Saturday, August 15, 2015

JX10 & MKS70 Display

Published on Aug 15, 2015 Guy Wilkinson

"Here is a video of my latest home project; a replacement display for the Roland JX10 and MKS70 Synthesizers. Note that blinking characters on the display don't blink regularly due to video editing.

To attach a new display to the synth and display the basic text is quite straightforward but getting the best out of a modern VFD module using fancy fonts and graphics is much more complicated when linking it to a 30 year old electronic design.

It all began when Frédéric Vecoven had developed a replacement operating system for these synthesizers and kindly invited me into his project to contribute. Fred had developed an extensive set of software tools to allow full simulations of the synths and VFD displays, making the job a lot easier for me as all code could be developed and tested on a Linux or OSX Platform without real hardware. It meant that it worked almost perfectly when running on real JX10 for the first time.

Fred’s JX10/MKS70 software provides additional data in order to make an elegant design of display layout. Tone edit is particularly well enhanced as is the play mode and function display.

In this demo, the display is powered by the JX10 but could also be powered separately if wanted. Careful design of the new circuit, PCB and routing of power in the JX appears to have removed the 'hum' that you can just about hear in the noise floor of the standard JX. The hum is caused by the refresh scheme in the old VFD display and I expect to demonstrate a lower noise floor in final testing when the first bare PCB arrives next month.

Soon I will release details and there will be a viable solution to replace a failed display!"

Quick note: the video is on the display replacement only. The music is for background purposes only and was not created using the Roland JX-10 or MKS-70.

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