Help with Power Supply / Inverter

Discussion in 'The Projects Forum' started by JohnnyKarate, Jan 2, 2013.

  1. JohnnyKarate

    Thread Starter New Member

    Jan 2, 2013
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    I am attempting to repair a TV (Insignia ns-32e570a11). Considering the symptoms (power light stays on, screen flashes, no picture) I am suspecting the power inverter is at fault.

    Unfortunately, it appears that the power inverter and power supply are on board on this model (DPS-120RP-1 a). As a result, I am finding it difficult to figure out whether the problem is in fact with the "power inverter" or if it is actually something else, such as the main board.

    Any suggestions? I tried tracking down a schematic for the board, but none is available (company won't release information either).
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    I can get it going, only if you post good pictures showing both sides of the board and all.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  4. JohnnyKarate

    Thread Starter New Member

    Jan 2, 2013
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    Thank you for the posts and I apologize for the delay in responding. I had assumed that I would get emailed when someone posted a reply - I suppose that I will need to check my account setting and make sure that I keep on top of that.

    As for the board, I am still struggling with it. I decided to take a shotgun approach and replace every electrolytic cap with exception of the two largest caps. This has not helped.

    Currently, I am removing the transistors and attempting to test them. My first attempt is leading nowhere however; as I cannot find a datasheet on the transistor and as such I don't know how to test it. AM image is provided, here are the details for clarification:

    - top left corner has marking "O"
    - top right corner has marking "13"
    - center has marking "J"
    - center has marking "SP952
    - center has marking B30H60G
    - bottom left has marking "ON"
    - bottom right has marking "AKA"

    Currently I am just trying to test every component on the board in hopes of finding something useful. Unfortunately, I do not know any better way to approach the board as a whole given that I am failing to reverse engineer it.
     
  5. praondevou

    AAC Fanatic!

    Jul 9, 2011
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  6. JohnnyKarate

    Thread Starter New Member

    Jan 2, 2013
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    Thank you very much for the datasheet, praondevou. I did a simple diode test and this component looks good.

    This is my first full-blown PCB repair, so I apologize for likely missing something. I have tested the 5v out and that is steady. When I power on the PS, the 12v out looks good as well.

    What I have not figured out yet is how to test the signals going out to the lights (the various CCn outs). Without a schematic, I simply don't know what is good/bad here. What I do know is that I consistently get a quick flash each time I power on. Also, one time I accidentally shorted something on the PS and to my surprise, the TV lit up and worked great for about 3 minutes - I even saw the menu. I tried reproducing this accident, but to no avail.

    Any suggestions on how I could narrow my search would be appreciated. I started trying to write up a schematic working backwards from the CCn outputs, but that's a bit out of my league at the moment.
     
  7. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Have you inspected the boards for bad solder joints? Some might only be visible with a magnifying glass. Look for very small cracks.

    Is this your TV? How did the problem start? Did it not very work anymore overnight or did it start failing occasionnally?
     
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