55LM4600 bad panel?

[Daveleone]

Hi all!

I have a 55LM4600. The backlights turn on, but there is no picture. I've tried replacing both the main board and the T-Con already (actually tried 2 different replacement main boards and 2 different replacement T-Cons), but no joy.

When I initially received the TV it would turn on and display a bunch of vertical lines on the screen (unfortunately, I don't have a picture of this) of different colors. I can no longer reproduce that pattern, even with the original boards. Now, whether I put in a new main board, new T-Con, or both, or use the original boards, I get the attached image. A black screen with a couple of vertical gray bars.

Is this a bad panel?
Anything I should try/test before scrapping it?

Thanks!
--Dave

[ivtec]

Re: 55LM4600 bad panel?

Bad panel.

[Diah]

Re: 55LM4600 bad panel?

you need to go back to the point when it show colored vertical lines.. which now changed to gray because you have now damaged ribbon cable or LVDS.

put back the original boards.. and take out both ( ribbon & LVDS ) and inspect them under loop of any damage to the contact pins from both sides of them.

[Daveleone]

Re: 55LM4600 bad panel?

you need to go back to the point when it show colored vertical lines.. which now changed to gray because you have now damaged ribbon cable or LVDS.

put back the original boards.. and take out both ( ribbon & LVDS ) and inspect them under loop of any damage to the contact pins from both sides of them.

Ok, I checked both ribbon cables and the LVDS cable, and the traces look fine. I even tested each trace for continuity using my multimeter, and there are no broken traces. I also checked the connectors on the main boards and tcons for damage and found none.

I am still unable to reproduce the original colored vertical lines. I have 3 main boards and 2 TCons right now. Here are the results:

Original Main / Either T-Con: Backlight does not even come on. Pressing the power button on the front panel has no effect. (Original main board is dead)
Main #2 or #3 / Either T-Con: Backlight comes on, but only displays the gray vertical bands as in my original picture. Pressing the power button on the front panel turns the backlight off and on (power button is working).

[Diah]

Re: 55LM4600 bad panel?

I am still unable to reproduce the original colored vertical lines. I have 3 main boards and 2 TCons right now. Here are the results:.

so the main boards photo at yours first post belong to replacement one?

can you disconnect one ribbon cable from t-con to panel at once and see if you get half clear white screen.. if the answer yes... then you need to send IN_STOP command via IR apk for android or diy we had uploaded over here many time... or service RC. code after command 0,4,1,3 to roll up main firmware and t-cone firmware parts too and register both at FW.

EDIT as the photo at yours first post indicated the version of T-CON FW 3.00.70.. if you replaced t-con with different version this will resulted issue too.. IN_STOP could help or update to last firmware or downgrade help too.. i would like to see the color lines back.

[Daveleone]

Re: 55LM4600 bad panel?

so the main boards photo at yours first post belong to replacement one?

Correct. I've attache a photo of each of the boards I have here (including the original non-working/no backlight main board) and the original t-con here for reference.

Just to recap:
1) main_ORIGINAL + any tcon: no backlight (dead main board)
2) (main_NEW1 OR main_NEW2) paired with (tcon_ORIGINAL OR tcon_NEW): results in backlight and gray vertical bars.

can you disconnect one ribbon cable from t-con to panel at once and see if you get half clear white screen.. if the answer yes...

Ok, I did that with each ribbon cable individually. Left ribbon disconnected resulted in a few vertical lines on the right side of the screen (LEFT_ribbon_disconnect.jpg). Right ribbon disconnected resulted in the exact vertical lines that this TV originally had when I received it (see photo RIGHT_ribbon_disconnect.jpg)!

Do you think IN_STOP 0,4,1,3 will correct this? or? If so, I'll try to get a hold of a phone with an IR blaster and give it a shot.

Thanks again!
--Dave

[Diah]

Re: 55LM4600 bad panel?

Do you think IN_STOP 0,4,1,3 will correct this? or? If so, I'll try to get a hold of a phone with an IR blaster and give it a shot.

Thanks again!
--Dave

Okay, the test you did right now with out feeding any signal ? if yes. we need signal or just press menu on the RC.. we need to see the action of picture..

