Maxim MDS-500

[Colin Fraser]

----- Original Message -----
From: "Peter Snow" <psnow at magma.ca>
To: "Synth DIY" <synth-diy at node12b53.a2000.nl>
Sent: Monday, January 01, 2001 11:38 PM
Subject: Maxim MDS-500


> 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...

Don't have a schematic or anything, but a 2044 would be a minimal part count
solution for a vco with a pure sine output.
This is even suggested in the datasheet.
If you follow the output pins on the 2044s, you should find they are
buffered by an op-amp.
Hook up a scope to the op-amp outputs and you should see what they are
doing.
If there is no signal connected to the 2044 input, then it is certainly
being used as an oscillator.
The datasheet is at synthtech.

Colin f