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vout
Joined: Oct 06, 2007 Posts: 35 Location: scotland
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Posted: Sun Oct 28, 2012 12:01 pm Post subject:
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Hi Moogah,
That would be awesome if you could do that, I'm sure there would be a lot of interest in a pcb.
Cheers, vout |
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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
Audio files: 11
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Posted: Sun Oct 28, 2012 5:00 pm Post subject:
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Quote: | I captured the schematic in eagle a while ago (the first time this thread went dead). If nobody else is still working on this I'd be glad to do a layout and get a prototype made and see if I have better luck! |
sounds like a plan .
I was going to give it a go at one point but have no time for the forseeable future, so yes please . _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any |
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Moogah
Joined: Dec 26, 2007 Posts: 26 Location: USA
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Posted: Wed Oct 31, 2012 11:10 am Post subject:
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OK, I'll give it my best shot. It seems that there may be a few errors on the schematic that will need to be resolved, but after working on the MB808 and a half dozen other drum synths I've got a pretty good idea of how this circuit is *supposed* to work.. hopefully that will help.
I'm currently finishing the last couple hours of work on a SEM VCF PCB which will be sent off for a prototype within the week. While I wait for that I'll start getting this project moving and will post more info then! |
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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jmejia
Joined: Mar 12, 2009 Posts: 114 Location: portland
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Posted: Tue Nov 13, 2012 10:28 pm Post subject:
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We (my partner and I) have a prototype pcb I'm stuffing right now. (Finally)
I don't expect it to work as it's directly what I inherited from Fonik.
I also have heard rumours that the factory schematic has errors. If anyone has info on that I would love any clues. I've tried contacting several people who have made various webposts about it to no avail.
That said - this pcb is plenty roomy for troubleshooting so we'll do our best to figure things out.
Moogah by all means give it a shot! Maybe between all of us we can figure this thing out. I've never heard an SDS3 in person, and they absolutely never show up on ebay. I'd love to get this project off the ground! |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Wed Nov 14, 2012 1:40 am Post subject:
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jmejia wrote: | I also have heard rumours that the factory schematic has errors. If anyone has info on that I would love any clues. I've tried contacting several people who have made various webposts about it to no avail. |
IIRC i pointed out at least two errors when i handed over the PCB? i am not sure, though.
all i remember today is that there was an issue with the decay potentiometer.
and one has to keep in mind that the schematic as it is expects an negative going trigger (again IIRC).
i am sorry that i cannot contribute more here... _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
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Moogah
Joined: Dec 26, 2007 Posts: 26 Location: USA
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Posted: Wed Nov 21, 2012 11:11 am Post subject:
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Just a heads up: The prototype boards for my SEM VCF came in and I'm going to finish that project before doing any serious work with this one, with the holidays coming I don't expect to get back to this until January |
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jmejia
Joined: Mar 12, 2009 Posts: 114 Location: portland
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Posted: Thu Nov 29, 2012 4:15 pm Post subject:
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fonik wrote: | jmejia wrote: | I also have heard rumours that the factory schematic has errors. If anyone has info on that I would love any clues. I've tried contacting several people who have made various webposts about it to no avail. |
IIRC i pointed out at least two errors when i handed over the PCB? i am not sure, though.
all i remember today is that there was an issue with the decay potentiometer.
and one has to keep in mind that the schematic as it is expects an negative going trigger (again IIRC).
i am sorry that i cannot contribute more here... |
Fonik you mentioned there were a couple errors - but weren't able to give me specifics. I think it was already pretty late in the game at that point. I'll take those tips in mind.