IN_STOP at LG platform always good answer after replacing boards... as it will align main boards and t-con together via FW.

[Daveleone]

Re: 55LM4600 bad panel?

Okay, the test you did right now with out feeding any signal ? if yes. we need signal or just press menu on the RC.. we need to see the action of picture..

Yes, that first test of disconnected ribbon cables was with no input. I tested again with an input and again with trying to bring up the settings menu, both with the same results as before (no change to the lines on the screen).

I will try IN_STOP next. Need to charge up my old Galaxy S5 phone w/IR blaster first

[Diah]

Re: 55LM4600 bad panel?

Yes, that first test of disconnected ribbon cables was with no input. I tested again with an input and again with trying to bring up the settings menu, both with the same results as before (no change to the lines on the screen).

I will try IN_STOP next. Need to charge up my old Galaxy S5 phone w/IR blaster first

yours result what you wrote are mysterious LOL ::: so no image at all you have...

at time yours S5 back to use .. you need to take out the speaker and the metal shield covered the edge boards of the panel.. who know what do you have there ... or some one cut COF ribbon..LOL please tell here always with photos..

[Daveleone]

Re: 55LM4600 bad panel?

yours result what you wrote are mysterious LOL ::: so no image at all you have...

Sorry if it was not clear. Test results:

1) LEFT_tcon_disconnected, with input from Android TV box: same image as LEFT_tcon_disconnected.jpg.
2) LEFT tcon disconnected, press Menu/Settings button: same image as LEFT_tcon_disconnected.jpg.
3) RIGHT tcon disconnected, with input from Android TV box: same image as RIGHT_tcon_disconnected.jpg.
4) RIGHT tcon disconnected, press Menu/Settings button: same image as RIGHT_tcon_disconnected.jpg.

Summary: no change to results even with input.

at time yours S5 back to use .. you need to take out the speaker and the metal shield covered the edge boards of the panel.. who know what do you have there ... or some one cut COF ribbon..LOL please tell here always with photos..

Just want to make sure I understand - you would like me to remove the bottom metal shielding and take a picture of the panel edge boards (that the TCON ribbon cables are connected to) so you can see them, right?

Thanks!
--Dave

[Diah]

Re: 55LM4600 bad panel?

Just want to make sure I understand - you would like me to remove the bottom metal shielding and take a picture of the panel edge boards (that the TCON ribbon cables are connected to) so you can see them, right?

Thanks!
--Dave

yes... i think you too never take a look there

[Daveleone]

Re: 55LM4600 bad panel?

Ok, I tried IN_STOP.

1) Plugged in both tcon cables (and LVDS cable is connected).
2) Plugged in TV. Power & backlight turned on (vertical lines on the screen)
3) Pressed IN_STOP, 0, 4, 1, 3.
4) TV turned off. Red standby light turned on.
5) Turned the TV back on using the Power Button on the remote.
6) No change. (still have the vertical lines on the screen)

Did I do it right? If so, it did not fix the problem. Next step, I will take pictures of the edge connector boards.

[Diah]

Re: 55LM4600 bad panel?

Ok, I tried IN_STOP.

1) Plugged in both tcon cables (and LVDS cable is connected).
2) Plugged in TV. Power & backlight turned on (vertical lines on the screen)
3) Pressed IN_STOP, 0, 4, 1, 3.
4) TV turned off. Red standby light turned on.
5) Turned the TV back on using the Power Button on the remote.
6) No change. (still have the vertical lines on the screen)

Did I do it right? If so, it did not fix the problem. Next step, I will take pictures of the edge connector boards.

yes IN_STOP correct.... but you dont got any image after the set turn on this is my point of mysterious... go head to show and inspect the edge boards of panel

[petehall347]

Re: 55LM4600 bad panel?

something changed .way too many variables unless you first changed all boards then swapped back to original . like sometimes one bad board will damage another board sort of thing .

[Daveleone]

Re: 55LM4600 bad panel?

go head to show and inspect the edge boards of panel

Just to follow up on this, the I uncovered the boards on the panel and they are toast (the traces on the panel ribbon were melted). I decided to scrap this TV for parts.

Thank you for the help.

[Davi.p]

Re: 55LM4600 bad panel?

This was almost obvious since the first post.. sorry to become here late...