Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

[fredtred]

Hello!
I have been trying to solve this issue the past 12 months to no avail. I have been a lurker here during that time but finally decided to post my problem and see if anybody knows a solution.

Problem
My tv (OLED55CXPUA) has an issue where it displays horizonal lines of dotted artifacts.

(See Attachment 1)

Self Diagnosing
After a very long troubleshooting period I traced the issue to the T-Con board. If I gently flexed/bend the board I could make the display go from GOOD to BAD and vice versa. I have ruled out the connectors/wires being the source of the issue.

See video example here: https://photos.google.com/share/AF1Q...UwaE51cmZHazRR

Video Explanation: I am gently bending the board to make the screen go from BAD to GOOD and back.

Attempted Solution 1: Pre-Bend the T-con Board
Using washers under the pcb at its screw holes I gently I "pre-bent" the t-con board so the display was good. However after a few hours the screen would always go back to bad.

Attempted Solution 2: Reflow the T-con Board
I work with an electrical engineer at work. He recommended trying to reflow the board as it seemed to be a broken connection somewhere. He reflowed it for me. This worked at first, however again, after a few hours the screen went back to bad.

Attempted Solution 3: Buy a new T-con Board
I bought and tried installing 3 different replacement t-con boards. Each one fixed the original issue. No matter how long I used the tv, the original horizontal dotted artifact lines NEVER came back! However each board resulted in vertical banding and dark spots.

(See attachment 2)

Based on my reading through this forum I found these posts which suggest vertical banding is unavoidable when just replacing the t-con board.

Post 1: https://www.badcaps.net/forum/showpo...3&postcount=47
Post 2: https://www.badcaps.net/forum/showpo...53&postcount=9


My Actual Question
With the replacement t-con boards the resulting banding/dark spots are too noticeable and annoying to be an acceptable fix. So I'm wondering either...

1) Is there a way I can fix the original horizontal dotted artifact problem of my original t-con board?

or

2) Is there a way for me to "calibrate" one of my new t-con boards so the banding/dark spots go away?

Thank you very much for any help!

[Diah]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

put yours original T-CON in place and play this test photo ( copy it to usb stick and play it )

show the result with clear focused photo of the displaying screen... you may need to wait if the issue didn't show immediately

[fredtred]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

Hi Diah, the photo is attached.

[Diah]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

keep the image playing.... take any solid linen, like pieces of wood with smooth surface or school line meter for example , put it on the surface of the screen under the line and make little Gently push on the screen surface... see if the second line will disappear or not.... you may try this at many different places on the screen

[fredtred]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

Just tried this. I can take a video if you would like. However pressing into the screen like this had no affect on the artifacts.

[Diah]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

i asked you to do last test because i have before similar issue..you have only horizontal double... and from top ro down the double line are different showing on.. clear or less .. this can tell some where damage on screen front glass layer which the vacuum between linear sheet over OLED Cells. get in miss.. .. when you pend the screen chassis from the back side ( you were thought its T-CON loss contact ) it show good picture.. but after while when the screen work. because of vacuum lost. and cells heat the air will expand and make the sheet far a way from each other.. so the issue noticeable... this is one issue could be

second could be indeed T-CON.... if you want to use the 2 3 4 T-CON you have... you need after install it... downgrade the firmware of the TV to lower version.... then upgrade it.. so the firmware section of T-CON and Main boards will matching same version the displaying you have wrong before was this not matching firmware between replacement T-CON and main boards

hope this will help you

[Davi.p]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

You miss the brand , is it LG?

[fredtred]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

@diah thanks. i will install one of the new tcon boards and will try to downgrade the firmware. is this the procedure I should follow?

https://www.avsforum.com/threads/gui...-only.3217168/

@davi sorry, yes it is LG.

[Davi.p]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

Some similar models service manual says after tcon replacement must do a VCOM adjust, but i never seen it explained (pieces of poop), i searched also youtube but nothing.. this is much probably the right thing, not risky ones like downgrading, things made by geeks with no support and hard to do without years of knowledge.. if you want, try to access service menu and search for the VCOM stuff, do some photo eventually.. the tv needs a recalibration of VCOM, every oled panel i think has a complex map of VCOM values, maybe pixel by pixel, cause each panel is different from the other, this is also why so big memories on board.. the second chance is give original tcon to a service person and do a reballing of every bga chip, CPU, EMMC, RAM, unless you are able to find which one defects but i think is not possible.. take into consideration the last is probably the long lasting one because LG is famous of bad BGA solder jobs and replacement tcon will probably do the same..
*Vcom calibration: it's not strange that it needs tv connection with a propietary software and must be done by instructed service tech.. these are hard beasts, so keep into consideration to ask LG centers...ù
*third chance: give original tcon and one repl. tcon to a tech to make emmc swap... this is the easiest way to solve.. not the best maybe..

