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mission 5e3 problems

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  • mission 5e3 problems

    Hey amp experts, a couple questions from a novice...
    I built the amp, did all the voltage testing, almost all came out pretty spot on or at least close enough, and the amp actually works and all, but there are a couple things I know are messed up, but am not sure how to fix.
    First- there is a lead going between two lugs of the power tube sockets, and they are supposed to have the same voltage, but don't. one is 23 volts, the other is 19. how is this possible?
    Also, there is a terrible hum that actually makes the whole chassis vibrate. this is killing me. I've checked out all the grounds and think they are are all grounded correctly.
    anybody think they can help out? I want to try to get this done meself before I pay to get it corrected.
    thanks in advance

  • #2
    Post some pictures of the chassis and wiring layout. I'm sure the folks here will help debug it.

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    • #3
      Without seeing the actual amp, the only way I can think of, where lug 8 on one tube being 23v and the other tube's lug 8 being 19v, is if the jumper between lugs 8, or one of the 100 ohm filament balancing resistors, is not connected to the tube right.... it seems like one tube's cathode has a different total resistance with respect to ground in order for there to be a 4vdc difference.
      The lugs 8 of both tube sockets are tied right together with a stout single piece of wire, right?

      The bad hum is also an indication of a miswired circuit.... possibly related due to the other issue at hand.

      My offer still stands to have you send it out for a look see if you pay the shipping both ways.
      Bruce

      Mission Amps
      Denver, CO. 80022
      www.missionamps.com
      303-955-2412

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