The Roland GR-300 synthesizer was released on the early 1980´s and still an unique device for guitar players since then. The original japanese connector used on it is not produced anymore, when I had a chance to buy a GR-300, I decided to make a new connector for the cable I had from my old GM-70 midi converter and use it on the GR-300.
It´s impossible to write this Instructable without mentioning Wayne Jones and his page with lots of information about the GR-300 and many other guitar synthesizers, without his page I coudn´t fix the cable and connector.
Step 1: Preparing the PCB - 1
The first step is to prepare the printed circuit board that will later be populated by the 24 signal pins plus the guide pin. Cut a piece of single sided fiberglass PCB 42mm x 14mm ( I know, I made mine a little short). Use a 0.8 mm drill to make the 24 smaller holes on the PCB and a 1.8mm drill to the guide pin. Follow precisely the dimensions on the attached image to avoid fitting problems later, I used a coordinate table of a mini-mill to do that, fortunately my mill has dimensions in milimeters.