Yamaha EL90 Factory Reset

[Paradox]

Just wondering if there is a factory reset for Yamaha EL90 organ.
Thanks
Ian

[Hammond-Organist]

When I had my EL90 I used to pop in the Yamaha black top floppy disc, not sure if this is what you are after. Don't know if there is a menu method to completely clear the instrument.

[alandlees]

I'm not sure if it will achieve what you need but you can hold down the top left data control button under the screen whilst switching the organ on. This will clear all the pistons back to factory.

There is also a self check mode achieved by holding a C sharp chord on the lowest position on the lower manual whilst switching on the organ

[Paradox]

Thank-you. I am just in a learning curve, and was wondering which settings belong to a memorised registration, or bulk data, which ones are persistent or lost after switching on and off, and which may have been reset by powering on with the top left data control button.
I was aware of the self-check mode. The chord is the second octave of the lower keyboard though ?