Dave Brown is awesome, check this out:
http://modularsynthesis.com/moog/moog.htm
What a fantastic post ! Well photographed and laid out, one can see you put a lot of effort into this and believe me it IS very much appreciated by a modular fan like me. Great info too…thanks for your time and the work you put in to this. I only wish I had this years ago.
Superb!!!
Yes, thank you for the link, John ! Great hi-res photos !
My pleasure, I knew folks here would appreciate it! 
And, just to be clear I’m not Dave Brown or the owner of the Moog, I just appreciate both!
Ok John thought it was your work but nevertheless still a brilliant post. Any more info from Dave Brown …links etc ? First PIC of rear of CP3 Ive seen.
Dave is a really talented and nice guy. I’ve seen him at local synth meets. There is a ton of great information on his site: http://modularsynthesis.com/ He hangs out on Muff’s forum quite a bit, typically in the 5U, DIY and general modular sections - http://www.muffwiggler.com/forum/
When I started on this Moog I needed to figure out which mods were user installed and which were factory installed. I started looking for some photos and found there were really none of the modules themselves and few of the rear of the cabinet. I decided to take this opportunity to take and post photos. I also updated some of the schematic errors as I found them. It was a fun project and nice to get a hands-on experience but did take some time.
Dave Brown
http://modularsynthesis.com/
Welcome to the Moog forum, Dave! Love your work, and if you see anymore rarities in your travels, feele free to post them here! 
Thanks and welcome to the forum Dave!
Those photos you posted of the Moog 984 helped me out quite a bit. Was trying to make a smaller two channel version (aka 982) of the quad matrix mixer. I only had low-rez blurry photos of the actual circuit board. Was able to figure out the “correct” Moog component layout from your 984 photos. So thanks much!
The dots in the drawing are the T-28 Vector pins (.062 holes), black lines the buss wire and colored flying wires. Using the same Vector Plugbord as used in all R.A.Moog early revision modules. Bob Moog called these “Hot Rod” boards as changes and experimentation was easy on that type construction. Just about every R.A.Moog module started out on Vectorbord and some modules never made it to the large production copper etched boards.
Really like this old school construction. Here are a few I am working on.
The module on the left will be the two channel 982 mixer, right module a 902A Band Pass Filter Adaptor. And center top is a ring modulator/mixer/dual reversable attenuator. Had to first do the hardware and metal fabrication. Needed to learn how to drill and tap those Plexiglass standoffs. Wiring and component placement next. Have to get busy wiring/soldering now! 
I also took photos of a Sonic Six that I restored. I posted it somewhere in the forum but darned if I can find it now. That page is at http://modularsynthesis.com/moog/sonic_six/sonic_six.htm
Nice looking DIY, CZ!
Thanks for noticing John!
I started to try and make a Moog module clone after that 902A module appeared on Ebay. The 902A was a real mystery module, the “Band Pass Filter Adaptor”. After investigating further all the info was out there, just had to dig deep to find it. Apparently this was the first R.A.Moog filter module, described by one user as just a guitar type wah-wah with a set of switchable fixed capacitors forming a filter. The original “First Moog” on display seems to have a version of this. Never noticed before but there is a “expo/linear” switch and “gain” on that filter, same controls as found on the 902 VCA. The 902A worked in conjunction with a 902 VCA to form this filter.
There was enough info in the photos posted to try and clone this module.
Still have to wire it up, but fabricating the module frames was a big part of doing it right.
Tried the 70’s method of using plexiglass for the insulated standoff for the rear. Worked with plexiglass before, and knew to drill you need a bit without a sharp edge or it will crack. But found out you have to drill really slow, or it will melt and bind to the bit. Had to learn this new technique. Tapping to 4-40 was just as much fun. Tapped one standoff and was on the last hole when I broke the tap. Forgot, have to do it sloooow. Any heat will melt it in.
The aluminum frames are handmade. Had to saw out the edge card opening.
Then file smooth.
Turned out OK?
I’ll post more pics and info when I get these up and running.
Another interesting photo Dave posted was those CP panel circuits. Dave posted a nice pic of the back of the CP6 routing module. This had the reversable attenuator and 1% 100K node resistors that went to the 904A/B filter pair. There is not much room to mount behind these panels. The photo shows two seperate small boards, one for the resistors and the other for the reversable attenuator. Nice to see the reversable attenuator board was mounted way over behind the one of the multi/trunk jacks. This is where I was going to mount mine for clearance reasons. My IP did not have that attenuator since the filter was in a seperate cabinet. I have since moved the filter and wanted to add the switches and attenuator.
The method of mounting R.A.Moog small CP circuits is a small aluminum L bracket. Moog would also use that Vector Plugbord for many of these early circuits. I was able to fabricate the brackets from some .065" aluminum.
Mounted to a pot here.
And another pic of the brackets and circuit.
Thanks to Dave’s photo’s, I see I was not that far from stock mounting my one board behind the multi jack. Really helped me out.
Any plans for building your own System 55, CZ? 
Just needed to fill a few empty spaces in my Moog. The ring modulator and output mixer seemed like nice additions.
Sorry couldn’t help with the ribbon material. Remember someone auctioning off an original roll some years back. Thought it was made by 3M and no longer produced? Did try to find any part number info I might have saved, but came up empty. It was only the sticky tape top covering. Still needed the conductive material to adhere to.
Makes sense. 
