They will keep schematics very closely controlled for fear of the casual user electrocuting himself as he attempts a repair. There are very high voltages and dangerous radiation lurking in these machines.
I doubt you will ever get diagrams unless you set up a business and apply to Sharp to be an acreddited service channel.
You do not say just why you need a diagram - I doubt that service personnel make much use of them.
Good luck...
Peccavi, December 2009
