Vintage Synth Repair

I replaced the encoder of an EMu XL-1. I believe that it is the same type. I used a surplus hospital-grade encoder with three pins. It must have been a different mode/type of encoder because it took me four clicks to get the change that I had with one click on the original encoder data wheel. The type/mode that I installed was a 'gray code' encoder as opposed to a binary encoder. The replacement was heavy plastic and metal and originally cost about $25. I mounted it on the rack ears. I used three wires from its pins to the holes on the PCB that the original encoder came out of. Original EMu encoder data wheels appear to be impossible to get, which is strange for a part that breaks easily on a synth that sold for $800 only ten years ago. Whah'sup EMu?

Anyway the new encoder did work, abet four clicks to one. Encoders usually have three pins: Data one, Data zero, and ground. The data lines are always either +5v or zero(ground). They are digital logic. The pattern of these pins compared to the previous pattern on these pins before the encoder was turned one click determines whether it was turned left or right. In Gray code only one bit can change at a time. Binary coded encoders can have both bits change on a click.

I suspect that any cheap three-pin binary encoder would work as an EMu Morpheus data wheel. [The other knobs are potentiometers.] Try and find one that will match the shaft to the original knob and that [maybe] can be mounted into the space of the original encoder.

DigiKey.com seems to have a good selection.

Alan Probandt Portland, Oregon USA (1000 kilometers north of San Francisco)