"Re-Capping" An Amp

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Stan Malinowski, Apr 10, 2003.


  1. Stan Malinowski

    Stan Malinowski Silver Supporting Member

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    When amp technicians "re-cap" an amp do they:
    1) Replace just the electrolytic caps on the power supply?
    2) Replace all electrolytic caps (Power supply + bypass caps in the pre-amp stages)
    or
    3) Replace all electrolytic caps AND the non-electrolytic coupling caps?

    Thanks In Advance For Any Answers.
     
  2. VaughnC

    VaughnC Supporting Member

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    When techs refer to recapping an amp, I think most techs would just replace the electrolytics in the high voltage power supply because the take more strain than the others. However, to be on the safe side, all electrolytics should be replaced at roughly 10 year intervals, including the bias supply filter & the cathode bypass caps (which are reletively inexpensive once you already have the amp apart). Unless there's evidence of DC leakage, I can see no reason to replace coupling caps as they aren't prone to drying out like electrolytics, and some say that "aged" coupling caps actually sound better as they can develop some internal resistance over time, supposedly sweetening the sound.
     
  3. THLH

    THLH Member

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    You should always ask. Most will say filter caps. If the amp is 10 years old, the filter caps need to be done. If the amp is 20 years old or older, they should all be done.
     
  4. LHanson

    LHanson Member

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    I am trying to rehab a Bandmaster, circa '65. Where is a good place to get the PS caps? (20 microfarad, 525 volt)
     
  5. Blue Strat

    Blue Strat Member

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    ALL electrolytic caps (especially the bias cap which, when it fails can take out your power tubes and output transformer) should be replaced every 10 to 15 years. Coupling and tone caps may never need to be replaced but should be checked for (electrical) leakage.

    Mouser.com has every conceivable Sprague Atom cap for recapping a Fender amp.

    Mike K
     

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