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How To Repair Samsung LCD TV With Vertical Lines

By on April 8, 2016
samsung lcd tv repair









I received this defective Samsung model: LA40A650AIRXX which has vertical lines superimposed on to the video signal. The intensity of the vertical lines changes with the RGB signals and very prominent on white video signal as shown below:

samsung lcd tv repair

samsung lcd tv repair verticle line

Since the vertical lines are not in the static location and always changing with the video display so, it is unlikely the LCD panel is at fault. The possible cause could be the main board, T-con board or both. I performed a grey scale test with the same procedure as in my earlier article on gamma distortion.


There is no gamma distortion or noise on the grey scale but RGB vertical lines are being superimposed on it (see photo 1). The intensity of the vertical lines changes with the contrast level as well.

lcd tv verticle lines repair

lcd tv gamma ic

I suspected the gamma IC is faulty although it displayed no gamma distortion. The gamma IC on the T-con board is IC18 with part no. ISL24005. After changing the this IC there is a remarkable improvement on the video quality except for some fine vertical lines still visible only at high contrast level. As I have suspected earlier the main board is also contributing to the problem. Changing the main board will be ideal but may not be worthwhile as the main board is not cheap. By reducing the sub-contrast level and the RGB gain by a certain value in the service mode, the vertical lines are not visible and the reduction in gain and contrast level have not change the video quality significantly as shown below. The customer is very happy and satisfied with the end result as the repair cost does not burnt a hole in his pocket.

gamma ic replacement

Tips: Reworking manually on IC18 is not an easy task due to the QFP packaging being small, thin and leadless. The back of the IC is soldered to the board as well which make it more difficult to remove . After carefully removed the IC without damaging the board, I have a hard time trying to re-align the position of the new IC as the solder pads are underneath and difficult to view from the edges. After a few soldering attempts I managed to re-soldered it.

resolder gamma ic in lcd tv


This article was prepared for you by SK Wong from Malaysia and he graduated from London with a degree in Electronics and Electrical Engineering. He has more than 40 years of experience in the consumer product manufacturing. With the passion to repair electronic products from young , he has been doing it part time until now.

Currently, he can provide turnkey solutions for consumer products including services from idea or concept to design , prototyping , finished products (including electronic,mechanical and plastic parts) and manufacturing.

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Note: You can check his previous repair articles below:




  1. Chris

    April 8, 2016 at 4:25 pm

    Great repair. Well done with nice photos and explanation.
    Sometimes we must make compromise between price and repair results. This was worth the repair I think.
    My best regards.

    • Fortune Gondwe

      December 8, 2022 at 4:52 pm

      Well explained and good job.i have really learnt something.

  2. Humphrey Kimathi

    April 8, 2016 at 4:32 pm

    Excellent work SK Wong, A satisfied customer will always come back and refer others too, Again thanks for keeping the repair cost low in order not to burn a hole in his pocket.
    Regards Humphrey - Kenya

  3. suranga bandara, Suranga Electronics

    April 8, 2016 at 5:43 pm

    Very professional
    Mr, SK Wong,

    you have shown your expertise.
    Good Repair. Thanks.!

  4. moshe jacobson

    April 8, 2016 at 7:02 pm

    Hi SK....this was really interesting as i have a iMAC G5 with a similar problem and the information on the web was all pointing to the replacement of the LCD panel.
    So maybe the iMAC LCD panel includes the electronics and replacing the panel coincidentally replaces the defective chip.

    • skwong

      April 8, 2016 at 10:05 pm

      I have no idea of the IMAC G5 and I guess the IC could part of the panel circuitry.

  5. Hermann

    April 8, 2016 at 9:26 pm

    QFP-packaged ICs are indeed horrible. Especially when they are that small. I have watched a video by Shop Jimmy lately on Youtube. This guy knows how to do it. I think the key is to use just the right amount of solder paste for the bottom pad so that the chip does not float too high on top of the molten solder. It should just sit tight enough to let the contacts take on solder (via the iron), which is applied with a lot of flux gel.

