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Korg PA 600, fully JACKCON capped, power issues

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    Korg PA 600, fully JACKCON capped, power issues

    Hey guys, got a Korg PA 600 in for repair. Apparently when the lady brought it in, it did not power on. I plugged it in and behold, it powered on.

    Opened it up and found a few broken wires, but they were to controls, not to anything power related, and when said wires were disconnected the unit functioned just fine.

    Unsure as to what is wrong, but it sometimes takes quite a while to boot up, other times it's very quick to boot.

    This is an odd one for me, never encountered this before.

    They keyboard is only about 2 years old, and all the caps test fine.

    The 4700uF one I posted is reading 5200uF on the meter, so no problems there. Its a JACKCON LHK series, which is a shit series and cap for how much this thing is new, rated 2000 hours.

    There are also a lot of SMD caps, but then there's a couple LNP non polar caps in the audio output for the speakers section of the board. Those are rated for 1000-2000 hours.

    It's kinda sad to see such an expensive item made with such cheap components.

    But I digress, I'd like to have some insight as to what the problem might be.

    The power supply they used isn't the worst, it's a UNIFIVE 15v 4a power supply. You can find them at unifive.com. They actually have good safety listing on their site, and board views for their open frame supplies.

    Anyone have any ideas?
    Last edited by jazzie366; 03-04-2017, 09:39 PM.
    Popcorn.

    #2
    Re: Korg PA 600, fully JACKCON capped, power issues

    Fixed it!

    Power supply was not being very nice to us, in the end I opened it up and there were no bad caps, and it still held voltage. But it had excessive noise on the output.
    Not sure why, but replacing the "UNIFIVE" power supply with a SinPro medical grade one made it work like a charm again.

    It's kinda weird though, UF power supplies are made pretty well, there was two input common mode chokes and two x capacitors, 120uF 400V primary and two 680uF 25V secondaries. All CapXon branded, but they all tested well within spec.
    Popcorn.

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      #3
      Re: Korg PA 600, fully JACKCON capped, power issues

      Sometimes caps check ok on esr, but will short under load...Thus giving you noise on output, clearly not filtering... Just a theory in your case...

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