Here’s the way I mod a Mini for external CV and Gate in.
Please note that I stock new edge connector pins and use them when performing this mod.
Extend keyboard CV from brown/white wire normally going to edge card pin 9A on board 2, to n/c switch on CV input jack.
Connect tip of CV input jack to a piece of wire.
The other end affix a new edge connector pin.
Insert into pin 9A of board 2.
Extend keyboard GATE from white/orange wire normally going to edge card pin 6A on board 2, to n/c switch on GATE input jack
Connect tip of GATE input jack to a piece of wire.
The other end affix a new edge connector pin.
Insert into both pin 6A and 20B of board 2 (or insert just to 6A and jumper R65 (pin 6A) to anode of CR10 (pin 20B))
Remove or snip the wire from the keyboard connector #5 (usually green) to the farthest (n/c) bussbar.
Replace R1 (590 ohm 1%) on board 2 with 50 ohm cermet multiturn trimmer and 576 ohm 1% resistor (50ppm or less) in series.
After Mini has warmed up and power supply calibrated, adjust keyboard to exactly 1v oct output using this trimmer.
(alternatively, you can use a 620 ohm fixed resistor for R1 with a 25K cermet trim across it.)
The keyboard will now be at exactly 1v/oct output.
Tune VCOs last.
Now the VCOs will be exactly at 1v/oct for external CVs also.
This mod cuts out the keyboard’s CV and Gate and inserts your own.
The external CV then passes through the Mini’s glide and is available on the orange filter keyboard tracking switches.
Also, Minis are in the key of F, where 1 volt in produces an F.
Most other synths are at C, where 1 volt produces a C note.
I’m not including the mod to automatically transpose the Mini from F to C, but otherwise this is how I will often mod them.
I also tend to replace all the summer resistors on the VCO board with newly matched precision resistors and often the same treatment is applied to the octave switch’s matched resistors.
This increases their tracking and octave setting accuracies.
Some Minis used a dark blue style of 1% resistors that don’t hold their values well over the year. The brown colored 1% resistors they often used tend to do better and remain more accurate.
The brown carbon resistors they used on the older Minis can be really off value by the way. I’ve measured some that were up to 40% off.
When found in the power supply section on older Minis, I tend to replace them with metal film 1% (50ppm drift.)
A voltage controlled synth is only as accurate as the voltages being provided.
Btw, I’m not a big fan of the Lords of the Minis site.
Much incorrect info and other good info I provided that wasn’t credited.
When I see pics of Minis billed as “restored” still with 30+ year old caps in it, I tend to laugh. Minis weren’t made with 30 year old caps.
Polishing the wood isn’t restoration.
They even have me listed in their links as “Minimoog parts”, even though I’m at well over 400 Minis serviced or restored - probably more than all of LOTM authors put together. 