[sdiy] Korg Polysix Sub Oscillator Problem

[Chris Manders]

Hi Folks

I have gone back to my Polysix restoration project
after a short break.

It may interest people to know that I received this
Polysix in pieces - Someone had literally stripped the
Synth completely apart and taken everything to pieces
- The only thing that wasn't separated was the ICs in
the sockets, although some were missing.
The CPU board had the usual battery leak damage, and I
would assume that this is the reason why the synth was
given to me (probably not working) and in this state.

Anyway, after much repairs the synth is now
essentially together and working, apart from two
things.
I had to get two replacement SSM2044 filter chips, so
the filter settings on the sound board need setting
correctly - Also the Suboscillators don't work, which
is what I am now looking at.

The circuitry for the subtone generation looks simple
- Each oscillator looks to have a 4027 Dual Flip Flop
which is used to generate the sub tone, and each is
controlled by two lines going to the control switch on
the panel.

The sub oscillator switch right now does nothing - At
no point do any of the six voices generate the sub
tone. I am thinking this could be a simple loose
connector, or maybe the Sub Osc switch is faulty, but
I thought I'd throw this open in case anyone else has
come across a Polysix with no sub oscillator.

>From initial view, the synth does not appear to have
any loose or broken contacts. The switch looks fine
too, although I have yet to meter it.

Thanks
Chris


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com