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MXR Phase 90 problem

Discussion in 'Effects [BG]' started by The Lurker, Oct 15, 2005.


  1. The Lurker

    The Lurker

    Aug 16, 2002
    Ankh-Morpork
    ran into something odd when I turn this pedal on-- a pulsing, high-pitched whine or feedback sound and the bottom drops out. No phasing sound. Haven't run into this before. I tried running directly from the bass through that to the amp, no feedback/whine but didn't sound itself. I tried moving it around to put it after different pedals and swapping cables and pots on the power line, but got the same result. Anyone run into something like this before? It does it regardless of whether or not the pedals ahead of it are on or not.

    Current pedal setup is+ Boss TU2-->Digitech Bass Squeeze-->Boss LS2 (Digitech bass synth wah--> big muff--> phase 90) back to LS2--> sansamp--> amp. POwer to everything but the Sansamp is from a 1-spot.

    Quite puzzled and decidedly annoyed, since I really like the phase 90 and it's always done sterling service up to now..... :mad:
     
  2. Unchain

    Unchain I've seen footage.

    Jun 20, 2005
    Tucson, AZ
    Have you checked the battery/power supply?
     
  3. The Lurker

    The Lurker

    Aug 16, 2002
    Ankh-Morpork
    Yeah, I've tried it with and without batteries, and with/without external power, and got the same result. Both jacks look to be ok.

    I hate to think I fried the thing.... not only would that cost money to fix/replace, but I have no idea how I could have fried it. :bawl:
     
  4. bassman314

    bassman314 I seem to be a verb, an evolutionary process... Gold Supporting Member

    Mar 13, 2005
    Bay Area, CA
    I agree 100%... Simple, effective, lush... Ilove it..

    One thing you might check... Pull the knob off, and remove the cones (thin nuts) on the switch and the pot... remove the jack knobs. Take th ebottom off and pull the PCB Out.

    There's an adjustment pot in there. Now put the jacks together without sticking the PCB back in the case, hook it up to power (use a battery) and your bass and amp... Actually stick it back in your signal chain completely.. and see if adjusting that will make things better.

    If that fixes it, put the pedal back togther, and you are good to go.. if not, inspect the PCB for broken solders, wires, etc. If there are any, deal with it as your own comfort level dictates.
     
  5. The Lurker

    The Lurker

    Aug 16, 2002
    Ankh-Morpork
    Ok, I followed your instructions here..... didn't fix it:( No visible solder or wire problems. Could it be a grounding thing or something?
     
  6. bassman314

    bassman314 I seem to be a verb, an evolutionary process... Gold Supporting Member

    Mar 13, 2005
    Bay Area, CA
    That might be it, but usually a grounding issue shorts the pedal to ground, so you get no sound.. or crackly intermittent sound. If part of the pedal that isn't supposed to go to ground was doing so, it would have functioned just fine when you removed it from the casing.

    The other options are a solder is cracked, and you just can't see it, due to where the crack is, or one of the IC's has gone or is going kaputz... if that's the case, likely it's time for a replacement :(

    How old is the pedal?

    If you need a replacement, eBay is a good source. I got one for nearly new for about $45 or so.. I think that's how much it was..
     
  7. The Lurker

    The Lurker

    Aug 16, 2002
    Ankh-Morpork
    That's the rotten part-- the thing's barely ten months old! :mad: I bought it new in shrink wrap at Guitar Center last December... I emailed Dunlop's tech support to see if they have any recommendations.

    Was really weird, because it developed the problem quite suddenly.... so maybe it is one of the IC's going, or something that cracked....except I can't think of any shocks, bangs, wallops, or anything else it may have suffered....
     
  8. Basstyra

    Basstyra Commercial User

    Apr 3, 2005
    France
    CTO @ Two notes Audio Engineering
    You could post pictures of both sides of the PCB, maybe we could see something.

    And if you don't manag to fix it, I can offer you a fair price for it, as I think I could fix it (or not, but anyway... trying to repair pedals is something I love... :smug: )
     
  9. The Lurker

    The Lurker

    Aug 16, 2002
    Ankh-Morpork
    thanks mate, I'll give that a whirl when I get the camera out..... Heck, maybe I will send it to ya after all!