The rumours I was speaking to are regarding the factory schematics themselves. Anyway I finally got the rest of the parts today, and will build it up and start testing. This will be slow going so don't anyone get all excited yet. Ha. |
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arnoid
Joined: Aug 23, 2009 Posts: 57 Location: Belgium
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vout
Joined: Oct 06, 2007 Posts: 35 Location: scotland
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Posted: Wed Feb 20, 2013 8:28 pm Post subject:
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Just giving this a bump - having watched an SDS4 (less than half an SDS3) go for £1000 on ebay the other day makes me want a DIY solution even more! |
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arnoid
Joined: Aug 23, 2009 Posts: 57 Location: Belgium
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vout
Joined: Oct 06, 2007 Posts: 35 Location: scotland
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Posted: Thu Feb 21, 2013 5:07 am Post subject:
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Yes, I've seen that article. Michael Buchner is a real expert on Simmons gear, he's been very helpful to me in the past when I had problems with my SDS6 and SDS7. I get the feeling though, that his SDS3 clone is not for public consumption, because of the commercial tie-up with Mode Machines. |
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arnoid
Joined: Aug 23, 2009 Posts: 57 Location: Belgium
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vout
Joined: Oct 06, 2007 Posts: 35 Location: scotland
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Posted: Thu Feb 21, 2013 8:54 am Post subject:
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Thanks - I saw the end of that thread but hadn't read it all. So Michael Buchner did share his design, but ultimately it seems to have been another stalled attempt. I wonder what the real difficulty is with this project, on the face of it the circuit seems quite simple (not that I'm an expert, but compared to some of the projects around here). |
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jmejia
Joined: Mar 12, 2009 Posts: 114 Location: portland
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Posted: Fri Apr 26, 2013 1:54 pm Post subject:
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I'm not sure of the full lineage - it could be that the designs I got from Fonik, are originally from Michael Buchner. But at any rate - xnor and I have a semi-working prototype with some issues that need to be resolved. If anyone wants to help - I can post the schematics here, maybe we can compare - and figure this out. This project is a LONG time in the works - but I'm determined to get it up and running. |
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xnor
Joined: Apr 24, 2013 Posts: 5 Location: Cascadia
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Posted: Fri Apr 26, 2013 2:06 pm Post subject:
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bumping this so I get on this thread.. |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Fri Apr 26, 2013 2:35 pm Post subject:
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What kinds of issues, and what kind of help can I provide? |
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jmejia
Joined: Mar 12, 2009 Posts: 114 Location: portland
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Posted: Fri Apr 26, 2013 3:25 pm Post subject:
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The LFO bleeds/dominates the audio output, there is a fair amount of background noise and ground him, and most of the pots don't do much. Decay seems to work, as do LFO rate and mix, and the basic sound does trigger. First phase is doing careful comparisons with the factory schematic, but while we do that it would be great if someone could comb the original schematic for potential errors as I've heard that it may have some! I guess the LFO section is a good place to start as it functions but doesn't interact with the rest of the circuit correctly. Oh and we did some scope probing at test points around the ar section - that is looking pretty good/correct. |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Fri Apr 26, 2013 7:20 pm Post subject:
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I assume you've read the linked document way back that has the service scoops in it? Definitely sounds like you're outside of that, but it has various test points you can check for things and that seems like it might be helpful on the physical side.
I'm beat tonight, but I'll see if I can find time to look at the schematic / play on a breadboard or simulator soonish. |
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jmejia
Joined: Mar 12, 2009 Posts: 114 Location: portland
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Posted: Fri Apr 26, 2013 8:45 pm Post subject:
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Yep - scoops is on the agenda - my primary concern is that there is something functionally wrong with the factory schematic that could be tough to identify/diagnose. A simulator test could be enlightening if that's the case - thanks for the offer! |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Fri Apr 26, 2013 8:58 pm Post subject:
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I will probably be asking some foolish questions once I start looking because in all honesty I don't know anything about his machine. Right this minute, for example, it sure LOOKS to me like the LFO should be grounded but there's no ground symbol....
Edit: so that is my first question. Is that really connected to ground? (pin 3 of the 1458, and all the other things on that wire? In simulation, it appears to work as an LFO without ground, but the speed setting has no effect (as you might expect, there's no voltage divider there). Only the switching in or out of cap C14 has any effect on the LFO speed.
I do see you said the LFO speed works correctly, so I expect that this is correctly handled, but when troubleshooting it's best to leave no stone unturned, even the really obvious "not the problem" ones.
