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Faulty LCD TV power supply

Discussion in 'Troubleshooting and Repair' started by swenmasterson, Oct 28, 2013.

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  1. swenmasterson

    swenmasterson

    13
    0
    Sep 29, 2013
    Hi everyone,

    I bought an LCD TV of a local auction site thinking I could fix the caps on it and it would work:D Unfortunatelly, the caps were fine (I changed them anyway just to be sure/all the caps with a marker dot have been replaced).

    When you switch on the TV the blue stand-by ligh comes on after about a 5 second wait (way too long in my opinion) and the screen stays black/no sound).

    The seller said it just stopped working over night (did not mention that he tried to repair it:mad:)

    Having looked at the power supply more closely it was obvious somebody tried to repair it already. One of the transistors had been replaced and a capacitor also. I suspect that IC201 had been replaced also - judging from the solder work. Ive circled all of these areas in red. Also IC201 looked to have a black blob like substance on top of it/some kind of black residue(?) - I thought it was damaged but cleaned it quite easily with isopropyl alcohol - now it looks new and I can read the parts number - could this have been a tell tell sign?

    What Ive done:

    1)I checked the N channel mosfet - its fine (reads quite high on the diode test, but shows all the signs of a working mosfet according to a manual I read online)

    2) checked the replaced resistor (should be 10Ohm but is 10,5 - That shouldnt be a problem, right?

    3) I have no idea how to check the IC201 but judging from the working replacement parts I would assume it is functional:

    Anyone have any idea what the problem could be?

    The TV is a Hanseatic LC1910T (Samsung panel), the same TV was also made by Daewoo (DAEWOO DLT-19L2), but no schematics or anything - its a really unknown brand I guess.

    The power supply number is: SHP2204B-301

    The only thread (french) I found on this PS:
    http://www.teleservice-depannage.com/t10916-DAEWOO-DLT-19L2.htm

    Photo album:
    http://imgur.com/a/Qqv1u

    Thanks for having a look at this guys!
     
  2. swenmasterson

    swenmasterson

    13
    0
    Sep 29, 2013
    Ok guys, I went ahead and checked the diodes including the schottky diode and they all seem to be fine. I checked the pins that run from the power supply to the main board that processes video and all of them are giving the right voltage (5v, 8v, 14.5v, gnd etc). Why doesnt the TV work then? Could there be something on the powersupply thath might be doing this? All the voltages are there, the tv seems to be on stand by but wont power on. Another thing I noticed is that no reles are clicking...
     
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