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Dell SE198WFPf - No standby

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    Dell SE198WFPf - No standby

    No standby light and no power.

    Wish I had a schematic for this board as I'm sure it would make things a lot easier.

    I have replaced the caps on both the power and mainboard but no change.

    Voltages on cable coming off of the power board read as follows (plugged in, no power):

    1) 5.03V
    2) 5.03V
    3) -1mV (milli)
    4) -1mV
    5) 139.5mV
    6) 2.355V
    7) -9.6mV
    8) 0.65V

    There are no markings as far as what pins are what. Pressing power button does not change any values.

    CN104 on the mainboard which goes to the buttons read as follows:

    1) 3.3V
    2) 3.3V
    3) 3.3V
    4) -1V
    5) Jumps around 2.6V
    6) 0
    7) 0
    8) 0

    Again, pressing power button changes nothing.

    While testing diodes, I did come across one value that seemed strange. D852, which is near the bottom left corner of the transformer reads 0.433V one way (good), but also reads 0.911V the other way.

    I'll be honest, I'm still a novice but definitely willing to learn. I've learned a lot already but still missing quite a bit. Any ideas on what to test out next?
    Attached Files

    #2
    Re: Dell SE198WFPf - No standby

    The power supply is working otherwise you will not be getting the 5VDC to run the main logic board. The power supply is an always on power supply which supplies 5V for the main baord and 16~20V for the inverter backligts circuit.
    It sounds like you have main board problem.
    Never stop learning
    Basic LCD TV and Monitor troubleshooting guides.
    http://www.badcaps.net/forum/showthr...956#post305956

    Voltage Regulator (LDO) testing:
    http://www.badcaps.net/forum/showthr...999#post300999

    Inverter testing using old CFL:
    http://www.badcaps.net/forum/showthr...er+testing+cfl

    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
    http://s807.photobucket.com/user/budm/library/

    TV Factory reset codes listing:
    http://www.badcaps.net/forum/showthread.php?t=24809

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      #3
      Re: Dell SE198WFPf - No standby

      In your opinion is it even worth trying to diagnose the mainboard? I don't see anything physically wrong with it. From my limited experience there seems to be so much going on (controllers and such) that it would make it hard to pinpoint the exact problem -- at least on this mainboard.

      If you have anything worth trying I'd love to give it a shot.

      Comment


        #4
        Re: Dell SE198WFPf - No standby

        Just to update this. I replace the mainboard and the unit now works fine. $15 on eBay.

        Comment

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