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Mesa Dual Rectifier 3-Ch Solo wth LF oscillation from 5U4GB's (SS Mode)

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  • #16
    I just had a Dual Rectifier Solo with similar sounding oscillation when using the FX loop, FX Master up, send full up, SS rectifier mode Raise the channel master to kick it off and once established I was able to turn the channel master down to zero and it would carry on at around 12Hz, so narrowing it down quite a bit. Decoupling caps checked out OK for ESR.

    Adding capacitance to nodes B (change 30uF to 100uF) and C (added 47uF in parallel with 30uf) of the power supply effected a cure.

    Click image for larger version

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    So, if you ever see DR that again...
    Experience is something you get, just after you really needed it.

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    • #17
      Originally posted by nickb View Post
      I just had a Dual Rectifier Solo with similar sounding oscillation when using the FX loop, FX Master up, send full up, SS rectifier mode Raise the channel master to kick it off and once established I was able to turn the channel master down to zero and it would carry on at around 12Hz, so narrowing it down quite a bit. Decoupling caps checked out OK for ESR.

      Adding capacitance to nodes B (change 30uF to 100uF) and C (added 47uF in parallel with 30uf) of the power supply effected a cure.

      [ATTACH=CONFIG]53421[/ATTACH]

      So, if you ever see DR that again...
      Excellent news, nickb! I gotta give this a try. We have four Dual Rectifier & four Triple Rectifier Solo heads in our inventory, most are already flagged for preventative maintenance work. I'll report back when I get to that project.
      Logic is an organized way of going wrong with confidence

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