A few hours after found the MZ-X500 SM, I also stumble upon this.
I know some of us think this could be dangerous for people who don't know what they are doing (and I agree) , but even I, who have 3 years of electronics engineering education, am not too brave to take apart my own keyboard - maybe I'm just too stingy.
But for people who have a brave and adventurous spirit - I was once upon a time, this file can be very helpful.
Once again, be careful!! The risk is in your own hands.