[sdiy] Kenton TB-303 sockets schematic?

Roman Sowa modular at go2.pl
Tue Apr 11 12:51:15 CEST 2023

Based on what I could see in Kenton's page photo this is very minimal 
kit, with maybe 3 resistors and a transistor. CV for pitch and filter 
are probably just resistors going to summing nodes of VCO and VCF 
respectively, probably directly to the base of 2SC1583, so without any 
voltage at their sockets, there's no difference from un-modded TB303. 
The other 3 are just on/off switching signals.

All I'm saying is, the kit does not change anything when nothing is 
connected and is so simple that has no chance of ever needing a repair.


W dniu 2023-04-10 o 21:37, Richie Burnett pisze:
> 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 
> interface?
> 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...
> https://kentonuk.com/product/roland-tb-303/
> ...but the PDF docs at the bottom of that page don't tell you how to 
> install the kit.
> -Richie,
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