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static from Champ 600

Discussion in 'Glowing Bottle Tube Amp Forum' started by MikeBee, Apr 10, 2021.

  1. MikeBee

    MikeBee TDPRI Member

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    Hi all, I have a Fender Champ 600. Recently it started making a staticky noise. Sounds like the white noise of a TV when the channel quit broadcasting at night. It is intermittent. The volume of the static is low and doesn't change regardless of amp or guitar settings. I have turned on/off many of the lights in the house with no change. Any ideas what I should be looking for??
    Thanks, MikeB
     
  2. kbold

    kbold Friend of Leo's

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  3. MikeBee

    MikeBee TDPRI Member

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    Thanks for the link. Amp makes noise with guitar not plugged in also.
     
  4. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    Clean the tube pins/sockets.
    Try different tubes.
     
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  5. Willie Johnson

    Willie Johnson Tele-Holic

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    Mine had the same thing--tried different tubes, no dice. On a lark, I did the tone stack and NFB bypass mod and it went away. Not a tech, so I don't know what might have gone bad further down the signal path, but it worked.
     
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  6. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    I can speculate that the *fix* @Willie Johnson did to his champ originated as a bad solder joint.

    If changing tubes and cleaning the pins/sockets does not solve your issue ime you could have a bad solder joint or possibly a bad resistor. Basically all of the speculation revolves around a bad connection after the volume control.
     
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  7. Willie Johnson

    Willie Johnson Tele-Holic

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    Amp sounds really great now--added a Jenson Mod speaker, put in Fender grille cloth, and altered/cut down the back panel.
     
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  8. fraser

    fraser Tele-Afflicted

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    Long shot here,
    And it seems youve solved the problem.
    But mine came with sheilding tape, on the underside of the top.
    The tape overlapped on the sides some.
    I kept hearing a slight static kind of thing happening,
    I dont recall how i tracked it down, but somehow that sheilding was the problem.
    Maybe making intermittent contact with part of the chassis, i dont know.
    I tried tightening bolts, i tried properly grounding it to the chassis, i even tried taping it firmly in place, not that it was loose.

    this was before id done any mods, it was brand new.

    in the end i just yanked it out, problem solved.
    A mystery not worth the time spent chasing, to me.
     
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  9. MikeBee

    MikeBee TDPRI Member

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    So I pulled the chassis out for a look. The blue circle shows a spacer of some type. It is the same on 3 of 4 mounting bolts. The blue arrow shows the spacer missing. The chassis has warped a little as a result. Should it be that way? Are the laminations supposed to be grounded to the chassis? It just doesn't look right. The mounting nuts/bolts all show the paint blobs not broken, must have left the factory that way.

    I think the output transformer has been rubbing slightly on the larger speaker, so it will get moved.

    Visually, I saw no solder joint problems.

    I was a bit paranoid of residual voltage in the caps. Found ~ 15 volts in the system and used a resistor to bleed them down to nothing. I was expecting a lot more voltage.

    I have new tubes ordered. Will move the OT farther from the speaker and main transformer. This also has the shielding tape, I will play with that later if I get nowhere.
    upload_2021-4-11_16-38-27.png
     
  10. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    That does seem odd, but I wouldn't expect that to make static. Static is usually a tube or resistor issue.
     
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