Are these signs of defective capacitors?

Discussion in 'General Electronics Chat' started by capacapa, Mar 31, 2012.

  1. capacapa

    Thread Starter New Member

    Mar 31, 2012
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    I'm new in electronics in general, so bear with me please.

    I've seen before blown capacitors with bulging in the middle or even open. but on this board, I notice little bulges on the 3 edges of the 1000uf capacitors. when I use ohm meter to check on board, I see it is charging slowly.

    this is a board for monitor.
    pictures:

    http://i42.tinypic.com/33y25gh.jpg
    http://i39.tinypic.com/8xopkz.jpg
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    That is a bit hard to say.

    Caps do not usually bulge form the edge. Since the center is much weaker than the edges.

    Can u unsolder them and look at the bottom for electrolyte leakage ?
     
  3. capacapa

    Thread Starter New Member

    Mar 31, 2012
    17
    1
    thanks a lot for the answer. I ll do that once I find the solder gun. (someone borrowed it)

    this board by the way is the power supply of the monitor. when I turn power on the led light works,but nothing on screen. it likes not detecting signal, then it automatically turns off (this is a feature when not detecting signal). the led light and buttons control connected to the other board (not the ps one)

    do you think in this kind of cases, a defective cap in the power supply unit can still cause the issue. or impossible?
     
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    It is problem with the boost +B.

    If you never fixed a monitor u might dunno what I am saying.

    And yes it could be a cap related problem but rare.

    Do this test and lemme know.

    Keep the monitor off for an hr or so.
    Get a PC, first connect the PC to a working monitor and bring the resolution to the VGA standard, that is 800 by 600 at normal refresh. This will make sure that any monitor will atleast give a display if it works.

    Next without turning the PC off disconnect the vga cable and connect to ur broken one. Keep the monitor off while u connect VGA. Next make sure the power switch is off form the monitor and connect monitor power code.

    Put ur arm across the screen. Ur arm means between wrist and elbow. Close to the screen. To do this u must have some hair on ur arm. Keep the arm close to monitor screen about an inch. If u don't have hair get a monkey.

    Next switch on the monitor and see if the hair is attracted screen at power on. If the monitor HV is active at turn on u will feel ur hair stand up due to static discharge. U won't get any shock or anything if u did not disconnect any internal tube ground cables. Either way u should not turn on any CRT tube with it's HV ground disconnected. It's rather dangerous and U will blow a component some way most of the time if u did.

    Post back the results. then I can tell u what u could do. If you have a DMM and some skills with CRT's
     
  5. capacapa

    Thread Starter New Member

    Mar 31, 2012
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    It's LCD monitor. I did try to test with lower resolution, the problem it turns off automatically . this is a feature in it that when no signal is detected, it turns off. the monitor though had issue before it went all dark. sometimes when I push the switch, the led appears instead of blue very bright . and the screen shows too bright white-pink color all over the screen less than a second then turns off.
    this still occurs sometimes.
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    The it is a DSP issue.

    Do u know how to measure voltages using a DMM
     
  7. capacapa

    Thread Starter New Member

    Mar 31, 2012
    17
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    yes I know and can do that. so you are saying the issue likely in the signal processing board?
     
  8. evilclem

    Member

    Dec 20, 2011
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    It's not the power board, if you see the no signal message then the power is working fine. Sounds like a transient or something through the VGA cable has fried the micro (or other part) on the signal input board.
     
  9. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Gimme some nice high res pics of the signal board from both sides.

    No glare or blurry or out of focus pictures.
    and please check PIC's before posting
     
  10. capacapa

    Thread Starter New Member

    Mar 31, 2012
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  11. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    For the ti,e being this will do, but I might need some more light on the next pic.

    Gimme few hrs, check back later

    {ed}

    U need to do better, pictures are out of focus. it seems u have edited the pics and saved causing loss of quality.
    If you wanna me to help u, I will need high resolution pictures so I can zoom in to and mark the points for u to check.

    Get better lighting and when u post lemme know the connector details.
     
    Last edited: Apr 1, 2012
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