Pro Audio: Kawai SX240

[boardjunkie]

I recently picked one of these up and have an issue to resolve. It is
a digitally controlled analog polysynth a'la Prophet V, Memorymoog,
etc. The beef with it is apparently connected to the portamento (keybd
glide) in some way. What it is doing is triggering 2 notes at once
occasionally when the glide is on (the second keyed note and the one
it slurred up/down from) in mono mode. Here's the kicker.....if I move
the pitchbend pot slightly either way the extra note stops. Turning
off the portamento stops any erratic behavior altogether. In poly mode
it will just miss a note sometimes....hit the same key and the note is
there. Doesn't seem near as bad in poly.

Seems to me it is a digital issue if something digital will influence
the bizarro behavior. Maybe a a/d or d/a convertor on the way out? I
need to get a service manual for it so I can see just how they're
doing things.

Anyone worked on this beastie before?

Thanks,
Travis

 

[Jerry G.]

Your fastest solution would be to call the manufacture. I have not worked
on your type of instrument, but I would check the power supply performance
very closely, especially for noise on the DC outs, and for proper voltages.

There is also a possibility that there is something clocking off phase or
off frequency somewhere in the processing or the controller sections. Since
the unit is functioning, there is not too great a chance of having any
EPROM, or RAM corruption. But, anything can be possible.

As for any proper recommendations, you should get directly in touch with the
manufacture or their authorized rep. You may have to send them the unit for
proper diagnostics and service in the end.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
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I recently picked one of these up and have an issue to resolve. It is
a digitally controlled analog polysynth a'la Prophet V, Memorymoog,
etc. The beef with it is apparently connected to the portamento (keybd
glide) in some way. What it is doing is triggering 2 notes at once
occasionally when the glide is on (the second keyed note and the one
it slurred up/down from) in mono mode. Here's the kicker.....if I move
the pitchbend pot slightly either way the extra note stops. Turning
off the portamento stops any erratic behavior altogether. In poly mode
it will just miss a note sometimes....hit the same key and the note is
there. Doesn't seem near as bad in poly.

Seems to me it is a digital issue if something digital will influence
the bizarro behavior. Maybe a a/d or d/a convertor on the way out? I
need to get a service manual for it so I can see just how they're
doing things.

Anyone worked on this beastie before?

Thanks,
Travis

 

[boardjunkie]

The mfgr would probably not even know this exists or know much about
it if they did. It was designed by another company (long since out of
business I believe)for Kawai 20 yrs ago. I was just looking to see if
anyone had possibly seen this problem before to point me in the right
direction before I go hunting for it. The pwr supply regulates
properly with no ripple. Its full of ribbon cables and header
connectors but I have already cleaned/reseated all of them and
verified each line with a meter. TIme to get the service manual and
dig in.

Thanks,
Travis