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Help with Carvin Legacy please - newbie

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  • Help with Carvin Legacy please - newbie

    Hey guys. I just stumbled onto this forum and you guys seem to know a thing or two. I've got a bit of an issue that i can't figure out.

    I've inherited this basket case of a Carvin Legacy. When I received it there were no power tubes in it and the output board was fried (appeared to be a filament short since that pin on v7 was melted clear through the board also knocking out the filament 100 ohm resistors). I got carvin to send me a new output board and popped it in and plugged up with a new set of EL 34s. Got the bias to about 38ma and all looked well. Started to play through it and the volume was very low. As I turned up the volume a loud popping/squealing sound started coming out if I played more aggressively and if i played lightly the volume was still very low/compressed.

    I couldn't find a single bad component in the amp save the OT. The OT measures about 35 ohms from B+ to either plate. That seems normal, but B+ on the tranny to ground only measures about 25K ohms. That seems very low and kinda like a short in the OT core.

    My question: Does this sound like a case of dead OT or do you guys think it might be something else? If you've seen this before, you help would be greatly appreciated.

    PS - I don't claim to be an amp tech. I'm a guitar tech by trade but I do most of the work on my own amps. I would like to get this one running without buying needless parts.

    Thanks in advance!

    Jon B

  • #2
    Sounds like a failed output xfmr to me. Rule out the front end by putting a signal into the effect return....if it still has the same behavior I'd bet that xfmr ate it. Check screen voltage at the tube sockets and make sure thats where it should be while yer in there.
    The farmer takes a wife, the barber takes a pole....


    • #3
      Thanks for the help! I've got an OT from a crate blue voodoo that I'm gonna try tonight just to see if that cures it. If so, does a Hammond 1650R sound like it will do the job? I've used that one in a project amp before.