Trying to fix an old peavey audition plus...

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by elkym, Oct 19, 2008.

  1. elkym

    elkym Member

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    mostly for the fun of tinkering... maybe because I could use another, more portable amp...

    The transformer is bad, and not bolted very well to the rest of the amp-- possibly why it got killed...

    anyway-- not sure how/where to start...

    I'm looking to find a replacement on ebay or something-- but I don't know what my limits are-- nor do I know how to extrapolate the info. I need from schematics...

    Any help... general advice about transformers-- which one is the output tranny and which is the power tranny? etc.

    send me links, advice, etc...

    Current specs on the tranny aren't something I'm finding...

    20W, 9V RMS, 4 Ohms
    120 VAC, 60 Hz, 50 Watts...
     
  2. mr coffee

    mr coffee Gold Supporting Member

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    call peavey.... or go thru your local dealer
     
  3. elkym

    elkym Member

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    I've tried calling peavey, the tech guy hasn't been in yet... he's always on the line, or gone...
    My local dealer said that he couldn't tell me much, as he didn't repair amps-- always sends them to the nearest urban center... SLC... and since SLC is a good long way from here... I'm trying the DIY route...
     
  4. doc

    doc Member

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    Generally Peaveys are fairly well built, so from your description I wonder if someone else has already been into that amp. Peavey is generally very good with customer service. I'd try emailing. I probably wouldn't bother trying to find it on Ebay - you're more certain to get what you need from Peavey.
     
  5. elkym

    elkym Member

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    From the looks of it, someones been into the amp for sure, or it's just taken a real beating... it's a good 8-10 years old, I'm pretty sure.

    I'm interested in understanding the limits and restrictions around what trannies I could use and the why and how and stuff...

    I'm sure if I could get a hold of Peavey they could give me some specs-- or even order me the part, but that's not all that I want...
     
  6. SatelliteAmps

    SatelliteAmps Member

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    That you don't know the difference between a power and an output transformer makes me wonder whether this is something you can handle. This is a power supply stuff, which means enough voltage to kill you if you don't know what you are doing. The specs you quoted are the specs straight off the speaker (3.2 ohms 20w, 9VRMS), and the line input voltage (120VAC, 60 hz, 50 w). Those are both specs written on the back of the amplifier and have nothing to do with the transformer requirements.

    For that matter, how do you know the power transformer is bad? Have you tested it at all, or is this an assumption because it's not bolted in very well? Just because a solid state amp won't power up, does not automatically mean the power transformer is bad.

    This is a solid state amplifier, so the power supply is going to be somewhere between 9v and about 35v, but which exactly is dependent on the transistors and IC's used in the amp itself. If you shoot too much power in, you will fry chips, too little and the amp won't work properly. You don't need a schematic to get the spec's on the chips. That can all be looked up online. That is the limits, restrictions, the why, and the how.

    Solid state amplifiers are very difficult for amateurs to try to repair without the proper tools and abilities. I highly recommend reading a lot and learning about this stuff way before you bother trying to jump in and fix this amp.

    If this version of the Audition is like the other Peavey Audition models, then there is no output transformer. It's directly coupled to the chip.
     
  7. elkym

    elkym Member

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    Thank you! You've been the most helpful person I've encountered... I plan on being fully informed before I try to actually tackle this... but I usually need a layman's explanation before I'm able to understand a lot of the stuff that I read online...
     
  8. Rosewood

    Rosewood Member

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    Great points from Adam and I would add if you don't completely remove all shorts you could possibly watch your new transformer or chips go up in smoke. I stopped repairing solid state amps because people would not pay for the number of hours it took to make sure the amp was right before you fire it up. I would ask a friend with a variac and some electronic skills to kinda walk you through the repair.
     
  9. donnyjaguar

    donnyjaguar Member

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    In my experience the general failure mode of solid state amplifiers is blown output devices. If you blow an output transistor you stand a good chance of blowing the driver transistor and so on down the line. I guess you could say many failures are catastrophic. It could also blow the power transformer. Generally I test all the devices and remove the blown ones and then power it up to see if there is any voltage. If so, disconnect the tranny secondaries and run for a while with no load. If it gets hot, its probably shagged. Then you have to ask yourself if its worth repairing. I learned all this stuff myself so you can too, but you've a ways to go yet.
     
  10. elkym

    elkym Member

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    Thanks again, guys,
    I'm pretty sure the transformer is bad, the guy at the repair shop tested that first-- just to see-- He said that the loud humming sound that comes from the amp is often enough caused by a bad tranny... The preamp out doesn't work, either...
     
  11. elkym

    elkym Member

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    But perhaps the preamp wouldn't work anyway, if the PT was bad?
     
    Last edited: Oct 21, 2008

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