Oscillators synchronization

Osc1's "ramp level" push-pull is on the left, osc2's on the right,
linked with 10K and 33K resistors.
The yellow-heatshrinked white cable goes to R192 on board C.
"EMS Sync is far more tonally versatile than any other analogue synthesizer commercially available." (Graham Hinton)

Graham Hinton explains the mod on this page.
Two versions are possible : variable or fixed sync.
Since the variable one needs to add a pot and drill a hole, I did the fixed one. With my way of doing, only one osc can be slaved to the two others (if a pot is added to do the variable one, it might be a push-pull one, allowing to chose between two slave oscillators, maybe I'll do it one day).
Here's the how to for osc1 as slave, it can be adapted for any oscillator you want.

Pulling the "triangle level" knob will make osc1 slave to the corresponding oscillator. It's also possible to enslave to both osc2 and osc3 together.

Pots to replace with push-pull ones :
- osc2 and osc3 "triangle level"
- osc1 "ramp level" (optional)

This pic of Graham Hinton shows on which leg of R192
(and other resistors) to connect the sync cable.
It can of course be sodered on the other side of the board.
Connect a 33k resistor to the "E" lug of osc 2 'triangle level' and connect the "D" lug to pot top. Do the same for osc3.
Join both resistors together to a cable that will go to R192 (22k resistor, the fifth from the top of osc1 on board C) on the ME9002 transistors side.

Optional : osc1 "ramp level" pot can be replaced by a push-pull to select 2 different resistor values (I used 10K/33K, but you may choose the ones that best suits your needs). This way, 2 sync levels are available. Just connect the "E" lug of the push-pull to the R192's cable and solder the resistors to the "D" & "F" lugs, connect their other legs to the osc2 "triangle level" "B" lug and link it to osc3 "triangle level" "B" lug.

No hole
Push-pull pots
Matrix MKI/MKII layout
Voltage controlled shape and response
Hi/lo range switchable oscillators

Simple Random Voltage Generator and Sample & Hold

Documents, manuals, dopesheets, links

Filter 18/24 db
Filter slew/unslew
Attack and decay time extension
"Synthi 2" interface