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1.8V Voltage Regulator IC Problem In LED Monitor

By on April 24, 2015
led monitor repair

 

 

 

 

 

 

 

 

The complaint was no power. This LED Monitor uses an external power adapter and the output voltage was tested good (19 volt DC).

led monitor power adapter

Since the power adapter was tested good, I had to open it up and check on the mainboard.

led monitor mainboard

If you take a look at the photos below, this Monitor consisted only three circuit boards- the mainboard, LED backlight driver board and LED controller board.

 

Since this is a LED Monitor so you would not find an inverter board. Inverter board is for LCD Monitor.

led monitor repairing

Once the metal cover of the mainboard was removed the first thing I do was to check for the SMD voltage regulator ICs. I saw two ICs ie; 1117-3.3 (output 3.3 volt) and 1117-1.8 (output 1.8 volt).

1117-18 ic

I began to test on these two ICs and found the 1117-3.3 was good but 1117-1.8 IC does not produce any output voltage. It has 3 volt input but no output. Both ICs datasheet you can find it from the internet. This was a good sign because if there was no output from this IC means the MCU IC would not work. If the MCU IC doesn’t work means it will not generate any signal to the power LED light.

Before I replace the faulty 1117-1.8 IC I measured between the ground and the IC output (pin 2) with an Analogue meter set to x 1 Ohm. It gave a high and a low reading which was good. If I get two similar low Ohms reading this means there could be something shorted that had caused the 1117-1.8 IC to stop producing output voltage.

a1117-18

It was easy to replace this small SMD IC and after replacement was done and powered On, I could see the blue power LED light.

led monitor repaired

When I measured the voltage it showed 1.837.

led monitor repair

led monitor repairing

If you want to become an expert in LCD/LED Monitor repair you can check out my ebooks below:

http://www.LCD-Monitor-Repair.com

and

http://www.LCDMonitorCaseHistories.com

 Jestine Yong

jestineyong

 

 

 

 

 

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40 Comments

  1. Robert Calk

    April 24, 2015 at 4:36 pm

    Good job Mr. Yong.

    Likes(0)Dislikes(1)
    • Jestine Yong

      April 24, 2015 at 4:42 pm

      Hi Robert,

      You are welcome.

      Jestine

      Likes(4)Dislikes(0)
      • Edward

        April 24, 2015 at 9:35 pm

        Hi ther mr Yong I have this samsung 943NXPlus lcd monitor which only shows a flickering power light and the screen does not light up when I open it I replaced 2 bulged caps but before I removed the caps I heard a huzzing or sizzing sound that's cuming frm the transformer or the inverter transformer and can you tell me if I can replace a resistor fuse wif a normal resisitor please help

        Likes(2)Dislikes(0)
        • Jestine Yong

          April 24, 2015 at 10:20 pm

          HI Edward,

          Resistor fuse is flameproof type and not recommend to use normal resistor which can easily burn.

          Jestine

          Likes(4)Dislikes(0)
      • DIPTEEKANTA MAHAPATRA

        May 21, 2015 at 8:18 am

        dear Jestine yong
        in my CRT monitor screen.a vertical line is showing.and no picture will be shown.what's the matter.can you help me to solve this problem.

        Likes(0)Dislikes(0)
        • Jestine Yong

          May 22, 2015 at 7:41 am

          HI Depteekanta,

          Vertical line is the problem of horizontal section. Try check the horizontal yoke coil area for dry joints and make sure the horizontal yoke coil is not open circuit.

          Jestine

          Likes(0)Dislikes(0)
  2. Albert Hoekman

    April 24, 2015 at 5:05 pm

    Nice explanation, first time I read about this fault. Mostly the problem is with the external power supply.

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 24, 2015 at 5:48 pm

      HI Albert,

      Yes the no power symptom also can be caused by bad mainboard.

      Jestine

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

    April 24, 2015 at 5:28 pm

    Sir thanks your tips.

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 24, 2015 at 5:48 pm

      Hi Yogesh,

      You are welcome.

      Jestine

      Likes(0)Dislikes(0)
  4. Anthony

    April 24, 2015 at 5:29 pm

    Hi Jestine, precision diagnosis and repair...nice work !

    Likes(1)Dislikes(0)
    • Jestine Yong

      April 24, 2015 at 5:49 pm

      HI Anthony,

      Thanks.

      Jestine

      Likes(0)Dislikes(0)
  5. Waleed Rishmawi

    April 24, 2015 at 5:51 pm

    Thanks for the nice article and for the nice photos. congrats on your success. God bless.

    Likes(0)Dislikes(1)
    • Jestine Yong

      April 24, 2015 at 8:48 pm

      Hi Waleed,

      You are welcome.

      Jestine

      Likes(1)Dislikes(0)
  6. yaghob

    April 24, 2015 at 6:09 pm

    hi
    really nice article
    very thanks
    i hope see LCD Monitor Case Histories ver 4! as soon as possible

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 24, 2015 at 9:24 pm

      HI Yaghob,

      You are welcome.

