Vintage Simmons Drums (UK) Users Group

A few years ago I had a distortion problem with an SDS1000, and
I came up with a useful trick for checking the system out.

I bought a 28 pin IC socket - same size as a Simmons EPROM
and connected 8 wires from address line A0 to data line O0,
from A1 to O1 throught to A7 to O7.  Eg, pin 10 to pin 11, 
pin 9 to pin 12 etc.  The wires just push into the socket.  

You can get a 2764 EPROM pinout here.

http://pdf1.alldatasheet.com/datasheet-pdf/view/117107/NSC/NMC2764-2.html

As the SDS1 counts through the EPROM, it counts up the data
and you get a staircase sawtooth wave sound out.  Look at the
SDS1 output on some sort of wave editor or audio oscilloscope
software on your PC and look for a smooth regular sawtooth
wave with 256 steps.  If you get big or uneven steps, you've
got a faulty SDS1.  (My SDS1000 turned out to have a faulty
DAC.)


Steve