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M3 AO29 capacitor replacement

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  • M3 AO29 capacitor replacement

    Hi,

    on

    http://www.stefanv.com/electronics/h..._overhaul.html

    I found instructions for replacing capacitors of an AO29 amp. In the photo, the replacement cap for c64 should be seen. But I don't understand, because that silver cap on the photo is c64 in my opinion. Am i wrong?

    Greetings
    Christian
    You may only view thumbnails in this gallery. This gallery has 1 photos.
    1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend Solo

  • #2
    Yes - C64 is the radial cap. The silver cap is C67 (I don't have an updated schematic to confirm it) which is the cathode bypass cap for V10. This was added on later versions of the amp. You can tell which one is C64 because it is part of the PS back bias circuit which generates the negative bias voltage for the 6V6's as the plus side of the cap is connected to ground.

    Edit: C67 & 70 were added to the bass amp circuit. The M100 version of the AO-29 schematic in the service manual shows it.

    Hammond Organ Service Manual - Models M M2 M3 M-100 : Hammond Organ Co. : Free Download, Borrow, and Streaming : Internet Archive
    https://archive.org
    Service manual for the repair of Hammond Organ models M, M2, M3, M-100.




    Jim

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    • #3
      Ok. Thanks for the information. In my case, an older em version (ao29-1f), it should be normal then to see only one silver cap in that region, which should be c64. I read 25v, 25uF. By the way, that cap measures 44uF (+76%) ....and C30 measures 39uF instead of 25uF (+56%). It should be a good idea to replace them, right?

      greetings Christian
      1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend Solo

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      • #4
        Go ahead - can't hurt.
        Jim

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