Hi and welcome

Many owners don't realize what their Synthi or VCS3 is really able to. Aging affects performance, and the rarity makes comparing with a unit in good working condition difficult.
Pointless rumors like "A Synthi can't play in tune", "It's a wonderful noise and effects box but not an instrument" or so don't help.
This is not true. A properly calibrated good working Synthi or VCS3 tracks on more than 5 octaves and is one of the most musical and harmonic synths ever.
Also, it's infinite possibilities can be extended to more infinite possibilities thanks to some great modifications. Unlike the common implementation with extra switches, I'm able to do it without any damage and in a 100% reversible way to preserve the instrument's original condition, appearance and value. This makes it an incredibly powerful machine, with unequaled features for such a compact synth.

Only a very few techs are able to service EMS gear. I saw many units with faults preventing the instrument from working properly, despite/because these were "serviced" by techs - including some famous and renowned ones - who obviously don't know how a Synthi should work.
Many customers were just amazed when discovering their Synthi after I serviced it "Wow, I never even imagined that my Synthi could sound that good !".
Yours can too.

I have taken care of the following EMS instruments.

VCS3 MK1 "The Putney" & MK2
Synthi A MK1 & MK2
Synthi AKS
Synthi 100
Synthi E
Synthi Sequencer 256
Universal Sequencer

Pitch to Voltage Converter
Dual Random Voltage Generator
8 Octave Filter Bank
16x16 Matrixing Panel

I stock rare Synthi components (PA234 / GEL234F1, MFC6070, TAB101, ME9002, selected 74150 or other TTL for the KS...), Jones, Plessey or Bulgin connectors, Cliff K1 knobs, Shinohara meters.
I can build any special cable (umbilical, mains, CV/gate, pin-jack, modules "facilities"...).

I'm also experienced in servicing vintage synthesizers (i.a. Moog MiniMoog D, Moog Prodigy, Korg MS10, Korg MS20, Oberheim SEM, Roland Juno 106, Buchla Music Easel etc...) and other analog devices such as tape echoes, sequencers, effects.

I build and customize great modular synthesizers modules such as Buchla 208 clones or MU format modules.

Feel free to contact me. (My Synthis are NOT for sale, and I'm NOT a synth dealer, so please don't ask if I know one for sale. But if you have EMS gear for sale, I might be interested. Thank you.)

Constantin Papageorgiadis - Belgium
Je parle franšais.
Ik spreek Nederlands.

Available now : modification kits for VCS3 and Synthi A / AKS,
assembled and easy to install yourself.

RVG / S&H push-pulls : a Simple Random Voltage Generator or a Sample & Hold.

Trapezoid polarity control push-pull : controls the trapezoid output polarity.

Sustained/transient gate push-pull : transforms any external gate signal into a short trigger.

Inverter pins PCB  : 2 pins are wired to an inverter circuit and can be used to invert the signal polarity.