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Faulty motherboard

Discussion in 'Troubleshooting and Repair' started by shirreff, Apr 7, 2012.

  1. shirreff

    shirreff

    12
    0
    Apr 7, 2012
    I have a number of 1980's music keyboards all Korg M1's.
    I also have quite a few spares mostly motherboards for the M1.
    The problem I have on one board is that it just hisses like a radio that is not tuned in instead of playing the keyboard sounds.
    Another motherboard I have just does not produce any sound.
    I have tried the boards in more than one keyboard and swapped all the other internal boards over so I am confident that I have narrowed it down to the motherboards.
    On the one that hisses I have swapped a couple of capacitors and one transistor but it was purely guess work and it made no difference.
    The board that produces no sound I have not touched.
    Any ideas?
     
  2. davenn

    davenn Moderator

    13,288
    1,756
    Sep 5, 2009
    hi Shirreff
    Just wanted to welcome you and at least let you know you werent being totally ignored :)

    the lack of responses from anyone would indicate, that like me, we couldnt offer any specific help. I have seen a Korg synth many many years ago. Never ever worked on one.

    without circuits for the boards, and photo's to help visualise what they look like we would be just stabbing in the dark.
    Do you have any circuit info? done a search for a service manual ?

    Do the boards have any markings as to test points TP's etc where and what voltages you should expect ? You firstly need to confirm that you have the correct voltages coming out of the power supply section(s) before anything else

    cheers
    Dave
     
  3. shirreff

    shirreff

    12
    0
    Apr 7, 2012
    Hi
    Thanks for the reply, I can sort out some images and I have the service manual.
    I am pretty sure the power supply is ok as I have 3 power supplies and they all produce the same result.
    I will sort out some images tomorrow along with the service manual thank you.
     
  4. shirreff

    shirreff

    12
    0
    Apr 7, 2012
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