Below is a link to a service bulletin detailing a multi-step procedure for checking out the systems in a Yamaha DX7II. You press “yes” after each step to advance to the next one. The problem is that each step has to be completed before the display reads “ok” or “ng,” and you can press “yes.”
Since I don’t have a breath controller, I can’t access other things like the MIDI test. Does anyone know if it’s possible to skip steps with this procedure?