What could be the reason for too high voltage from filter caps?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by O RUde, Jun 21, 2019.

  1. pdf64

    pdf64 Member

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    As you got a light bulb limiter then it should be used until the issues have been resolved.
    Does it stay permanently at a high brightness?
     
  2. O RUde

    O RUde Member

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    It isn't at the highest, it lights up when I start the amp, then it dims down. It just seems bright on the pic. The strange thing it works, sort of, when the lamp is used, makes a huge feedback when not.

    The feedback stops when I pull out V3. I have also change the V3's, same thing happens. Still there when I pull out power tubes, one by one.
     
    Last edited: Jun 25, 2019
  3. Tone_Terrific

    Tone_Terrific Supporting Member

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    Oh. Multiple issues.
    Is your nfb loop connected to the proper spot i.e. phase?
     
  4. O RUde

    O RUde Member

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    Last edited: Jun 25, 2019
  5. HotBluePlates

    HotBluePlates Member

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    That shows the OT polarity is wrong. Move the OT primary wires to the opposite power tube socket, reconnect, and the negative feedback loop should be fixed.
     
    Baxtercat and O RUde like this.
  6. O RUde

    O RUde Member

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    I did, and now it works. Thanks all for all help.
     
  7. kinmike

    kinmike Supporting Member

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    I read all the posts but I'm unclear about the final solution. I know you switched the OT primary wires, a very common problem with new builds, but what else needed fixing?

    BTW,
     

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