How To Repair LG LCD Monitor- No Display With Good Power Output Voltage

By on August 9, 2016
repair lg lcd monitor

 

 

 

 

 

 

 

Fault Symptom: No Display With Good Power Output Voltage

lg lcd monitor repair

Customer walked into my workshop with an LG Flatron W1643c Monitor with above said fault symptom. So I have received the monitor for repair and given token to the customer about estimation period.




In order to confirm the problem I have attached the power cord to the monitor and powered it On. I am not getting any symptom of life, LED power indication was not lighted up. So I opened up the casing and do the visual inspection first on the circuit boards.

This monitor is using external power source working on 12V power adapter. First of all I have checked power adapter for 12V and found OK. Now checked PCB by solder side seems ok no burning mark and no dry solder.

fix lcd monitor board

Now I turned the PCB on component side, look what I seen.

how to repair lcd monitor

fixing lcd monitor

There was one Square IC marked with U201 some of the pins look like burnt. So I have checked under magnifier glass and it was not burnt marks but some sticky substance was there.

lcd monitor MCU IC

I cleaned the pins of IC with turpentine and applied some fresh solder. After the cleaning process, now I decided to check the status of monitor by applying power, hence I have connected the power cable and turning on the power.

lcd monitor screen repair

The LG LCD Monitor came back to life with power LED indicator was glowing.

repairing lg monitor circut board

lg monitor no display

I found the pin out detail of the IC “NT68167HFG” on the net as follows. Marked with red box pins cause shorting on the logic board.

nt68167 datasheet

Note: The power LED signals are coming from this MCU IC so if this IC does not work means the LED would not light up. So you may be thinking it was the fault of the power supply. The best way to confirm is to measure the DC supply input voltage to MCU IC.

yogesh

This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.




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Note: You can check his previous repair articles on LCD Monitor in the link below:

LCD Monitor With Hazy Display Repaired

No Display In ViewSonic LCD Monitor VA1930wm Repaired

and you may check out my ebook on LCD/LED Monitor repair:

led monitor repair

 

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22 Comments

  1. Tito Kanshulu

    August 9, 2016 at 2:28 pm

    Good work Yogesh. Should we say that those sticky substances, found on the ic,were in the form of glue which shorted the pins of the ic or some substance dropped on the ic?

    Likes(3)Dislikes(0)
    • Yogesh Panchal

      August 12, 2016 at 12:51 am

      Mr.Tito,
      Thanks for the comment.
      I think it may be due to some insect droppings/urinate or like,though i did not find any insect residue because some one who has open this monitor for repair before me has cleaned every thing from in side.

      Likes(0)Dislikes(0)
      • gaurang Patel

        August 7, 2018 at 12:24 pm

        hello sir i have lg LCD Lm156wh1. which has the same ic nt68167h. i m getting problem in LCD when i connect the VGA cable and power cable it shows the LCD red light blinking continues and on screen it show blank (black). i remove it out and only connect the inverter cable it shows white light. when i connect the data cable it continues blinking the red light. so what could be the problem..
        please sir give me the solution if you have.

        Likes(0)Dislikes(0)
  2. Albert van Bemmelen

    August 9, 2016 at 2:36 pm

    If the sticky substance that caused the shorting Pins came from some kind of insects we better prepare ourselfs for an invasion? According to previous articles they cause for millions of damage on repair costs. Good job Yogesh and thanks for the schematic.

    Likes(2)Dislikes(0)
    • Yogesh Panchal

      August 12, 2016 at 12:52 am

      You are right Albert,
      thanks for comment.

      Likes(0)Dislikes(0)
  3. Waleed

    August 9, 2016 at 4:35 pm

    good article. thanks for sharing

    Likes(0)Dislikes(0)
    • Yogesh Panchal

      August 12, 2016 at 12:53 am

      you are welcome Waleed,

      Thanks for comment.

      Likes(0)Dislikes(0)
  4. Parasuraman S

    August 9, 2016 at 5:10 pm

    Your expertise is what made the troubleshooting so simple and easy!

    Likes(0)Dislikes(0)
    • Yogesh Panchal

      August 12, 2016 at 12:54 am

      Sir,
      Thanks for comment.

      Likes(0)Dislikes(0)
  5. Anthony

    August 10, 2016 at 6:23 am

    Great repair Yogesh, Thanks for sharing.

    Likes(0)Dislikes(0)
    • Yogesh Panchal

      August 12, 2016 at 12:54 am

      Anthony,
      Thanks for comment.

      Likes(0)Dislikes(0)
  6. Gary Gemmell

    August 10, 2016 at 9:26 am

    Nice quick diagnosis and fix - if only all fixes could be like this!
    Well spotted Yogi!

    Likes(0)Dislikes(0)
    • Yogesh Panchal

      August 12, 2016 at 12:58 am

      Mr. Gary,
      yes the the weight of "could be" is more than Human expectations.

      Thanks for comment.

      Likes(0)Dislikes(0)
  7. Luciano Khware

    August 10, 2016 at 2:41 pm

    Yogesh,
    Thanks for sharing your repair experience!!

    Likes(0)Dislikes(0)
    • Yogesh Panchal

      August 12, 2016 at 1:00 am

      Mr.Luciano,
      Thanks for comment.

      Likes(0)Dislikes(0)
  8. suranga bandara, Suranga Electronics

    August 10, 2016 at 4:43 pm

    The quick trouble shooting. nice repair Mr-, Yogesh,

    Thanks for sharing it with us.

    Likes(0)Dislikes(0)
    • Yogesh Panchal

      August 12, 2016 at 1:01 am

      Thanks Suranga.

      Likes(0)Dislikes(0)
  9. reza

    August 11, 2016 at 4:50 am

    Hi
    Very Good

    Likes(0)Dislikes(0)
  10. Yogesh Panchal

    August 12, 2016 at 1:02 am

    Mr, Reza
    Thanks for comment.

    Likes(0)Dislikes(0)
  11. Raju Varghese

    August 14, 2016 at 5:06 pm

    Hai Yogesh,
    Good Day!!!
    good attempt and excellent troubleshooting .
    Thank you for sharing.

    Likes(0)Dislikes(0)
    • Yogesh Panchal

      August 16, 2016 at 12:07 am

      Raju,
      Thanks for the comment.

      Likes(0)Dislikes(0)
  12. mohsen

    January 18, 2018 at 11:10 pm

    I have problem with my lg screen same like one in the topic , when i power it on it gives me a white screen then slowly go to black color and check signal cable appear but the right side still white , i need help plz

    Likes(0)Dislikes(0)

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