[sdiy] Kenton TB-303 sockets schematic?

Richie Burnett rburnett at richieburnett.co.uk
Mon Apr 10 21:37:26 CEST 2023

The TB-303 that I got second-hand many years ago has a set of 3.5mm jack 
sockets along the back of the enclosure marked SLIDE, ACCENT, FILTER, GATE 
and CV.  I believe these are a mod for use with a Kenton MIDI-to-CV 

Does anyone know the details of how these sockets connect into the rest of 
the TB-303 schematic?  Last time I had the 303 open to replace the tact 
switches I noticed that there were various resistors and transistors inside 
bits of heat-shrink tubing soldered to the copper side of the PCB.  I'm 
trying to find a schematic of the connections for a couple of reasons:

1. I want to know how to fix them if a wire should fall off at some time in 
the future.
2. I'd like to make a judgement on whether these mods affect the sound in 
any way compared to a standard production TB-303, even when nothing is 
connected to the jack sockets.

Before anyone says "open it up and trace out what wires go where", I had 
thought of that!  I'm not being lazy, I'm just trying to minimise the number 
of times I open up the unit as the old plastic enclosure and PCBs are quite 
fragile.  There's also the risk of human error if I trace out the 
connections vs working from a schematic if one exists somewhere?

Has anyone ever fitted one of these kits?  It looks like Kenton Electronics 
still do them...


...but the PDF docs at the bottom of that page don't tell you how to install 
the kit.


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