I have this Sanyo microwave oven which produces no heat. Controls all
work; fan works, etc. No fuses blown (that I can find).

What can I check, please?

It's model EM-G471EUK, microwave and grill.


It could be the magnetron, which is the device that emits the radio waves used
to cook the food, or more precisely, excite water particles causing those
particles to create heat from movement friction within the food (no bull!)

You may want to consider your options. You may not be able to source
replacement parts for your microwave, especially a critical part like a
magnetron. Replacing the oven with a new one may be a better way to go. If
the problem was with something like the mains interlock switches, then it would
be feasible to replace the switches and continue using the oven as the switches
are more than likely industry standard parts that can be obtained at a local
appliance repair shop, even with ovens of today.

That's what I did with my old 1981 Panasonic Dimension3 oven when the interlock
switches wore out. I replaced the mains interlock switches on both the top and
bottom door latch holders as well as replacing the plugs on the wiring harness
that connected to the switches as they had burned from heat caused by
resistance in the bad switches.

The safety warnings cannot be overemphasized as microwave ovens are one of the
most hazardous electronic pieces to work on. Improper service can cause
exposure to hazardous levels of microwave frequency radiation. Another hazard
is the mains capacitor, which is capable of storing a charge that is lethal.
Even if the capacitor is configured to self-discharge (a resistor connected
between the leads of the capacitor is a typical configuration), you must always
assume the capacitor is live until you discharge it to a proper ground. -
Reinhart