The latest stuff done

Bonotron - effect unit

A nice effect unit!

It was made by Bonotron, a company that still seems to be active in Karlskoga, Sweden.

Modifications on Doepfer A-110 VCO

Doepfer has a lot of nice synthesizer modules, and they often gives away the schematics. This leads to a lot of modification being made to enhance and enrich the already nice modules.

The A-110 VCO is easy to modify to get softsync and FM-input for a more complete function as a voltage controlled oscillator. The schematic is found here. The electronic part is really easy.

How to mount the extra jacks and switches

To make life simple, I did a small template for the drilling of the extra holes. It is very nice when all the holes are made equal on all VCO´s when making the modification on more than one module.The drilling itself was done by my dear wife, who is a silversmith and good at making nice holes in metal.


Here is the SVG-file. It contains one layer with the scanned panel and one layer with the drill guide. The SVG-file can be opened by Inkscape and adjusted. 


A nice picture of the A-110 after modification.


Fix dead buttons on a Roland MC-303

Long time ago, my main sequencer for musical excursions were the Roland MC-303. Maybe not the best in the world but sure did function well enough to have a lot of fun with. So, when a unit appeared for sale on the second hand market, I bought it.

To my great disapointment, the Swedish Postal Service ("Posten") did it´s worst to kill the unit. But instead of going to the complaints department I ripped it open to find the fault.

What was dead? Some very important buttons were completely unresponsive. The green circles shows which ones.


The schematic clearly showed were to look if you consider which buttons that were dead. The wiring shows a normal way of scanning a lot of buttons using som logic.


And what did I find? A small crack on the PCB, just behind the "TAP"-button. It cut the PCB traces as shown above in the schematic.


And the fix (quick and dirty). The MC-303 now works perfectly.