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Signature Trident MTA rack mounted 4 band graphic eq

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  • Signature Trident MTA rack mounted 4 band graphic eq

    Hi

    This one has come to me with a group of studio stuff and is the last one that need repair
    The reported fault was no 48v phantom . Found a few blown caps that had been changed before. Changed them and tested 48v up to 60v.

    When i checked everything out i can see that loads of stuff been changed before
    18v +/- regs had been swapped for 15v +/-
    I also found 2 short zeners diodes and a cap in wrong way round
    Click image for larger version

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    I have no schematic for this unit.

    who ever has changed these parts has swapped IC9 which has the supply for the 48v
    They have fitted a KA7815. and tried to mod the circuit
    The switch on the front panel turns on a transistor that grounds the centre pin for whatever was in IC9

    When i fit a test reg in the same place as IC9 whatever i fit ie 12v - 15v works perfectly
    when i switch on the phantom is whatever the reg is supposed to be

    does anyone have any ideas on what ic9 should be
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