[Diah]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

@diah thanks. i will install one of the new tcon boards and will try to downgrade the firmware. is this the procedure I should follow?

https://www.avsforum.com/threads/gui...-only.3217168/

you can try this method... also there Apache server method.. search after..
by the way.. if you play the test image,, and apply pressure on the Main boards at the area where the 2 LVDS cable go to T-CON & the 2 sockets of LVDS, if there any change...?
did you own service remote control..!! to send command IN_STOP to set the the Tv to shipping status.. and to read T-CON firmware via EZ_ADJ & IN_Start

[fredtred]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

I apologize for taking long to respond. Finding time to work on this was tough this week!

Update

@davi Interesting, I was not able to find VCOM adjustment in the service menus though.

@diah Yes! I was able to get a service remote (I downloaded the android LG Service app, works well). So I tried what you suggested. I installed my replacement T-Con board and upgraded the firmware in attempt to make the t-con and main board have the same versions. This did not work sadly (see ATTACHMENT 1). I'm assuming the below 2 specs are the ones that are suppose to match? Can you confirm this?

Source PCBA PID
T-Con PCBA PID

Also I tried to apply pressure around the LVDS cables on the main board like you suggested. This had no affect on the picture.


General Question

After looking more at my original “BAD” T-Con board, I would guess its problem is a bad solder joint somewhere. I think this because I can consistently make the picture go from bad to good by bending the pcba in the area shown in ATTACHMENT 2. Assuming this is true, my question is, if I wanted to find this bad solder joint, which PCB component do you think is the most likely one to have this bad solder connection and be the cause of the bad picture (horizontal dotted lines in ATTACHMENT 3)? The ram? EMMC? CPU?

[Diah]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

1-attachment 1 , i assume for one of yours replacement t-con.. its look good picture, no issue. after upgrade need to send IN_STOP. that's all
2- attachment 2, the original t-con yes its look BGA issue, cover the area with plaster to hold all parts in place.. and apply hot air gun on the area until the plaster burn ( i used always the paper one which used at car painting ).. let the heat go only on the main chips and the other DDR chips. leave it cool complete then carefully take out the plaster , always see if there any part lost and stayed clued on the plaster clue surface.. or give it to one do BGA for them in professional way.

[Davi.p]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

Plaster??! oh my god..

O.P.: in the service menu it shows the replacement tcon is a wrong type and does not match, pid= part identifier

for the original tcon it must be reflown more the 4 ram chips at the sides.. if it works needs a cpu dissipation enforcement

[fredtred]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

Just to recap my two plans are...

PLAN A:
Reflow original T-con board to fix the original issue with the horizontal line artifacts

PLAN B:
Find a way to transfer the calibration data from the Original t-con to the New t-con. Either by copy/pasting the data electronically or physically de-soldering the EMMC and re-soldering it to the new t-con.

For Plan A, I will try to re-flow some of these components. I just need to find a way to borrow this equipment. I will work on this.

For Plan B. I tried IN-STOP and the two PID's still do not match. I want to check my understating. Are you saying that during the TV's assembly at the factory every individual tcon-panel's "calibration data" is recorded and stored on LG's servers? And that data is tied to its PID? And that I can re-download this "calibration data" to my new t-con board from LG's server? Are you saying once the PID's match the vertical banding will go away?

If this understanding is wrong. Can you remind me why do we care if the PID' match?

[Davi.p]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

Oh my god.. you are really backwards in the repair field.. i suggest you search a good serious repair center, these are delicate beasts, you cannon begin neither a simple reflow.wihout many previous experiences.. unless oled tv costs like a chips bag in USA..

[Diah]

Re: Physically bending the T-Con board creates horizontal dotted lines on OLED55CXPUA

Just to recap my two plans are...

PLAN A:
Reflow original T-con board to fix the original issue with the horizontal line artifacts

PLAN B:
Find a way to transfer the calibration data from the Original t-con to the New t-con. Either by copy/pasting the data electronically or physically de-soldering the EMMC and re-soldering it to the new t-con.

For Plan A, I will try to re-flow some of these components. I just need to find a way to borrow this equipment. I will work on this.

For Plan B. I tried IN-STOP and the two PID's still do not match. I want to check my understating. Are you saying that during the TV's assembly at the factory every individual tcon-panel's "calibration data" is recorded and stored on LG's servers? And that data is tied to its PID? And that I can re-download this "calibration data" to my new t-con board from LG's server? Are you saying once the PID's match the vertical banding will go away?

If this understanding is wrong. Can you remind me why do we care if the PID' match?

for yours plan B... you have SPI/NOR 8 pins on the T-CON all firmware parts and Parameter of panel saved on... copy and flash never worked... just remove the complete SPI to the replacements... also after this done IN_STOP must be done