Vintage Simmons Drums (UK) Users Group

> The chips that are missing are marked iC37 & IC38. Can anyone verify 
> that these are curtis chips & what the curtis part number is ? 

They're Curtis CEM3394s.  There should be one for each tom.  Does one of the
toms work?  There is also a CEM3372, but that's a filter for the snare.  
CEM3394s are not easy to find.  Paul "MOTM" Schreiber keeps most Curtis chips, 
but he's out of 3394s.  You should be able to get the data sheet off his site 
though.

Do you know why the 3394s were removed?  Before you replace them, check the 
power supply.  Curtis chips are very vulnerable to excess voltage.  The
PSU should give +15v, +5v and -6.5v.  I had a PSU go bad in an SDS1000
(cut down SDS9 in a rack), and it took out the Curtis chips and a random
selection of other devices.  Sound familiar?

I have schematics, but my scanner is dying.  If you're not too far away, I
might consider photocopying and posting them for you...


Steve