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Crate PA8FX

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  • Crate PA8FX

    I have one of these crate PA8FX units that 2 resisters are burned on the mixer / input section.
    R32 and R34, I'm guessing they are 10 ohm but not sure.
    Everything seems to work fine except the line input (J5) is distorted.
    probably a bad 4558 as well.
    This unit is a rush job and I'm not going to be able to get a schematic from Crate /SLM till Monday. so if someone has a schematic and can verify the resisters, that would be great.
    Thanks

  • #2
    R32 and R34 list as 10 ohms.

    Make sure clamp diodes D5,D6 are not shorted. They protect J5 and P6 (EFF/AUX In LEVEL)
    Attached Files
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      Thanks.
      Thanks for the schematics too!
      That fixed it up. Diodes were good.
      Did have another problem though. the PA output was distorted. severe crosover noise that was coming and going.
      turned out that the bias pot is bad.
      would go from 3mv to 20mv then 100mv just touching it. got to swing by and get a replacment in the morning.
      I'm guessing 10mv across the .33ohm resisters should be about right for the bias.
      Sound is good and no visible crosover distortion at 1khz.

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