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Crown DC300A Oscillating

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  • Crown DC300A Oscillating

    I have a DC300A on the bench that one channel was folding the top half early into a load. I couldn't get the original 2N5804 driver transistors, so I used a pair of MJ21194 transistors as replacements. I adjusted the bias for that channel, and it has no DC on the output. Now the amp goes into a big oscillation as soon as it clips into a load. I added a 200pf compensation cap as C119, which is shown on the schematic, but that didn't help.

    Do I need to pay big bucks for 2N5804's to make this work correctly?

    Or should I replace all of the output devices with MJ21194's on that channel?

    Or just try compensating caps elsewhere?

    Service Manual

  • #2
    The parts list shows different caps for C107/ 207, depending on the output transistor grade.
    (Crown is big on graded outputs)

    Certainly Not an easy amplifier.

    I would contact Crown.
    They have been most helpful to me in the past.

    Comment


    • #3
      Have you taken notice of this little ditty about C119/ C219?

      DC-300A-C119_ C219.pdf

      "Used Only If Oscillation Occurs During Test"

      Comment


      • #4
        Originally posted by Jazz P Bass View Post
        Have you taken notice of this little ditty about C119/ C219?

        [ATTACH]47186[/ATTACH]

        "Used Only If Oscillation Occurs During Test"
        Yes, I specifically added that cap to stop the oscillation, but it did not help.

        Comment


        • #5
          I replaced the MJ21194's with MJ15024's and that took care of it.

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