Microwave not heating

[hpibmx]

Hi everyone,

I’m back to this lovely forum again, so I tried to heat up my food using my microwave after 8 month and realised it’s not heating up at all while it turns on, tried on all options (level of heat) no worked expect the very last I assume is 750W if I’m not mistaken. I can provide pictures next day as well,
And even the very last option wasn’t supper heat at all when I set for 2 min bowl of water. Only the bowl would be heating!

What I’ve done tested thermocouple, capacitor, magnetron, door switches, fuse, and the diode (replaced) they’re reading all good (on continuity) and cap value.

Any idea of this?
Please do let me know if future info needed or pictures, I have been away from this forum for long.
Cheers.

[coppercone2]

lol I have bowls like this too, the colored ceramic ones prevent heat from going into the food, but they get hot

[james_s]

Do you get voltage at the primary of the HV transformer when the unit is cooking? The safest way to test this is to disconnect the wire to the primary and connect it to another load like an incandescent lamp. You might also be able to hear the transformer humming when it comes on. This will tell you if the problem is on the primary or secondary side.

[mayor]

FWIW, resistance test (if that's how you tested) on the magnetron isn't guarantee it's still good. Wasn't in my case.

[james_s]

Yes I've had magnetrons fail more than once such that the filament checked good and nothing was shorted but they did not oscillate. It has been relatively rare though, the most common problems are faulty door interlock switches and cracked solder joints.

[CaptDon]

If the magnetron ever overheated one or both ceramic magnets may have cracked. In that case the magnetron is dead!! How much line current does the unit draw?

[james_s]

If the magnetron ever overheated one or both ceramic magnets may have cracked. In that case the magnetron is dead!! How much line current does the unit draw?

I don't think I've ever seen that happen but I suppose it's possible. I have several magnets from defunct magnatrons on my fridge. I paint them with a thick coat of enamel to prevent them from chipping and they make good strong general purpose magnets.

[TERRA Operative]

Check out this website, it has all the info you need to fix a microwave:

https://www.repairfaq.org/sam/micfaq.htm

[tkamiya]

If the bowl containing water is heating up, obviously, rest of the system is producing RF at least.  So first thing I would try is use different vessel to hold water and see how it performs.  I have a set of PLASTIC bowls that act like this. 

[james_s]

Oh I missed that part, yeah if the bowl is heating then the microwave is working, definitely try a different bowl.