A very old friend, my Sharp combination microwave, convection oven and
grill lost functionality last night. Currently the grill heats as
usual, the fan blows and the turntable rotates but neither the
convection oven nor the microwave produce any heat.

When working do they share the same heat source?

I looked at some YouTube videos showing an "easily fixable" fuse
problem but these videos are about simpler machines.

I changed the turntable drive motor a couple of months ago with quite
pricey spares, so I feel quite committed to keeping this model going.
If they do share the same heat source I'd be more encouraged to delve.
--

Mike