Vintage Simmons Drums (UK) Users Group

Double checked the schematics... The 3086's are drawn as full schematics and 
not standard IC's, that's why I missed them. Sure looks like the same setup.
If anyone tech-skilled want to look at the SDS-III schematics I'm having 
suspicious thoughts of the 1458 in the top right corner on the schematics. 
Pin 1 gives just 1/10 of the value on the corresponding channel. As I 
interpret the circuitry this directly affects the tone/noise pot (which is 
fully functional BTW).

What does the LFO section offer then? Doesn't look that impressive on the 
schematics. Time to mod the SDS-IV maybe? Trying to read pictures 
online+schematics getting this;

LFO speed (slow->fast)
range: slow/fast
LFO shape: square/sine
LFO on/off
run time (short->long)
run on/off
output level

So the SDS-III has no waveform control. interesting, I didn't know this...

electronically yours, jesper
- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

Order your own copy of the Machinepop/Imiafan
split-EP at www.electronic-obsession.se/label.asp

"Varf\ufffdr har du s\ufffd m\ufffdnga pianon?" (Nora Persson, 9 \ufffdr)

----- Original Message ----- 
From: <michael.buchner@...>
To: <Simmons_Drums@yahoogroups.com>
Sent: Monday, April 02, 2007 3:49 PM
Subject: Re: [Simmons Drums] SDS-III vs SDS-IV internally


Hi Jesper,
this is exactly the thing I want to know. The III is the four channel 
device, as far as I know and the IV the two channel device, but the IV is 
not only half III. The IV has no master section with run generator and lfo, 
but may be the single channel is also different to the III.
I repaired Wolfgangs III two month ago. It has no oscillators at all, the 
tone is nothing but a resonating ladder filter, copied 1:1 from good old bob 
moog. If you turn the Noise/Tone pot to noise, the resonance is completely 
off, so also the impact click will not be audible. But on my schematics of 
the III there are 3 3086 per channel, these are containing transistor arrays 
to build this filter.
What I am wondering about is this pot on the IV called "Waveshape". Is this 
an osc or only an lfo? Maybe a good photo of both solder side and parts side 
would help.
Michael
  ----- Original Message ----- 
  From: jesper@...
  To: Simmons_Drums@yahoogroups.com
  Sent: Monday, April 02, 2007 3:01 PM
  Subject: [Simmons Drums] SDS-III vs SDS-IV internally


  Hi List!

  I'm looking inside my newly arrived SDS-IV due to a dead oscillator and 
I'm
  comparing it to the schematics of SDS-III. Is it just me or aren't they
  alike? There are no 3086's on the SDS-III schematics but quite a few in 
the
  SDS-IV...

  Anyone with a SDS-IV schematic around?

  electronically yours, jesper
  - -- --- ---- ----- ---- --- -- -
  www.electronic-obsession.se

  Order your own copy of the Machinepop/Imiafan
  split-EP at www.electronic-obsession.se/label.asp

  "Varf\ufffdr har du s\ufffd m\ufffdnga pianon?" (Nora Persson, 9 \ufffdr)





[Non-text portions of this message have been removed]




Yahoo! Groups Links