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Peavey Classic 30 and Delta Blues hell !

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  • Peavey Classic 30 and Delta Blues hell !

    Hi amp tech Gurus !

    Here's a quick story of what is going on:

    For the past 20 years, my main gigging amps have been a Classic 30 and a Delta Blues.
    Both have had the speakers swapped ( Weber California 15" and a 12" Cannabis Rex ) and retubed with JJ's.
    Both had been extremely reliable and I gave them some much needed TLC a couple of years ago.
    I re-capped both of them with all new Nichicon caps and I figured I might as well do some mods while in there.
    I did the tone stack, overdrive channel input, and the tube board mods according to the Steve Ahola page.
    Those amps sounds so good after those mods !!!


    My party came crashing a couple of months ago !
    While setting up for a gig with the Classic 30, I turned it on and after letting it warm up for a minute, plugged my guitar in. Almost no sound from the amp...
    If you put your ear next to the speaker, you can hear the guitar a little bit but it is whisper quiet, whether on the clean or the OD channel. Very slightly louder on the OD channel.
    I tried plugging into the FX return to bypass the preamp section and same result.
    So I pulled the chassis out after I get home and start looking for a broken bus/jumper wire or anything that looks burnt out but everything looks good.
    I used the multimeter to check all the jumpers and everything looks good. I used the multimeter to check diodes, resistors, etc and they all seem to be fine.
    I tried another set of tubes and still nothing.
    Yesterday, I decided to take another look, even swapping the reverb tank with the delta blues in case that was the issue but same result...
    I can't figure out what the hell is going on !!!

    To add insult to injury, 2 gigs later, my trusted Delta Blues took a crap too !!!!

    I had just finished setting up for a gig with the Delta Blues, sound checked it, sounded great as always.
    Go to start the set... nothing out of the amp. Pilot light is still on. I look at the tubes in the back and all the power tubes are off.....
    Turned the amp off then back on and voila ! The power tubes turn back on... but still not a sound. Try plugging into the FX return... Nothing...
    And unlike the classic 30, this time I cannot hear ANYTHING at all out of the speaker.
    I pulled it apart once I got home and everything looks perfect in there. No broken bus wires, no burnt traces or components, nothing obvious to the naked eye.

    I love working on my gear and have worked on many other amps but this has me banging my head against the wall !!!!
    In the meantime, my bulletproof Sovtek MIG50 is doing a great job but I want my Peavey's back.

    What do the experts think ? Where should I start looking first ???
    I'm just about to throw in the towel and take it to someone else for the first time in 15 years...


  • #2
    The C30 is a simple enough amp, but it is very inconvenient to work on.

    I would:
    verify power amp and preamp individually.
    Bridge FX loop with a cord, any help?
    Solve any dark heaters. If the power tubes are all dark, look for failed solder or broken wire on jumpers between boards, also teh larhe ceraamic fuse and holders.
    Verify B+ everywhere. If you pull any tubes, the rest of that soze will go off, but you can still pull all the tubes, power up, and measure voltages on the socket pins. B+ should be everywhere it belongs.
    Education is what you're left with after you have forgotten what you have learned.


    • #3
      Hey Enzo,
      Thanks for the response.
      Good news is I got the classic 30 back in service !
      I started tinkering around with the chassis out of the cab and noticed I was getting only treble. Messed around with a chopstick around the tone stack and found a brunt/lifted trace on the tone cap after the treble pot.
      A little bit of bus wire and soldering later Et Voila !

      Haven't had as much luck with the Delta Blues though.... Getting a really low/faint sound out of it like the C30 so I suspect a similar issue.
      I'm going to go over every solder point with the iron and some fresh solder and see what happens...

      However, because the cabinet of the Delat Blues is bigger, it's a bit of a pain to connect and disconnect the reverb tank every time.
      Is there a way I can safely run the amp on the bench while bypassing the reverb ?
      I would assume running jumper wires from the in/out of the reverb connectors on the board would work but I'm not sure how that would affect the driver circuit.

      Thanks for the help !



      • #4
        Good luck - I once disassembled and re-assembled a C30 13 times over 2 days trying to find a broken trace/jumper. I'll never get those 2 days of my life back again.

        If you can't find a broken jumper or trace or pad on the main boards, carefully check the 7-strand ribbon cable between the middle (smallest) main PCB and the extn speaker PCB. You may have broken one or more of the ribbon wire connections when working on, or removing/reinstalling the boards (or not).
        Building a better world (one tube amp at a time)

        "I have never had to invoke a formula to fight oscillation in a guitar amp."- Enzo


        • #5
          I am working on a C50 right now and I swear at it every time I need to do anything. What a stupid mechanical design.