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A Dead LCD brought back to life. Model: LG32LF15R

By on June 29, 2020
1207a pwm ic bad in lcd tv

A friend of mine who works in a company in my area brought his TV for repair and as he explained the problem I realized either it is a power supply issue or main board issue since I did not see any stand by light coming on. It was completely dead.

how to fix lg lcd tv no power

As I took the back cover off and scanned the area with my naked eye, I could not see any marks or any bulging in any of the capacitors.

I checked the fuse but it was intact.

capacitor in lcd tv

As I checked the main capacitors, I was getting about 350 DC volts there which indicate from this point back it was in perfect conditions. I turned the TV off and wanted to make sure the capacitors were discharged; they were still holding charge which is an indicator that something is open along the way. I noticed there was a fuse there next to these capacitors; I checked that fuse (after discharging the capacitors of course), the fuse was open.

fuse open in lcd tv

The logical thing here is to look for the cause of this open fuse and soon enough I was able to find it. It was a Mosfet nearby and as I took it out, it was shorted. The part number is: P9NK65ZFP.

I already have the exact part number in my shop and I installed it on board but I did not power it on because I want to make sure nothing else is shorted.

stp95k65z fet lcd tv

Click on the photo above to access the datasheet

1207a ic shorted

Sure enough, as I traced the pins of the Mosfet I was guided to this area of the board. I found two SMD resistors open, one was 10 ohms and 33 ohms and since these were open, I am almost sure the IC is gone too. The IC: Have these writings on it 1207A and the low reading: PFMW. This IC was so hard to find but when I called my friend who is also a technician he suggested to replace the whole board but when I asked him if he has this IC he answered yes.

I was thinking of replacing these open parts then if that did not work then I will consider changing the whole board.

As I replaced the two open resistors, the Mosfet, the IC and the fuse I added a light bulb to the main fuse and powered up the TV and I could see the stand by coming on.

how to repair lg lcd tv with no power symptom

As I took the light bulb off and put back the actual fuse and powered up the TV, it came on and as you can see connected a source to it. It was working just fine.




Mission Accomplished.

This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.

P.S- Do you know of any your friends who would benefit from this content that you are reading now? If so, forward this website to your friends or you can invite your friends to subscribe to my newsletter for free in this Link.

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

https://jestineyong.com/just-one-bad-led-caused-shut-down-problem/

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18 Comments

  1. Albert van Bemmelen

    June 29, 2020 at 9:19 pm

    I guess that your friend who could provide the needed 1207A IC had bad experiences with fixing this LG TV, why he first suggested to replace the whole board?

    Likes(4)Dislikes(0)
    • Waleed Rishmawi

      June 29, 2020 at 11:15 pm

      Albert: the technician is used to replace the whole board and if I decided to do that I am buying from him. Have a blessed day

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

    June 29, 2020 at 9:29 pm

    I meant replaCe of course (old laptop keyboard, and old fingers LOL).

    Likes(1)Dislikes(0)
  3. Parasuraman S

    June 30, 2020 at 6:34 am

    Your decision to restores its original power supply is really appreciated. That's what a professional would always try to do, to his best! Well done!

    Likes(1)Dislikes(0)
    • Waleed Rishmawi

      June 30, 2020 at 12:28 pm

      Parasuraman: I thought I would give it a try and fix it and that did not work I would then replace the whole board. Finding the ic was the key point to this repair. Have a blessed day my friend

      Likes(1)Dislikes(1)
  4. Greenford William Mafuleka

    June 30, 2020 at 2:42 pm

    Hi Waleed,
    Electronics need technicians who take time find a problem. You and those experienced elders are making good wonders . We learn a lot by exchanging ideas. Regards. Greenford William Mafuleka.

    Likes(1)Dislikes(0)
    • Waleed Rishmawi

      June 30, 2020 at 7:22 pm

      Greenford: yes, the idea to find the fault but sometimes we find the fault but can not find parts to fix that fault: in the case it is ok to replace the whole board...it is a compromise we face in this work but sometimes it has to be done like that to the satisfaction of the customer. have a blessed day

      Likes(1)Dislikes(0)
      • iosef

        September 22, 2020 at 5:36 am

        Tank you gracias

        Likes(0)Dislikes(0)
  5. Mark

    June 30, 2020 at 7:45 pm

    Hey Waleed,
    Good job on the repair! These IC's are tricky little guys, but once you rule out the other components, then they are worth replacement to try and diagnose the fault.

    Likes(0)Dislikes(0)
    • Waleed Rishmawi

      July 1, 2020 at 3:11 pm

      Mark: thanks man. you are totally right. have a blessed day

      Likes(0)Dislikes(0)
  6. JTLiuzza

    July 1, 2020 at 2:18 am

    Hello Waleed,

    I'm new at this and have a question. What made you conclude that the IC was also bad and how did you go about verifying that? Thanks for your articles. They are very helpful to me as I learn.

    Likes(1)Dislikes(0)
    • Waleed Rishmawi

      July 1, 2020 at 3:13 pm

      JTLiuzza: well, since the two fuse resistors nearby were blown, I automatically assumed that. the Line was not shorted but simply bad IC based on what I see on that line.
      I am glad you are learning from the articles. we are here for that and thanks for the encouragement. have a blessed day

      Likes(2)Dislikes(1)
      • JTLiuzza

        July 2, 2020 at 5:29 am

        Thank you. Very helpful. You have a blessed day as well.

        Likes(0)Dislikes(0)
  7. Gassan Ali

    July 1, 2020 at 2:41 am

    A complicated repair! You went along the right lines by replacing the components instead of replacing the board. That's what techs are for. I wonder what made you think that you should trace the pins of the mosfet that finally led you to the main culprit! It's the kind of thinking I want to embody myslef with. Anyway, Enjoyed reading this interesting repair. Have a nice day!

    Likes(0)Dislikes(0)
    • Waleed Rishmawi

      July 1, 2020 at 3:16 pm

      Gassan: well, when replacing the Mosfet and power on the tv and nothing came on, I started checking the same line on that bad mosfet. in other words, do not just look where the fire is but also look for the source of that fire. have a blessed day.

      Likes(1)Dislikes(0)
  8. Babu M.s

    July 1, 2020 at 8:30 pm

    Your way of approaching the fault is fantastic.I have learned many things from your articles.(Since I am regular to read News letter/electronicsrepair) I cannot for get your welding machine repair articles.Thanking you very much for your articles and excepting many more.

    Likes(1)Dislikes(0)
    • Waleed Rishmawi

      July 2, 2020 at 3:23 pm

      Babu: I thank you for the encouragement. I am glad you are learning from the articles so I will try my best to keep it up. you are most welcome and have a blessed day

      Likes(0)Dislikes(0)
  9. Raj

    August 5, 2020 at 9:25 pm

    Great..thanks

    Likes(0)Dislikes(0)

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