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Samsung 940NW LCD Monitor Repaired

By on October 30, 2015
samsung lcd monitor repair








The SAMSUNG TFT-LCD Monitor Model 940NW of this story belongs to my 6 years old son.

The complaint was impossible to watch a steady video-out, because it was blinking all the time.

samsung 940nw lcd monitor repair

It’s the time to dismantle the device, and I’m honor of being the first person in opening this Monitor.

lcd monitor repair

Till here all the plastic covers were taken out carefully and  please do not use hard force otherwise you will damage the plastic clips. Now it’s time to check on the electronic circuits.

repair lcd

Once the metallic covers are out the PCBs can be separated (only two PCBs).

samsung lcd monitor board

In this PCB (SMPS) there were three bulged e-caps (820µF/25 x 2 and 470µF/25) and many cold solder joints.

cold solder joints

The three bulged e-caps were substituted for three similar in good conditions, the rest of the e-caps were checked with the Blue ESR Meter and all of them were ok. All the cold solder joints were fixed with fresh tin. But I decided to clean the golden contacts of the LCD Display with a Pen Eraser.

eraser clean circuit track

When everything was concluded the Monitor was armed again and look at the result.

lcd monitor repaired

Now my child is very happy and smiling a lot because his Monitor is working fine now.












This article was prepared for you by Humberto Rodriguez, one of our ‘Master Authors’ from Cuba.

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Note: You can check out his previous repair article below:




  1. Muftah

    October 30, 2015 at 2:01 pm

    Hi Rodriguez.... well done.

    • Humberto

      October 30, 2015 at 8:58 pm

      Thanks Muftah

      • Amir Mukhtar

        November 11, 2015 at 3:26 pm

        Thanks you Mr. Humberto Rodriguez
        Keep sharing you expertise with us .

        Amir Mukhtar
        Karachi. Pk

  2. Albert van Bemmelen

    October 30, 2015 at 3:48 pm

    Hi Humberto, nice repair. Many times it is always those e-caps. Apparently the larger oil (HV) filled capacitors, as can be found in washing machines etc., never dry out as fast as the normal electrolyte capacitors do. But I could be wrong there? I tried for fun to google the Flying Eagle pen eraser you showed (from England?) but no luck.

    • Humberto

      October 30, 2015 at 9:04 pm

      Well Albert, when I got home today I'll look for the country of manufacturation of the Pencil Eraser showed (it's really unredeable the country) which I always keep in the drawer on my work table

  3. Suranga Electronics

    October 30, 2015 at 4:42 pm

    Good Repair MR.Humberto

    • Humberto

      October 30, 2015 at 8:48 pm

      Thanks Suranga, my son is very happy now. I had to give him my Monitor in the meantime I was repairing his Monitor

  4. Yogesh Panchal

    October 30, 2015 at 5:11 pm

    Humberto, Good JOB & Now Computer Operator looks Happy!!

    • Humberto

      October 30, 2015 at 8:41 pm

      Of course he's happy Yogesh; he only uses his PC for PC games and watching cartoons. Thanks.

  5. Anwar Shiekh

    October 30, 2015 at 8:03 pm

    I have 2 LCD monitors that needed capacitors replacing, and some time later started flashing subtly (but only on low brightness); I then treated all contacts (including the ribbon) with silicone oil, and that seems to have solved the problem. I have since run them overnight on an VGA tester circuit (less than $5 on ebay) to see if the problem is really gone.

    • Humberto

      October 30, 2015 at 9:06 pm

      Thanks Anwar

    • Albert van Bemmelen

      October 30, 2015 at 11:59 pm

      Hi Anwar. $5 dollar is very cheap but I made my own VGA Tester with a 12 MHz quarz on a overclocked PIC 16F84 from a Russian author. And with a simple up and down pushbutton I can produce about 15 different test screens.

      After programming the PIC with the right .Hex file and placing it on a cheap wired pcb board, it is now a terrific VGA monitor tester.
      I have the information to build one from a internet link from about 5 years ago. So I do not know if that link still exists?

  6. William

    October 30, 2015 at 10:57 pm

    Nothing more rewarding than the smile of a satisfied customer.

    Good job.

    • Humberto

      November 3, 2015 at 12:07 am

      Thanks William, you are 100% right.

  7. Parasuraman S

    October 31, 2015 at 7:20 am

    Good Job! It is always a thrill to do something for our children and see their innocent happiness! My two grand children throng me with petty repair jobs of their toys and I have seen the grin in their faces whenever I attended to it to their satisfaction. The way they poke in and want theirs to be attended on priority, shows how confidently and unconditionally attached they are! Pl keep it up!

  8. beh

    October 31, 2015 at 2:40 pm

    Hi Humberto
    good job and thanks

    • Humberto

      November 5, 2015 at 3:15 am

      Thanks beh

  9. Paris Azis

    November 2, 2015 at 2:11 am

    Good job Humberto. Thank you for sharing it.


  10. Humberto

    November 5, 2015 at 3:19 am

    Thanks Paris, I'll keep sharing my experiences.

  11. Robert Calk

    November 10, 2015 at 10:39 pm

    Good job, Humberto.


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