

im agree with budm.problem can be panel.

[jjanssen7]

Re: Lg 50ln5100-ub

Try unplugging tconn ribbons one at a time. If one side is good and other side has flutter, then it's the panel.

[Fisher77]

Re: Lg 50ln5100-ub

Try unplugging tconn ribbons one at a time. If one side is good and other side has flutter, then it's the panel.

Well when I unplugged the ribbons one at a time, there was no picture on either side. In the myriad of vertical lines, I could still see the horizontal lines that are present when both ribbons are plugged in. Could also see the horizontal lines flashing, so it looks to be a bad panel. I assume the ribbons on the panel are detaching. Would that be the cause of this? Any way to fix?

Pictures are not that great. Best I could do without laying it in the floor.

[jjanssen7]

Re: Lg 50ln5100-ub

In my experience that means a panel fault. I'm surprised that you don't get a picture on the "attached" side when you test that way, but some LG LCDs behave as pictured. I think you may be able to conclude it's (sadly) a panel failure but I'd want others to weigh in before you deliver the bad news. In this case, I don't believe repair is possible.

[Fisher77]

Re: Lg 50ln5100-ub

In my experience that means a panel fault. I'm surprised that you don't get a picture on the "attached" side when you test that way, but some LG LCDs behave as pictured. I think you may be able to conclude it's (sadly) a panel failure but I'd want others to weigh in before you deliver the bad news. In this case, I don't believe repair is possible.

Thanks jjanssen7. I will hold off delivering the news and see what budm, mr2013e, or both have to say as you suggested, although they both agree its a panel fault.

I dont know what happened but its doing this now. I have cleaned and reseated the ribbon cables several times.

[Diah]

Re: Lg 50ln5100-ub

your first post photo there are horizontal line.. and your first test by release ribbon from panel one by one, you have clean white picture. also when you each time release these ribbon it will display different color line. those are enough to tell T_CON Fault .. try replace it before you caused more damage to the set.

[Fisher77]

Re: Lg 50ln5100-ub

Ok here are some pics showing when I have the left ribbon cable disconnected. You can see the line on the white, little harder to see on the pic with the vertical lines, but it is there.

[Fisher77]

Re: Lg 50ln5100-ub

And here are some pics when I have the right ribbon cable disconnected. No horizontal line.

[Diah]

Re: Lg 50ln5100-ub

you damaged the ribbon cable pin pad. the TV age those cable easy to dry out and the silver / Gold pin of them lost the glue to the pad so they moved out or broken. under magnifier inspect them from both side.

[Fisher77]

Re: Lg 50ln5100-ub

you damaged the ribbon cable pin pad. the TV age those cable easy to dry out and the silver / Gold pin of them lost the glue to the pad so they moved out or broken. under magnifier inspect them from both side.

Ok I inspected the ribon cables. No damage found. I inspected the connectors on the boards. No damage found. I swapped the 2 ribbon cables left to right, right to left, and the tv is doing the same as before.

[jjanssen7]

Re: Lg 50ln5100-ub

When you connect both tconn ribbons do you have a picture like when you first received the TV? (just with the original horizontal lines problem?)? If so there is a little tape trick I've learned that you can try. It involves placing a piece of thin scotch tape over the last 8 or so tracks of the ribbon and then reconnecting it... in your case you would do this to your right ribbon because that's the side that generates the horizontal lines when connected. On the right ribbon, try covering 8-10 of the left side tracks and if that doesn't work try 8-10 of the right side.

As always, you are powering off the TV before connecting/disconnecting those ribbons, right?

[Fisher77]

Re: Lg 50ln5100-ub

When you connect both tconn ribbons do you have a picture like when you first received the TV? (just with the original horizontal lines problem?)? If so there is a little tape trick I've learned that you can try. It involves placing a piece of thin scotch tape over the last 8 or so tracks of the ribbon and then reconnecting it... in your case you would do this to your right ribbon because that's the side that generates the horizontal lines when connected. On the right ribbon, try covering 8-10 of the left side tracks and if that doesn't work try 8-10 of the right side.

As always, you are powering off the TV before connecting/disconnecting those ribbons, right?

No that is the wierd thing. With both tconn ribbons connected it is showing those pink bars. When I was messing with the ribbons, I did power the tv off each time. It kinda makes me wonder if I didn't get a ribbon cable crooked when I reconnected them causing something to short out on the tconn board.

[jjanssen7]

Re: Lg 50ln5100-ub

Good thing t-conns are dirt cheap for that model. You'll have to get it back to your "original" screen... I believe the panel had a fault (causing the line). It could have faulted more and be too far gone, or if a replacement tconn gets you back to your starting point, you may be able to extend it's life a little with the tape trick. I've used it on 10-15 LG panels in that series.

[Fisher77]

Re: Lg 50ln5100-ub

Thanks jjanssen7, I ordered a t-conn this morning. Found it on ebay for 6 bucks. After reading horror stories from people getting boards from ebay, I was kinda leery of ordering one off of there. But the seller had a 100% postive feedback rating, and has sold a ton of tv boards, so hopefully it will be a good one. When it gets here I will try the tape trick, and post back.

[Fisher77]

Re: Lg 50ln5100-ub

Ok, the new t-conn came in this morning. Installed it, and of course the same problem which confirms a panel fault. I tried the tape trick. I had to cover 12 of the left tracks, on the right ribbon cable to get a normal picture again. Thanks jjannsen7 for the trick.

Now I have a couple of questions. Out of curiosity, would I have to cover all 12 traces to correct the fault, or could I insulate number 12, then 11, then 10, and so on till the problem is gone?

How long can I expect this to last?

Prolly no clear answer for the second question, but I would like to be able to tell the baseball coach something if possible.

Thanks