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AMEK TAC noise on low EQ pot

Discussion in 'Vintage Analog Gear' started by PhantomBox, Aug 23, 2011.

  1. PhantomBox

    PhantomBox Active Member

    Low EQ frequency makes noise by PhantomBox » Mon Aug 22, 2011 7:11 pm
    Hi everyone.

    On a Scorpion II that I'm servicing, on 2 (out of 32) of the 1001 input modules, the low frequency pot in the EQ has an odd problem: when I turn the pot all the way up there is a sudden increase in output volume on this channel which is reflected by an immense feedback and hum. And when I turn it all the way down the output is almost muted.
    I checked it with the schematics and couldn't find anything apparently wrong.
    Any idea what's going on?

  2. Boswell

    Boswell Moderator Distinguished Member

    Are the two channels with this fault an odd-even pair? I don't know the insides of the Scorpion II, but other Amek boards I have worked on have suffered from leaky coupling capacitors. Can you PM me the schematic of the EQ module?
  3. PhantomBox

    PhantomBox Active Member

    There's also a pair of channels (13+14) whose LED meters are not working. LED meters on channel 1 to 8 are sub group controlled and are doing OK and channel 9 to 16 are directly addressed but those two wont work. When I test with a cable from a working LED meter to one of those 2 they are doing fine so the LED circuit seems to be OK but there is no way to trace the problem back from there without taking half the console apart. TAC did a lousy job on the ribbon cables ...

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