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Sharp LC-30HV4U - Red 3 Pattern Blinking LED Part 2

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    Sharp LC-30HV4U - Red 3 Pattern Blinking LED Part 2

    Previously I posted about replacing all nine 220uf 25v caps on the main board of this TV with new ones but with 35v caps. (https://www.badcaps.net/forum/showthread.php?t=55531)

    It worked for a few days, now it's doing the same thing: it comes on for up to 10 seconds, then shuts off with 3 red LED blinks (constant green means all is well). Keep in mind this is an older TV from 2003, one of the first of its kind. There is no HDMI ports anywhere. In fact, component ports are in a seperate VCR-sized box that connect to the TV via DVI and another cable I'm not sure of.

    Any suggestions are welcome. I got my multimeter ready.

    Here is someone else's video of what my TV is doing:

    https://www.youtube.com/watch?v=09gnxfMZQbQ

    Once the TV is powered, the screen will turn on. After a few seconds, a relay clicks somewhere and the TV dies.

    I believe the power supply is at fault. The issue persists even when the component box is disconnected, power supply connection to the inverters are disconnected, TCON and "PB" connections are disconnected. I also noticed a few things on the power supply board that didn't look right, mainly the dirty or corroded surface mounted "247" components. Examples of this are attached.

    Attached as well are photos of the back of the TV with and without the protective metal shield that covers part of the main and power boards. I also took the time to map out the connections on the power board in question as well.

    I know there is a way to trick a power board into powering itself on in the absence of a main board. I tried this via the "PA" connection but didn't have any luck. The third pin from the bottom reads 6 volts; the rest are 0.

    Any suggestions are welcome. I'm ready with my multimeter.
    Attached Files

    #2
    Re: Sharp LC-30HV4U - Red 3 Pattern Blinking LED Part 2

    I heated up all the capacitors on the main board for the hell of it to see if anything changed, no go. In the power supply board pic above, the single leftmost transformer buzzes for a few seconds upon powerup, gets a little loud and then goes quiet once the TV shuts off.

    Comment


      #3
      Re: Sharp LC-30HV4U - Red 3 Pattern Blinking LED Part 2

      Originally posted by JDC View Post
      I also noticed a few things on the power supply board that didn't look right, mainly the dirty or corroded surface mounted "247" components. Examples of this are attached.
      You mean "274"?
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      Comment


        #4
        Re: Sharp LC-30HV4U - Red 3 Pattern Blinking LED Part 2

        Originally posted by RJARRRPCGP View Post
        You mean "274"?
        You're right, thanks.

        Comment


          #5
          Re: Sharp LC-30HV4U - Red 3 Pattern Blinking LED Part 2

          Bump.

          Comment


            #6
            Re: Sharp LC-30HV4U - Red 3 Pattern Blinking LED Part 2

            Further examination of the power board showed a cap that looks bulged on its side. This is the 22uf 400V cap located near the bridge rectifier. I'm ordering another one plus 2 68uf 450v caps for the bottom left of the board.

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