Edit 2: what's the spec on the drum pad triggers? positive going, negative going ?? |
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THeff
Joined: Sep 01, 2006 Posts: 229 Location: Florida
Audio files: 33
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Posted: Sun Apr 28, 2013 1:06 pm Post subject:
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I perfboarded the SDS-3 circuit several months ago and was able to make all of the sections work. The "Factory" schematic is full of errors and missing components. I did a lot of research about the SDS-3 in order to determine why the circuit does not work when built according to the schematic. The perfboard is pretty ugly and is kind of a "furball" but it did allow me to test everything out.
One of the biggest discoveries that I made was that the filter/osc design is Moog, but indirectly. It is really almost identical to the ARP 4035 module. In fact I found a small story about Dave Simmons and it mentioned that he used an ARP-2600 synth to test his idea and create the prototype.
This info helped a lot because I was able to debug the schematic when compared with the 4035 filter design. The only real difference is that the pins on the CA3086 ICs have been swapped around.
The schematic is so full of errors that I wonder if it is really a "Factory" schematic, or if it is, I wondered if the errors were placed there on purpose to mislead and prevent copying.
Here is a list of errors, corrections, and additions that I made to make everything work:
1.) The biggest error is that pins 2 & 3 of IC3a are swapped. This prevents the filter from operating completely. Pin 2 should connect to the junction of R51 and R53, and Pin 3 should connect to the junction of R50 and R52.
2.) The control voltage to the filter is overdriven and a 3.3K resistor needs to connect from the base of T2 (Junction of R24, R23, R28, and R33) to ground. This effects the total control of the filter and the value may be adjusted as desired.
3.) Capacitor C20 (0.47 uF) should connect to the collector of T13, not the emitter of T9.
4.) The bottom side of the 22k resistor R81 (junction of R86, D9, R87 and R88) should connect to -15V.
5.) The junction of Pins 3 & 6 of IC7 and R73 (LFO) should be connected to ground.
6.) The 22k resistor connected to Pin 5 of IC10 (Run generator) should be 2.2k.
7.) All of the LEDs are connected backwards.
8.) The 470k Decay Time pot should be audio taper.
9.) The 100k Run Time pot (92) should be audio taper.
10.) I modified the circuit to match the noise bleed-through mod in the bottom right of the schematic, but it still would be better with separate noise and Tone level controls I think.
11.) These changes should make everything work, but I'm sure further improvements could be made.
I was going to enter the schematic into Eagle and make a PCB but I have to may other responsibilities right now. My idea was to make a PCB with the LFO and Run Generator included, make four boards and only populate the LFO and Run Gen on one of the boards. This would create a full SDS-3 module.
Regards,
Theff
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Moogah
Joined: Dec 26, 2007 Posts: 26 Location: USA
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Posted: Sun Apr 28, 2013 2:11 pm Post subject:
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Wow! Very cool man, I'd noticed the many errors in the ladder filter and was coincidentally using my layout for the arp4035 as a starting point for this hah.
My SEM filter boards are just now getting into peoples hands and helping people get going on that will be my #1 priority for a little bit, but I could have a prototype layout ready pretty quickly now with the info you've found! |
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xpmtl
Joined: Aug 10, 2007 Posts: 162 Location: Brussels, Belgium
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Posted: Mon Apr 29, 2013 4:01 am Post subject:
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I had Fonik schematic layed out in eagle so I added Tim's corrections to it. I think i didn't omit anything. I'll make a prototype this week (board is already done) and report back.
I've added the bleed thru mod also but i'm not to sure of the R58 (22K). Is the down arrow means it goes where it was previously meant to go or does it connect to -15V ?
If anyone finds errors before I etch, please report back.
X.
EDIT : SEE SCHEMATIC ON PAGE 11 FOR A WORKING CIRCUIT. _________________ http://sdiy.xpmtl.net Last edited by xpmtl on Sat May 18, 2013 6:49 am; edited 2 times in total |
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Moogah
Joined: Dec 26, 2007 Posts: 26 Location: USA
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Posted: Mon Apr 29, 2013 9:19 am Post subject:
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This is fantastic! I'd love to build a few of these in euro format |
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