LG monitor power problem.

Discussion in 'General Electronics Chat' started by Αντώνης Τερζής, Aug 22, 2015.

  1. Αντώνης Τερζής

    Thread Starter New Member

    Aug 22, 2015
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    Hey there AAC guys, this is my first post to your great forum.

    So here is my problem.I own a LG 23MA53D tv that I use as a computer monitor. The power cable was a little bit short so I made an extension and it worked like a charm for about a year. So yesterday while I was cleaning somehow the diy power supply extension I had made shorted and a little spark came of(my tv was turned off) after that I tried to turn on my tv but as expected nothing happened.My tv doesn't have an internal transformer. It has an external power brick so I tried to open it and look for any blown capacitors but with no luck. Right now I am ready to cry so I need your help to this problem . thanks in advance!
     
  2. absf

    Senior Member

    Dec 29, 2010
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    What is that external power brick for?

    All my TV are plugged directly to the mains sockets...

    Allen
     
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    absf likes this.
  4. ScottWang

    Moderator

    Aug 23, 2012
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    Take some clear photos will be help for your problem.
     
  5. bwilliams60

    Active Member

    Nov 18, 2012
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    Have you measured the output of your "power brick"? Lets figure out if its that or the monitor first. If it is in the monitor, pull the back off and post pictures of the boards.
     
  6. Αντώνης Τερζής

    Thread Starter New Member

    Aug 22, 2015
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    Thanks for your reply! I'll try to upload some photos of the power brick and the tv's main board.
     
  7. Αντώνης Τερζής

    Thread Starter New Member

    Aug 22, 2015
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    I thought about by I don't have a spare polymeter right now and it is kinda difficult to find one. I'll post some photos tomorrow morning of the board.Thanks!
     
  8. absf

    Senior Member

    Dec 29, 2010
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    Ah... that "brick". It's the same as the one I use on my ASUS laptop.

    As you have already opened it up and found no fuse was blown. Do you have a multimeter so that you can measure if there is anything shorted? Most probably an electrolytic cap or MOSFETs.

    Allen
     
  9. dl324

    Distinguished Member

    Mar 30, 2015
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    I second (or third) checking the power brick. Even if the TV was on, it would have been the brick that was likely to be damaged by a short.
     
  10. Αντώνης Τερζής

    Thread Starter New Member

    Aug 22, 2015
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    Well, I tried to use my laptops but the output wasn't enough to power the monitor. I could find a multimeter but I have no knowledge of using one. I will seek for tutorials in the internet. So you say that I need to find a multimeter and test the capacitor's capacitances?
     
  11. Αντώνης Τερζής

    Thread Starter New Member

    Aug 22, 2015
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    Do you know any possible way to check of the power brick is ok?
     
  12. Αντώνης Τερζής

    Thread Starter New Member

    Aug 22, 2015
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    So here is a quick photo. I am sure you can't understand much from this photo. The brick has three capacitors. You can clearly see the two and the third hidding in the corner.

    WP_20150823_003_1024x575.jpg
     
  13. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    can you take voltage measurements
     
  14. Αντώνης Τερζής

    Thread Starter New Member

    Aug 22, 2015
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    I wish
    I wish I could but I don't have a multimeter available
     
  15. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    So what makes you think you can troubleshoot and fix it?
     
  16. dl324

    Distinguished Member

    Mar 30, 2015
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    Measure the output of the power adapter with a voltmeter. If you're uncertain of what you're doing, you should find someone who does. Even if the adapter is damaged, you could still expose yourself to dangerous voltages if you have it opened.
     
  17. ian field

    Distinguished Member

    Oct 27, 2012
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    Those power bricks invariably have over current shutdown, and are reasonably robust - but a sudden short can damage the secondary side rectifier.

    As always with SMPSU, you have to watch out whether the secondary rectifier is Shottky-barrier type, a fast silicon rectifier will over heat if used to replace a SB rectifier.

    Most monitors with power brick and a lot of laptops I've seen were 19V - I've never seen a TV with a power brick.
     
  18. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    There are TV's with power bricks.
    I have seen Sony using them.
     
  19. ian field

    Distinguished Member

    Oct 27, 2012
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    I didn't say there weren't any - just that I haven't seen one.

    It sort of alludes to the idea that I wouldn't know what voltage a TV brick puts out.
     
  20. Αντώνης Τερζής

    Thread Starter New Member

    Aug 22, 2015
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    Thanks! The first thing I am going to do when I find a multimeter is this.
     
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