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Peavey Basic 60 repair

Discussion in 'Amps and Cabs [BG]' started by tenaciousjg, Mar 22, 2006.

  1. tenaciousjg


    Mar 22, 2006
    Hey everybody! Long time reader, first time poster.

    I've got a Peavey Basic 60 (classic solid-state goodness!) that has conked out and I'm wondering if anyone may have repair advice. I'm pretty handy with instrument-based stuff like changing pickups and pots, and I've tweaked some FX units before, so I feel fairly handy with a soldering iron and thought I'd give home repair a go this time.

    The problem appears to be the inputs - the amp powers normally, the speaker pops and you can hear the normal background noise, but volume knobs, hi/low ins, preamp out all fail to get any sound happening. I've got it pulled apart and have been examining the circuit board - nothing is obviously shorted, broken, or burned.

    I don't actually know the circumstances of the failure - I picked it up as a fixer and don't know if it quit suddenly, or was intermittent for a while or what. If that helps!

    Anyone have this amp, or even had this problem before? I welcome your thoughts and tips!

    Thanks a ton,

  2. I have a Basic 50 (same thing, slightly different front panel and cosmetics). You should try inputting something into the effects return and see if it amplifies. That would let you know if the power amp stage is okay. I'm far from a seasoned tech, but it could be something as simple as an open circuit (disconnect) right at the input jack, or maybe the effects return switching jack is hung up in the "connected" mode. Also, try connecting a very short signal cable between the effects send and return. This would test for a bad effects return jack switch.
  3. georgestrings

    georgestrings Banned

    Nov 5, 2005
    As whacker has alluded to, one of the jacks in those loops could very well be your problem - if one of those jacks isn't functioning properly, it can act like an open circuit... Sometimes in those situations, all it takes is to plug in and unplug a patchcord a few times to "unstick" the offending jack - other times you'll have to run a patch to complete the loop, and still other times, the jack will have to be replaced to make ANY noise out of it... If it has Pre Out/Power In, and you have another amp to use, I'd test out both of those sections 1st - that'll tell you alot... With the Peavey amps I've owned, "Patch" is a loop between the input and the preamp, and "Pre Out/Power In" is between the preamp and power amp sections - I'd look at whatever those loops are called on your particular amp...

    - georgestrings
  4. Yes, to concur with George, the jacks I was really referring to are indeed called pre-amp out, power-amp in. On the 60 they're two separate jacks, and on my 50 they're consolidated into one 3-conductor (TRS) jack. Good place to start troubleshooting.
  5. mtengaio


    Feb 17, 2009
    I'm having the same issues with my Basic 60: The amp powers up fine when turned on, but when I plug into the either the High or Low Gain inputs, nada, which is interesting because I only use the Low Gain Input jack. Just for the hell of it I plugged my bass right into the Power Amp In input and got sound from my bass. I know my potentiometers need to be cleaned but I'm not even getting sound from the High or Low Gain inputs which is making me wonder if I need new input jacks on the Input Gains.

    Any suggestions?
  6. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    If you've cleaned out the jacks on the back, and still no good, an amp tech is your ONLY option. I work with electronics all the time, but amps are a very specialized field, best left to the pros. I wouldn't even consider digging into one myself.
  7. As a temporary test, take a regular guitar cable, plug one end into the "Out" jack, and the other end into the "In" jack. Then with another cable, plug into the "front end" of the amp (the normal High or Low gain inputs). See if you get sound (at a normal level). If you do, chances are the jack with the switch (most likely the "In" jack) is at fault. If it's too much hassle to fix it (more cleaning, wiggling, or replacement), you could run it regular with the jacks patched like in the test.
  8. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    All good advice above. Try the effects loop jacks as described above. Do beware of high voltage inside the chassis if you try to fix this. It sounds like the power amp section of the circuit is OK, from your description. Do you get any static or change in the amount of hiss when you twist the knobs back and forth? That's another way to localize a preamp problem.

    A basic op amp preamp would not be hard to diagnose, but it's a lot easier if you have an oscilloscope, and I'm generally hesitant to recommend any work inside an amp due to the presence of dangerous voltages.

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