Busted amp on Peavey PV 118D

Discussion in 'Electronics & Electrics' started by johnd16, Jan 25, 2019.

  1. johnd16

    johnd16 Member

    Joined:
    Apr 18, 2008
    Messages:
    104
    Hi all,

    I have a Peavey PV 118D sub that won’t power on. Initially, I thought it was just the fuse as it was blown. I replaced the fuse, but it immediately blew when powered. On further inspection of the PCB boards, I noticed what looks like a blown varistor. I’ve attached some photos. I’d say there’s been a power surge at some point. What I don’t know is the condition of the rest of the components.

    I’ve requested the circuit schematics from Peavey, yet to get a response. I tried googling a replacement for the amp module, but nothing comes up.

    Has anyone had experience fixing powered speaker systems?

    Cheers,
    John

    https://imgur.com/a/kTTTUrp
     
  2. merlin13

    merlin13 Member

    Joined:
    Apr 12, 2003
    Messages:
    1,840
    Location:
    back in BrizVegas
    Mmmm, C91 does look like it threw itself on the grenade. But with that board designation it'd be dependent where it is in the circuit whether it's a in-series varistor or rranzil or a parallel capacitor. Obviously no actual component identification left on it, right?

    So cut/unsolder it from the board and give it to Mr Multimeter to see if it's Ye Good Olde Dead Short or not and work out if it's in line or across a power feed. If it's across then you might bo Good To Go for a scary power-up.

    But if it's in series then then personally I miiiight not be brave enough to power the rest of the circuit back up after you do remove it/replace it with a shunt, unless I had one hand on a mains variac.

    Don't forget to poke around The Usual Suspects - diodes, transistors etc, eyeball caps etc etc etc. If that "thing" strapped to the heatsink is a FET then strip that off the board for a test as well.

    And could also just be me/my eyes, the angle of the piccy, but the soldering on the leg of L8 (R27 end) looks a bit sus as well. So while you've got it in bots check for dry joints everywhere, especailly around the power supply/control stage.
     

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