I have a Yamaha Electric Guitar - AES 800, the guitar technician needs a wiring diagram as the tone controls are not working but it is not the pots as they have been replaced. Where do i get a wiring diagram?

Unable to find a diagram, however, makesure the pots were replaced with identical units as not only does the resistance have to match, but the taper of the resistance MUST match the original ones. There is a letter designator on the pots as part of the part number and this MUST be the same on the replacement.

There is very little to go wrong other than the pots and the capacitors and the switch and of course the pickups.

The AES-820 control system has a user manual at the Yamaha website and that one does NOT have a "tone" control, but instead has controls for the two pickup mix. This is not reaally a tone control as is commonly thought of, but changes the sound in a different way. Not sure if your unit has the 820 system, as that system has two mix pots, a rotary selector, and another switch.