[sdiy] Cat SRM 2

[Tony Allgood]

Hi all,

A little while ago I wrote asking for the schems of this little baby.
While I found the original one and the SRM, but not the SRM2. Surely
there can't be that much difference?? But there is:

The SRM2 features CEM3340s as the two VCOs, one SSM2044 as the VCF, and
a good'ol 3080 as the VCA. The noise gen is a MM5537,
ger-chunk-ger-chink etc. So very different to all that came before it.
The PCB is positively empty, except for...

This one I have, is full of track cuts, extra components on top and
bottom. At first I thought it had been badly bodged by a previous
repairer. But no. These are factory installed changes. This may be a
pre-production run, or very early on in its product life. Or just crap
engineering. Either way, its pretty terrible to work on.

The worse thing about it is that all the 8 pin DILs are fitted together
as pairs in 16 pin DIL sockets. Including the 3080 and the noise gen IC.
So its 'ger-chunk-ger-chink' even when the thing isn't playing. And high
frequency bleed through is awful.

But if anyone has the schems for board C revision B I would be very
grateful. The keyboard scanner is playing silly buggers, by adding
random offsets to VCO1 on power on, and keeping them there. Doh...

And I have tried Voyetra, but they 'don't support that product anymore'.
I mean how hard is it to have all the old schems as PDFs on your
website?

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan