Our KHMC107EWH-0 seems to be losing microwave power. It takes longer to cook and warm things, The convection part works fine. Is there any repair that makes sense on this unit, built in Oct 2001?

your issue sounds like low output from the magnetron, if this is the case replacement of the magnetron is the only solution, Here's a link for magnetrons on Amazon to give you an idea of the expense involved:
Amazon co uk magnetron microwave
you may decide to replace the microwave instead of repairing.

magnetrons work only when the unit is cooking
it smells like an insulation from overheating wire so could be a fuse and failing transformer
take it in for a proper diagnosis and quote but if it is over 2 years old the cost to repair could be more than a replacement unit

If autocook is not working and everything else it, there is an issue with the sensor in the oven that detects the steam, The emission of steam is what triggers that unit to shut off. If it wont cook on any settings then the issue is with the microwave generator not putting out enough power. This could be from a lot of things.

I would suspect you have a failed cook relay on the control circuit board, but that can be economically repaired.

Details are here, along with a disassembly video.

see the next steps , use the VOM and fix it. God bless you

1. Check the power diodeThis electronic component is responsible for transmitting current in one direction. If the diode becomes defective it will cause your microwave to not heat. Test the diode and replace it if necessary.
   
2. High voltage capacitorResponsible for storing electricity, this part is a key component in any microwave. Remove, discharge, and test the capacitor to determine if it requires replacement.
   
3. Damaged magnetronResponsible for generating waves and producing heat. When your microwave is no longer heating properly, replacement will be required.
   
4. Thermal CutoffsExamine the thermal cutoffs on both the magnetron and the oven itself. Take off one of the leads and using a volt-ohm meter on RX1, check the terminals. If you get a result other than zero, replace the thermal cutoffs.
   

The clock must be set before you can use the microwave. When you plug it in, it should read all zeros. Enter the time, and press "Clock Set." Time is in 12-hour format. There is no daylight saving time.

For basic microwave use:
1. Press "Power."
2. Press the keypad corresponding to the desired amount of power, e.g., "High," or "Defrost." (The numbers on the keypad have little words on them, like "Warm," "Med," and "High".)
3. Press "Time."
4. Enter the desired cooking time, e.g., "1-0-0" will be 1 minute; you could also do "6-0" for 60 seconds. You can do as little as 1 second, up to 99 hours 59 minutes. "1-0-0-0" would be 10 minutes. "2-0-1-2" would be 20 minutes 12 seconds.
5. Press "Start."

NEVER operate the microwave when it is empty. Put at least a glass of water in it. Never put a glass in it empty; make sure the glass has something in it, like water. Be careful when taking out a glass of water that's been heated; the water has been known, in rare instances, to "explode" and severely scald people.

It is okay to use the approved metal rack (it's coated with ceramic to prevent arcing) when using the microwave in microwave mode. Of course, the metal rack is also fine for use in the convection/combination mode.

"Defrost" cycles between microwave and nothing, microwave and nothing, microwave and nothing. You can hear the cycles. If defrost takes too long, try "Low." Try to avoid using "High," as it kills most nutrients in the food. Opt for "Medium" for slightly longer time; it'll be more evenly heated and healthier. Some things, like popcorn, require "high" power.

To stop the microwave in the middle of cooking, simply open the door. (There's no such thing as microwaves escaping the oven and bouncing around the kitchen and zapping you. I have a microwave tester, and the moment you open the door, all microwaves dissipate; the reading at the door is "Zero" once it's opened.) Or, press "Cancel." If you open the door, you may test the food, and if it needs further cooking, you may close the door and press "Start," and it will resume where it left off. If you're all done, just press "Cancel."

There is no way to disable the 5 beeps at the end of the cycle. If the baby is sleeping and you don't want to hear the beeps, simply open the door right before the beeps when the countdown is at zero. Pressing "Cancel" will give you one beep.

If you have the Combination feature, that cycles between microwave and convection heat, giving the best of both worlds (cooking inside with microwaves and outside with convection), for things such as a whole meats.

To use Combination:
1. Press "Combination."
2. Consult the chart on the microwave (below the keypad) and choose a number from 1 to 4, depending on what type of food you're preparing (i.e., lamb, pork, etc.).
3. Press "Time."
4. Enter the desired time, using the method described above.
5. Press "Start."

The Convection feature simply blows hot air across the food, at the temperature and duration that you set. It's a great way to toast slices of bread for the whole family at once, or bake a pizza.

To use the Convection feature:
1. Press "Convection."
2. Choose the temperature (the degrees are printed on the keypad, such as "350 degrees."
3. Press "Time."
4. Enter the length of cook time, using the method described above.
5. Press "Start."

Be sure to cover foods (with a paper towel or suitable plastic cover) that are prone to splattering. Don't let foods explode and get up into the motor. Clean the inside regularly with a soft sponge and mild detergent, NOT harsh or abrasive chemicals like Comet. Then rinse the soap off with a clean sponge.

Be sure to close the door firmly before cooking, but don't slam it. Slamming it will wear out the latching part, but being too gentle in closing the door may cause the safety switch to not engage, and the microwave won't work (it'll count down and the light will turn on but the motor won't run).

Note: the Convection feature uses more wattage than the microwave counterpart. The volts and amps are listed in the door jamb; multiply them together and you get total watts (although the actual amount will vary depending on your "power" settings).

Hi,
Here is a tip that will help you to figure out what is wrong with yourMicrowave Oven....

Basic Microwave Oven TroubleshootingTips

heatman101 ???

There are a couple of safety thermostats in the oven to shut down power if something overheats. One is on the magnetron tube (the microwave source), the other is on the cooking cavity. These sometimes go bad. There's also a power line fuse that may have failed, or become loose in its mounting clips. These can be tested with an ohmmeter; they should all measure very close to zero ohms if they're good.

Another possibility is that the control circuit board in the oven may have failed. I have worked on several Sharp ovens where the power transformer for the board has gone bad for no good reason. If the board goes bad the oven may appear to be dead as well.

Microwave servicing is best left to professionals. If you're thinking of keeping this one, take it to a service shop (or call for home service) and get an estimate. Then decide whether to repair or replace.

Hope this has helped a little. Thanks for using Fixya!

I can adjust the power level so that circuitry seems to be ok. The longer water boil time could be partially due to the colder winter temperature of the inlet water. We'll just cook the food a bit longer as long as the magnetron is still working.

is your power setting up allthe way (10) is it a convection oven also? microwaves dont usualy have a temp. setting unless there is a probe pluged in inside oven to a jack on inside wall of microwave microwaves can also get old and lose power if so you can get cheep ones at wallmart