    Check it out:

    • skwong

      April 8, 2016 at 10:08 pm

      I guess you can use similar method as in the youtube to solder. This IC is much smaller and alignment is a bit difficult.

  6. Yogesh Panchal

    April 8, 2016 at 9:30 pm

    Thanks for this tip.

  7. Robert Calk

    April 8, 2016 at 10:35 pm

    Good job, SK. I'm not sure I would be brave enough to solder that IC. But thanks to your tips on using the hot air and the new Hakko soldering iron I bought recently, I can do better soldering now.

    • skwong

      April 9, 2016 at 3:19 pm

      Good luck, I am sure you can pick up the skill and do a good job with the right type of equipment.

  8. Bholanath Adhikary

    April 8, 2016 at 11:02 pm

    Excellent,It is great job.


  9. Humberto

    April 8, 2016 at 11:39 pm

    Well done Mr. Wong, your repair saved a lot of money to the ownwer of the appliance. Congratulations.

  10. mahmoud

    April 9, 2016 at 2:40 am

    Hi SK thanks a lot this is really great repair and very very professional work that you do.

  11. brad

    April 9, 2016 at 7:06 am

    if the vertical lines are static, does that mean the LCD is damaged?

    i have some vertical lines on LCD but i can still see some of the picture behind them

    • skwong

      April 9, 2016 at 3:15 pm

      No not all static vertical lines fault is caused by the panel. The flex cables joining the panel can create static vertical lines. Check the flex cable copper track for damages or short. From my experience I come across the some of the connector cable tracks dislocated and shorted to the adjacent track which resulted in static vertical lines. When the flex cable aged, the tracks bonding has loosened and may shift when you insert it back into the connector.

  12. beh

    April 9, 2016 at 3:07 pm

    Hi Sk
    thanks for this article and your great job on soldering of this smd ic.

  13. Bholanath Adhikary

    April 9, 2016 at 10:37 pm

    You are greats.

  14. Luis Abrenica

    April 15, 2016 at 12:00 pm

    Thanks to SKwong for the tip, I would like to ask where to order spare parts of LCD and LED TV's.

    • skwong

      April 17, 2016 at 11:50 am

      As I have mentioned in one of my previous articles, sourcing components for replacement is more challenging than trouble-shooting the fault. It is not easy to find parts but with some luck you may find some in ebay, element14 ,, RS and China is the best source for LCD components if are able to access to it.

  15. Tito Kanshulu

    April 24, 2016 at 6:41 pm

    Excellent work Mr Wong. The repair saved alot

  16. mahesha

    April 30, 2016 at 12:09 am

    hello sir thanks for the article. i want know how can solder and desolder the smd ic on such a thin pcb board.

  17. Richard Anderson

    May 20, 2016 at 12:19 pm

    SK Wong,
    for many years my company designed and manufactured LCD monitors for military and medical applications. I would say that 95%of vertical line failures were line driver failures on the back side of the LCD panel. You could usually see if the flex circuit on the back side of the LCD had come loose. These panels do generate heat delaminating the flex circuit from the back of the LCD Panel some times component legs lifted. Stabilizing the flex circuit so it doesn't bend then re-soldering the lifted lead.


  18. Wojciech

    April 14, 2017 at 2:49 am

    I have Samsung LE40A786 with similiar problems. Screen in distorted in the same way, menu is distorted, but on-screen-informations like channel number or Info are not distorted. Looks like picture gets faulty before on-screen display (OSD) and after scaler. Is it possible OSD is added in T-Con and T-Con is faulty?

  19. Murali

    January 29, 2018 at 9:42 pm

    Melbon 32 inches vertical failt full lins

  20. Arun Maity

    March 4, 2018 at 4:32 am

    Rev.sir I am Arun live in haldia . West bengal.plese request lg 50pt560 plasma details falt finding. Set on 205;60;5;volt ok stand by 3.3 5.17 voltage ok but no stand by light and remote not working solution tell me Sir.

  21. ergo

    December 28, 2018 at 12:06 am

    pls can you help me how to repair my tv, it shows vertical lines as on the pictures below:


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