Vintage Simmons Drums (UK) Users Group

Thanks for a short and good description!

I'll start by changing the 1458 then, will buy a bunch today... It might 
have been imagination, but maybe there was some sound of the oscillating 
transistorladder. It always feels good to hear that I've interpreted 
something right. It's not easy for a guy who just opens the machines if 
something is broken and gives up if he doesn't draw a conclusion the first 
two hours. ;)

None of my local electronics dealers have the 3086. I wonder where I got the 
spares I do have last time...

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 9:56 PM
Subject: Re: [Simmons Drums] SDS-III vs SDS-IV internally


The SDS III has no tone generator. If you want to produce tone, you drive 
the (original moog...) filter into self oscillation by raising the resonance 
to a certain level. To understand the circuitry, call the "pitch" pot 
"cutoff frequency", the "noise tone balance" is "resonance", "impact click" 
is a short additional pulse on the "cutoff frequency".
In the schematics the 1485 you describe is the filter output amp. CV in is 
at T2, all CV's are added there. The filters input is IC4, Pin12, the only 
source of the beast is noise. Feedback is supplied by connecting the output 
via the noise/tone control and R56 back to the CV input.
Michael
From: jesper@...
  To: Simmons_Drums@yahoogroups.com
  Sent: Monday, April 02, 2007 4:20 PM
  Subject: Re: [Simmons Drums] SDS-III vs SDS-IV internally


  So there _are_ 3086's... I didn't see those on the schematics. I'll gladly
  take a few pictures when I dig into it again. I bet it's the same then...

  But do you say that the 3086's are the tone generators so to speak? From 
my
  limited experience and todays values I have my suspicion set at a 1458 
which
  in connected to both waveform and noise/tone potentiometer.

  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)

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