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Problem with an old MXR clone.

Discussion in 'Effects [BG]' started by pricey, Jul 21, 2008.


  1. pricey

    pricey

    Jun 6, 2008
    I have an old MXR distortion clone by Coron, its in a black metal case with gold writing which is pretty battered. The case reads DISTORTION 1 and the board says DT-05. I got it for 20 quid in a junk shop a while ago.

    It hasn't been used in a while, and I pulled it out the other day to have a go with it and now when I put the input jack in, the red light comes on but the switch has no effect, the light just stays on, and no sound is output from the pedal. It's been stored in its box and I didn't leave a battery in it, the new battery is brand new.

    Does anyone have any idea what it could be? I took it apart and made sure all the connections are sound and they are. The only thing is that the LED is a little loose on the board and if you wiggle it, it goes on and off, this is simply a loose connection, its always been like that, and it has no effect on the fact that no sound is output from the pedal.

    I'm thinking maybe a problem with the switch? But if the pedal is always on it doesn't explain the lack of output =(

    Thanks for reading hopefully you can help, I'd love to get this going again, it had a lovely dark sound perfect for bass (though it was originally designed for guitar) kinda sounds like a Marshall Guvner
     
  2. SpankyPants

    SpankyPants That's Mr. SpankyPants to you.

    Aug 24, 2006
    Brooklyn, NY
    That's the luck of the Irish!
     
  3. pricey

    pricey

    Jun 6, 2008
    What?
     
  4. pricey

    pricey

    Jun 6, 2008
    Okay, a bit of a breakthrough, I tried shorting out random contacts on the underside of the board and then bam I get a mad high pitched whistling sound, I take the screwdriver away, and the sound stopped, and now I have output again. The switch works, as in when I press it, the sound gets louder depending on the position of the LEVEL pot but does not become distorted. The light is still constantly on.

    This is really annoying me hah.
     
  5. SpankyPants

    SpankyPants That's Mr. SpankyPants to you.

    Aug 24, 2006
    Brooklyn, NY
    Yes.
     
  6. pricey

    pricey

    Jun 6, 2008
    Yeah, if anyone would like to make a helpful comment =)
     
  7. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    More than likely there is a weak solder joint connecting to the switch (perhaps even indirectly, i.e. before a component that directly connects to the switch. The switch itself is likely to be faulty, or at a minimum dirty. Try spraying some contact cleaner into the switch and all the pots and jacks, and work them back and forth to clear the dirt. Then use a magnifying glass to examine all of the solder points that connect somewhere near or on the footswitch. Make sure there are no ground traces/wires severed anywhere.
     
  8. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Oh, and don't mind Spanky, he's just acting as the town drunk until Nad gets back. :D
     
  9. SpankyPants

    SpankyPants That's Mr. SpankyPants to you.

    Aug 24, 2006
    Brooklyn, NY
    Zing!
     
  10. JanusZarate

    JanusZarate Low End Avenger

    Feb 21, 2006
    Petaluma, CA, USA
    Nad vanished?!? :eek:

    He must've bought that GK amp I suggested to him.

    He might be gone for a long time. :D
     
  11. pricey

    pricey

    Jun 6, 2008
    Yeah, what happens to it now is weird, sometimes you plug it in and it works, but is really quiet, you definatly hear a distorted sound, but its so quiet, even with everything maxed. Or sometimes you plug it in and you get a full volume sound but no distortion. You can't have both, and I don't know what makes it swap from one to the other. Also sometimes when you shake it, it makes a really high pitched whistling sound.

    Nothing is shorting against the case because I totally took it apart and ran it out of the case and it does the same thing.

    Broken pot? Damaged cap? Blown chip?
    Any ideas?
     
  12. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Pots do fail sometimes, and they certainly can cause this sort of thing. One occasional problem is a bit of metal inside the pot housing shakes into a spot where it shouldn't go and causes a short; also internal parts can wear down or corrode.

    Caps can die of old age. Also they die surprisingly often due to being actually counterfeit, manufactured cheaply at a low operating tolerance and sold marked with a high operating tolerance and a fake brand name.

    Chips do blow, but you'll typically see marks from that. Brown scorch marks around one or more legs of the chip, smoky white marks of the body of the chip, or sometimes even a small chunk blown out of the chip -really!

    Any part can fail, really. Also the very most common failure is a weak solder joint, and those failures can even be microscopic. Often the cracks/gaps are just small enough to where you need a magnifying glass. Look for solder which is dull, crusty, frosty looking instead of smooth and silvery.
     
  13. pricey

    pricey

    Jun 6, 2008
    Okay thanks for the advice I am determined to get this pedal working again and will try all you suggested!

    I'm sure its not the pots now because I tried shorting across their terminals and still no distortion! So I'll check all the solder joints next.
     
  14. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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