Maxim MDS-500

[Peter Snow]

Hi all,
This week-end I purchased an old Maxim MDS-500 analog drum machine at the local used
musical equipment store for a decent price.
5 channels, trigger inputs, usual controls for noise, tone sweep, click, tone freq etc,
etc. It's similar to Tama units or even the Simmons SDS8 in functionality. I've never
heard of Maxim before but the guy in the store says he thinks they were made by/for Pearl.

Actually, it has quite a few neat features: 5 separate audio outs for each channel in
addition to stereo output with full EQ on left and right channels; each drum can be
continuously panned left or right; switched factory preset or user control; 3 XLR and 1/4"
outputs for the left, right and mix channel; output effects loop for the master mix.
  
Now the problem is that one of the channels does not produce a tone - noise and click work
OK though, so I suspected a bad tone generator chip or perhaps a VCA. But when I opened it
up, I find it is full of SSM2044 chips.  Aren't these VC low pass filters?  There are no
filter functions on this unit so what are these chips being used for? Surely they are not
being driven into oscillation to use as VCOs? If so, seems like big overkill when
something simpler could have been used, like a 566...
Anyone have a clue on this?  Or even better, a schematic?  I searched with Google and
found nothing.
Thanks,
Peter