      Jestine

      Likes(0)Dislikes(0)
  7. Phumlani

    April 24, 2015 at 6:18 pm

    Nice Work Sir

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 24, 2015 at 9:24 pm

      Hi Phumlani,
      Thanks.

      Jestine

      Likes(0)Dislikes(0)
  8. moshe

    April 24, 2015 at 9:07 pm

    Hi Jestine
    Nicely put!
    thanks for sharing

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 24, 2015 at 9:31 pm

      HI Moshe,

      You are welcome.

      Jestine

      Likes(0)Dislikes(0)
  9. Humberto

    April 24, 2015 at 10:06 pm

    Hi Mr. Jestine Yong, good repair, you anlaized deeply the Mainboard to find the culprit and finally the LED Monitor was saved from the dump. Congratulations.

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 24, 2015 at 10:17 pm

      HI Humberto,

      Thanks.

      Jestine

      Likes(0)Dislikes(0)
  10. jose antonio

    April 25, 2015 at 2:55 am

    Mr. Jestine great job, thanks for sharing

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 25, 2015 at 8:50 pm

      HI Jose,

      You are welcome.

      Jestine

      Likes(0)Dislikes(0)
  11. Paris Azis

    April 25, 2015 at 4:57 am

    Hi Jestine,

    "Logical thinking = effective troubleshooting"...(Once again confirmed)!
    Good job!

    Best Regards

    Likes(1)Dislikes(0)
    • Jestine Yong

      April 25, 2015 at 8:48 pm

      HI Paris,

      Thanks.

      Jestine

      Likes(0)Dislikes(0)
  12. Ernst

    April 25, 2015 at 6:37 am

    Hi Jestine,

    Thanks for sharing this with us. This way i keep on learning all the time

    Likes(0)Dislikes(1)
    • Jestine Yong

      April 25, 2015 at 8:48 pm

      HI Ernst,

      You are welcome.

      Jestine

      Likes(0)Dislikes(0)
  13. Arshath

    April 25, 2015 at 1:24 pm

    Hi jestine sir.....u are dng ll sir.....i gathered too many information's from u....nice work....thank u sir....

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 25, 2015 at 8:48 pm

      HI Arshath,
      You are welcome.

      Jestine

      Likes(0)Dislikes(0)
  14. Rajesh

    April 25, 2015 at 3:14 pm

    Thanks a lot dear

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 25, 2015 at 8:49 pm

      HI Rajesh,

      You are welcome.

      Jestine

      Likes(0)Dislikes(0)
  15. Veyron

    April 25, 2015 at 7:16 pm

    That was an awesome solution from you again.
    I learnt a lot from your post. But this time I could not understand one part and that's :
    "Before I replace the faulty 1117-1.8 IC I measured between the ground and the IC output (pin 2) with an Analogue meter set to x 1 Ohm. It gave a high and a low reading which was good. If I get two similar low Ohms reading this means there could be something shorted that had caused the 1117-1.8 IC to stop producing output voltage"

    What it mean by "it gave a high and low reading".I mean does the meter shows a high when we first connect to the pin 2 and later drops to a low value or is it like we take two separate readings and first we get a high value and the second time a low value. Please explain me this, its the first time ever I read anything like this.
    If possible can you upload a video or photos explaining hows this done.

    Likes(0)Dislikes(0)
    • Jestine Yong

      April 27, 2015 at 7:19 am

      H Veyron,

      It means that if the dc output line is shorted there will be two similar readings. If it is normal it will usually have a higher ohm and lower ohm value when you reverse your probe and test. I suggest that you visit this link for more information https://www.jestineyong.com/audio-interface-repaired/

      Jestine

      Likes(1)Dislikes(0)
  16. Aziz

    April 26, 2015 at 6:13 pm

    Hello dear Mr.Yong , thanks for sharing different types of electronic device repairing.God bless

    Likes(1)Dislikes(0)
    • Jestine Yong

      April 27, 2015 at 7:14 am

      HI Aziz,

      You are welcome.

      Jestine

      Likes(0)Dislikes(0)
  17. Abdul Kader

    November 17, 2015 at 6:41 pm

    Thank u boss

    Likes(0)Dislikes(0)
  18. Feroz tejani

    September 7, 2017 at 2:04 am

    Sir can you please explain the different voltages of an lcd/led tv motherbord like 3.3v ,1.8v etc and to which sections these voltages are used for

    Likes(0)Dislikes(0)
  19. diwa

    September 18, 2017 at 10:05 pm

    sir,
    my acer ph660 monitor voltage is unstable even in direct line without vga attached the screen shakes and rolls, could you suggest me is it the capacitor problem? i m in trance.

    Likes(0)Dislikes(0)
    • Jestine Yong

      September 21, 2017 at 11:09 am

      HI Diwa,

      Without hands on assessment I would be really guessing on what might be wrong. Unstable voltage problem can be caused by many factors. I suggest that you check the output filter capacitors with esr meter.

      Jestine

      Likes(0)Dislikes(0)

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