Viewsonic VG800b power supply noise

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  • sceva
    Senior Member
    • Feb 2010
    • 196
    #1

    Viewsonic VG800b power supply noise

    This one had a couple of bad caps at C4 and C5, and the component to the left of FL1 had a bad solder joint. I replaced the caps and resoldered the joint and it now works. But when it is connected to power and the monitor is turned off there is a ringing(?) noise that seems to be coming from most likely the area in red, but possibly from the area in yellow. I tried the tube to the ear but could not get any closer than that. Are there any common components that most likely could make a noise? Thanks.
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    • Dgtech
      E. Technician
      • Apr 2009
      • 1462
      • Steeler
      #2
      Re: Viewsonic VG800b power supply noise

      I have found caps and transformers to make a hissing noise or a high pitch ring nose.
      The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

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        • sceva
          Senior Member
          • Feb 2010
          • 196
          #3
          Re: Viewsonic VG800b power supply noise

          Originally posted by Dgtech
          I have found caps and transformers to make a hissing noise or a high pitch ring nose.
          I replaced the caps, even the big one, but that did not help. Maybe the transformer?

          I just googled around and saw this:
          Usually, there are 3 reasons why you're hearing that buzzing sound:
          1. Bad filter caps on the input side
          2. Bad diodes, leaky capacitors or bad optocouplers
          3. Loose parts on the transformer that vibrate because of the transformer's magnetic field.

          I will check some more. Thanks.

            Comment

            • Th3_uN1Qu3
              Believe in
              • Jul 2010
              • 6031
              • Romania
              #4
              Re: Viewsonic VG800b power supply noise

              It's usually the transformer or any filtering coils. Some SMPS Shut Up (tm) gets rid of it. Aka brush some lacquer onto the transformer and coils and it's done.
              Originally posted by PeteS in CA
              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
              A working TV? How boring!

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                • jetadm123
                  Badcaps Legend
                  • Feb 2010
                  • 2169
                  #5
                  Re: Viewsonic VG800b power supply noise

                  Try this, using the eraser end of a wooden pencil, stick or any else that's insulated, gently push against the metal frame of the transformer to see if that changes the tone you're hearing.

                    Comment

                    • sceva
                      Senior Member
                      • Feb 2010
                      • 196
                      #6
                      Re: Viewsonic VG800b power supply noise

                      Thanks for the tips. I did not try the lacquer yet... I did try pushing around on things and resoldering but it did not change, except it might be a little quieter now. I put it back into the case and am letting it test for awhile. It is not very noticeable inside the case... maybe I should put some insulation around the board to further dampen the sound! :-)

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