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Magnavox 42MF230A/37 no picture no sound!!

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    #1

    Magnavox 42MF230A/37 no picture no sound!!

    Hello I have a Magnavox 42MF230A/37 its a plasma. When I turn it on the red standby LED turns blue and I hear the relay click and that's it. After I turn it on at the controls on the TV, the only way I can get it to turn off is by unplugging it.

    I found and replaced 4 bad caps three on the power supply board and and 1 on the Y main board. still no picture or sound.

    If anyone can help that would be amazing.
    Thanks RJR
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    #2
    Re: Magnavox 42MF230A/37 no picture no sound!!

    Originally posted by RJR View Post
    Hello I have a Magnavox 42MF230A/37 its a plasma. When I turn it on the red standby LED turns blue and I hear the relay click and that's it. After I turn it on at the controls on the TV, the only way I can get it to turn off is by unplugging it.

    I found and replaced 4 bad caps three on the power supply board and and 1 on the Y main board. still no picture or sound.

    If anyone can help that would be amazing.
    Thanks RJR
    The service manual is here. Dowmload it, study it, then test the output voltages of the power supply. If they are good, the fact that you cannot turn the TV off from either the power button or the remote indicates a problem on the Small Signal Board or one of the sub-boards. Those boards should be well documented in the manual.

    I would question if it is worth putting a great deal into that TV unless you are sure it has very low hours. That uses a very early plasma panel.

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

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      #3
      Re: Magnavox 42MF230A/37 no picture no sound!!

      Well I've got good voltage going to and coming out of the sub power supply board and good voltage going to my main power supply but nothing coming out of it. So that sounds like a good place to start. The TV was free got it from a friend so I've got nothing in it but some time and a few caps.

      Thank you sooo much for your help!! I'll be posting again if that fixed it or not.

      RJR

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        #4
        Re: Magnavox 42MF230A/37 no picture no sound!!

        "Hello I have a Magnavox 42MF230A/37 its a plasma. When I turn it on the red standby LED turns blue and I hear the relay click and that's it. After I turn it on at the controls on the TV, the only way I can get it to turn off is by unplugging it."
        I just fix my TV today.same model # and same problem You have .I found bad diode on Power supply board supply 155V/VE voltage for driving X board

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          #5
          Re: Magnavox 42MF230A/37 no picture no sound!!

          Originally posted by dzooem View Post
          I just fix my TV today.same model # and same problem You have .I found bad diode on Power supply board supply 155V/VE voltage for driving X board
          I have the same modle with the same problem. I went over the power supply 3 times, "155V/VE" does'nt seem to be a part number, or a location.

          Could you give me a hint on what kind of diode I'm looking for, or it's location?
          I back tracked the X sus board plug and could'nt find any bad diodes. Then I checked every diode on the PS.

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            #6
            Re: Magnavox 42MF230A/37 no picture no sound!!

            Looks like my problem is different but same "LED goes blue, get a click, but no picture or sound"

            My Y main has two open burnt resisters. There fairly high wattage, 3-5 watts or so, lifted off the board.
            I backed pinned what I could get to and identify on the power supply. It seem's to have power where it should. So the Y board must be keeping the TV from powering up. Does this sound right?

            Comment

              #7
              Re: Magnavox 42MF230A/37 no picture no sound!!

              Y sustain board LJ92-01200A has a shorted D5009 Diode, and R5028 & R5090 are burnt open. It looks to be tired into a 7815 voltage regulator.
              I checked all the cap's and fuses and looked for shorted semiconductors, fet's, diodes, 7815 and looked for bad solder joints on the Y board and power supply and any thing else I could find. I cant find any other bad parts on this board.
              I replaced the bad diode and resisters. They just burnt up again.
              Any one know how to check that big STK under the heat sink? Thats the only thing I did'nt meter. But the parts that are frying dont seem to be related to the STK pack.
              Last edited by jeffescortlx; 02-17-2012, 04:11 PM.

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                #8
                Re: Magnavox 42MF230A/37 no picture no sound!!

                This plasma panel is very problematic. Google the Coppell TV Repair Blog for information on locating shorts on the Y-Sustain and Y Buffers.

                PlainBill
                For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                Comment

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