I have linear membrane potentiometers…basically pre-made ribbon controllers. All I needed was the tape for appearances/protection. I ended up going with a brown fiberglass/mylar tape backed with silicone adhesive. I do so hope it works. 
Great pics, info and DIYing, CZ!
Quick update to the photos I posted of the blank modules.
Now that I have all the hardware sorted out, I began wiring up the 982 two channel mixer.
Those Vector Plugbords use .062 pins, type T-28. There is a special insertion tool to help push them in without bending them up. So first I needed to insert about 130 or so pins in the pattern I had drawn out on paper.
Once the pins are in place, the parts can be soldered in. Those pins have a “V” where the component leads go, and have serrated edges to hold the part in. There is also a through hole on the side for wires. Can see why Bob Moog refered to these as “Hot Rod” boards as making changes or rewiring is very easy to do.
First few components. Resistor with leads before soldering in.
Since this was a clone, I used the exact layout of the bigger 984 mixer with the same parts. All 1/2 watt carbon resistors, Mullard “Tropical Fish” caps and the 2N2926 transistors.
All the components for one mixer strip. The 984 had four of these, my 982 will have two.
After the components are all soldered in, the back of the board needs to be wired up. This would be the equivalent of wiring the copper traces on a standard PC board. The bottom of the Vector pins have a large through hole for making the connections between the various components.
Here is the start of the wiring. The component layout is set up to minimize flying wires and mostly use buss wire.
During construction I print out a flipped image of my drawing, so the back side connections appear as I would wire them.
Finished wiring with a minimal ammount of flying jumpers. (green=ground,red=positive supply voltage,blue= negative supply voltage)
Due to panel space I used a smaller type pot used in ARP 2500’s. Went with small 1/8" shaft Clarostat pots. High quality units with stainless steel shafts. Just did not have room for the R.A.Moog typical AB type J pots. Had to fit 10 pots on a single 1U panel with four 1/4" jacks/sockets. Each strip has four 25K linear pots and one 5K linear.
Fitting in the first strip in the frame for testing. Can see those smaller pots.
Time to test this out. Just used jumpers to the pots. Want to make sure the pots were wired in the right order. The volume pots are easy but those tone controls could go either way, and sure enough my first guess was backward. Just flipped the connections and made note on a diagram for wiring to pots.
Ready to test!
So…what does it sound like?
One word, WOW! This mixer is awesome. Very responsive tone controls. Mixes great and can get that soft to hard clipping/overdrive. Feeding back into itself I was able to come up with some interesting tones. Although this is not voltage controlled, a 902 VCA and 911 EG in the feedback path yielded some great contoured filtered tones. Almost like the Minimoog feedback patch, but with tone boost/cut controls to shape the overdrive. With two channels, many patch configurations are possible. From just a final stereo output mixer, to a mono mixer with a send/return. Or a feedback overdrive/distortion with asymmetrical clipping.
Really like these original Bob Moog designs and circuits. Many of the earlier systems had these various final output mixers. Perhaps thought as needed as these were AC coupled mixers and would block out any damaging DC from going to the recording unit and monitors. Bob even made a 981 four channel, single output mixer. (no tone controls.) Noticed one of these on the early Carlos system from the SOB days. A few other 981’s on the Max Brand system. Still have not seen a close up of the original 982 mixer, but guessing there was only four pots per strip and used a single panpot to mix between the two inputs.
Have to get busy and finish the other strip, now I know it all works and sounds awesome!
Love the idea to use jumper clips to test things out before soldering…
Stephen
.
Great job! Can we expect a “CZ Synths” or “Rider Modular” company in the near future?
I’m sure that is how many started out. Finding those parts used in the old Moog is quite fun and there are great deals out there, you just have to find them. For instance, they still make those Vector T-28 pins today. They are a bit different with ROHS and are phosphor-bronze. The price for anything Vector is expensive, about $11 for 100 pins and around $70 for a thousand. In my search at a radio ham fest/flea market, I found a box of what looked like junk with 1100 of those pins scattered about inside. Paid $5 for the lot. One of my best scores at those. Another E-bayer had a 1000 pin bag and the insertion tool for around $14. Just have to know what and where to look. But is is getting more and more difficult to find those exact parts, even though there are many out there. So it is limiting to a small scale personal production.
If I was going to make any kind of Moog modules for sale, I would try to do it all on SMT boards with discrete components. Just recently saw the same idea with the Moog filter set in Eurorack. It is really do-able with some minor substitution of parts. But all of those early Bob Moog designs are made with discrete parts. That mixer I just did could have been done on SMT with different low noise transistors. The only difference is I would not try to change the modules to work with modern voltages. +12/-6 rails, S-triggers, and those low level signals that sometimes need to be amplified. And no IC’s of any kind. All part of the way those work and interact with each other. Would be really cool to see a minature set of 900 series R.A.Moog modules in a small Euro format. I’m really surprised no one has done it yet. Could be a small market for those if done right.
Seems like every clone out there changes resistors to handle today’s typical gates and voltage signals. Some of the Moog modules amplify by a factor of 2, like the 902 VCA and each input on the CP type mixers. All that clipping and distortions from the small offsets and amplifing and inverting those asymmetrical signals is part of the sound and function. Not going to work the same if the signals are already too hot. Too many engenieers that know better try to “fix” these. I would leave the design alone, it is perfect for what it is. Just make them smaller.
EDIT:
Almost done the 982 Two channel mixer.
