Microwave not heating: Should I pay a contractor to diagnose?

Replacing is NOT a good option for some models–Repairs are NOT that hard.
hate to offer this advice, since I ‘ve heard of quite a few DIY that have been killed attempting this, since the world power is, or can be still stored in the capacitor of the microwave, and KILL you dead, WHEN unplugged ! still, you can DIY or find a supporter that can easily do this .
OTOH, I ‘ve got two very nice KitchenAid microwaves. I replaced the plain one that was installed over the oven, with a convection/microwave, ( cost > $ 550 ). finally after 14 years, they BOTH “ break ” — no heat, but everything else worked finely .
There is no possible effective way to replace these microwaves cheaply, since there is trim work that just is n’t going to match properly or easily. then for me, the best choice was to learn how to do it SAFELY and cheaply. My cost for replacing both magnetrons was less than $ 80 total. It took about an hour each, plus a few hours learning and a few hours properly sourcing the part. note that I am already an “ about ” a real electrical and electronics tech/engineer. I will walk through what I did :

Troubleshooting:
If it wo n’t heat water at all, but everything else is working ticket, then proceed .
Safety:
Before you take it apart, KNOW that ANY of the expose wire can KILL you. Treat it all like a affluent gunman. If charged, it has 5,000 high current volts available to do you in. After unplug, FIND the uncover capacitor. You will need to ensure that the leads have been shorted together and besides shorted to grind to the chassis. I ‘ve seen others use insulate screwdrivers to do this, which are probably very well. I built my own resistor net that both would discharge a 5,000 volt capacitor, but do it slowly, and would not arc over the resistors that were not natively rated for > 5000v. Do NOT “ check ” the live voltage, unless you have a eminent electric potential probe made for tube TVs, rated over 20,000 volts. now, make or get a permanent wire to short that capacitor while working on it .
Check the components:
Transformer
I checked the transformer with an ohm meter, on all the leads, and besides checked it to grind. ( I do n’t remember if ANY of the leads are supposed to be grounded, but if not, make certain it is infinite.. ) besides look for anything that might look burned or loosen connections and repair if necessary. If the DOOR is broken, specially mechanically, do NOT try to replace ! ! If this leaks, it can slowly kill you — microwaves are very nasty, if let out of that box .
Diode
With an ohm meter, verify that it works — conducts in one direction merely .
Capacitor
You should be able to use the ohm meter to first base start charging the capacitor, and then reverse the leads, and charge it in turn back.

Magnetron
There are two wires that go to a heat element inside, designed to use 2-3v. That element is most surely burned out, but you should be able to check it, ( and check on the new substitute you barely bought. ) bill that neither of my bankrupt magnetrons showed ANY problem, and yet silent did NOT work ! The element showed it was not broken or grounded .
Buying a replacement magnetron
You can buy the “ official ” KitchenAid for about $ 150- $ 200 if you are stupid, or buy the claim lapp part elsewhere. These are difficult and expensive to make, so there are actually only a few models, and they are all private labeled and multiplied by 5x cost as a net income .
The magnetrons are not the lapp for Panasonic and likely others. GE, Amana and likely about 30 others are all going to use the “ lapp ” magnetron. The alone differences will be how they mount, which is important. Notice which management the chief leads in the center come down from the magnetron, which will either follow, or oppose the exposed fins. This 90 degree mount determines MOST of the model, and possibly if the bolts come mounted on the frame or not. VERIFY YOUR region by looking up your model # microwave. But, the photos should match. You can buy these from Amazon, Ebay, or other forte parts appliance sites for $ 35 – $ 45 DELIVERED. When you buy, you might besides buy and replace the light bulb .
Unscrew the old, and screw on the new magnetron TIGHTLY, so the microwaves do n’t leak out. Connect all the leads up. Plug it in with a cup of urine, and examination it. ( IF you have a human body lockout switch, with obviously wo n’t work until you reconnect it ).

Reassembly
now for the DANGEROUS part …. Remember that remainder charge ? ? First unplug it, and ASSUME that all those wires are hot. You can either discharge that capacitor again, or find a manner to stay aside from then with the case. The circuit is SUPPOSED to self-discharge to safety, but YMMV sol do n’t find it. once that it is reassembled, retest it before re-mounting it .
That ‘s it …. Leave me a gloss if you ‘d like me to post some links for sourcing the magnetron later .

BONUS
After replacing, do NOT toss those magnetrons. They are not named that way for nothing. Pry the event apart so you can remove the fins and the tube. You will find two HUGE POWERFUL magnets. Remove the fins, and then cautiously remove the magnets. If you ‘ve saved the box it was shipped it, or a larger one with foam, STORE your magnets carefully, so isolated energy does n’t destroy other things. Be more careful that you think you need to be, since they can break fingers and pinch painfully. I have the four I removed, and can use them to pick up nails from roofing or re-find anything ferric in the yard .