CMT101SGW0 Whirlpool Microwave - Instructions

My microwave began suddenly making a loud harsh humming noise while cooking food. I did not let it go on long enough to know if it cooked the food or not. I did some Internet research and learned that it was likely the Magnetron. The test for this was to run the microwave for at least a minute on the lowest power setting and see if the noise cycled on and off. It did, so I (actually, my wife) ordered the part from partselect.com using the model number. I was successful in replacing the part, and we are back to microwave popcorn and quick defrost for a price that was less than a service call, however, it was time consuming, required a large work area, and access to 5 out of 6 sides of the unit. So proceed at your own discretion

Caution:

The first thing in every set of repair instructions was to discharge (short-circuit) the capacitor, as it may store large (as in lethal) amounts of electricity even when it is not connected to a power source. I had never done this, but found these instructions:

“Discharging your microwave's capacitor is absolutely essential in preventing injury to your microwave, your tools, and yourself. A capacitor stores a large amount of electricity even when your microwave is unplugged, and it must be discharged before beginning any repair.
A capacitor is discharged by creating a short circuit between each of the two capacitor terminals, and between each terminal and the chassis. The chassis is the metal mounting (bare metal surface) of the capacitor. Read these directions thoroughly before you proceed.
With your microwave unit unplugged, touch the blade of a well insulated screwdriver to one terminal. Gently slide the screwdriver forward until it reaches the other terminal, holding it there for a few seconds. Be aware that this often results in a loud and startling 'POP'.
Repeat this procedure in order to create a short circuit between each capacitor terminal and the chassis (bare metal mounting plate surface). This same method can be applied to a capacitor having three, and not two, terminals.”
I had not run my microwave in over a week, and then while my part was shipping, left my microwave 'unplugged' for more than two days, and my capacitor apparently discharged itself, although I did go through the above procedure carefully and completely - just in case.
Step-By-Step:
1. You must remove your microwave from the cabinets - it is impossible to repair otherwise. This is best accomplished with 2 strong people - my wife and I made it work, but wished for another guy.
a. While supporting the microwave, remove the two screws coming down through the cabinet above.
b. Lift the rear of the microwave as much as possible, then tilt the front down - there is a clip high on the left side, as well as the hinge/clips on the bottom.
c. If you do not lift it off the wall all at once, you may have to lift the rear even farther to remove it from the hinge/clips on the bottom.
Important Note: Always beware of the microwave door, if it is bent or broken and cannot retain a seal, the microwave not function as a safety feature to keep from releasing microwaves.
2. Remove the vent cover on the top/front of the microwave - be careful, it's plastic.
3. Remove the vent cover and light panel on the bottom of the microwave - this is several screws and some simple wire clips.
4. Remove the "shell" (top and sides) of the microwave - this is several more screws on the back. Make sure to remove the plate that is holding the cord in place on the top.
5. Remove the interface panel by the screws on the top (which had been hidden by the vent cover) - the wires can remain attached, just slide it aside.
6. Remove the metal cover on the right side at the rear; this will expose the Magnetron and the Capacitor. Remember to immediately test and discharge the capacitor!

7. After you discharge the capacitor, remove the other cover plate and the support bracket - in case you haven't noticed, this is a time and space consuming operation.

8. You

Unless you have a very comfortable background with electronics and electricity, I don't necessarily recommend taking apart a microwave. If you are very handy and are going to be VERY cautious to follow the rules of discharging caps and testing voltages before moving forward, then go for it. That said, I took the microwave off and apart. Not knowing where to find the parts, I was fortunate that the installer put the instruction book for the microwave inside the front vent slot above the touchpad for reference. it details the location of every part and it tells you very clearly what each part you test should show specific to this microwave on your multimeter. Find this guide online if you don't have it. Turn on the microwave for 20 seconds with a glass of water to make sure it's not heating - that with the noise means it's eeither the magnetron, cap, or diode. Read the notes on this site for all of the basic things to look for with the magnetron, diode, and capacitor. Once comfortable with the guide, locations of those devices, and how to test, then take it down and apart. Unfortunately, I didn't do all those things in that order, and it only wasted a lot of time trying to find the parts. Once I found the parts and put all the screws and covers back for all the areas that didn't need to be accessed for the repair, testing went quickly. The diode was bad. Ordered a new one and had it in 3 days or so. That means your microwave will be apart and sitting somewhere for a little while until you get the part and have time to repair it. Putting the diode back isn't too bad. Reassemble the microwave and put it back up again. If i had to do it again, it would take me 20 to 30 minutes once the microwave was down and on a table. Also, I used some bricks with towels over them or you could use some sawhorses to keep the microwave elevated so you can plug it in and run it after installing the new component. Again, make sure you discharge the cap before touching anything again even if you didn't run it, but just plugged it in.

I turn off the income electricity by shutting down the corresponding circuit breaker. Then, I removed the control panel from the microwave which gave me access to the capacitor and adjacent diode. After that i unscrewed the defective diode and replaced it with the new one and BINGO!

Read some instructions and easily found the fuse. Replaced it. Still didn't work. Took control panel off to check door switches. Nothing I read mentioned a second fuse. Tested and it to had blown. Ordered another one. Popped them in. Done.

I looked up a YouTube video of someone with a similar over the oven microwave. That helped me get into the area behind the control panel where the door switches are. I checked the springs and the cam rocker? The thing that actually hits the button on the switch when the door closes. They were in good condition so I assumed the door switch was bad. There are two so I just purchased one figuring (hoping) that only one was bad. And lo and behold only one was bad. Bing bam boom. Put it all back together and I'm set. Not too difficult. Took a week of work because it takes like 50 days to ship. My kitchen looked like a hurricane after image because of all the parts scattered everywhere.

Instead of telling you, i have question do you have any instructions on how to do the repair. It would have helped save time on the repair.

This job took longer then it should have, becasue I did not start right in the begining. I did figure it out quickly after the wrong start.

You were a big help in picking the right part to correct the problem. You should be able to help with the repair. Thank You

I used a Google search to show how to access the area behind the front panel. There was a folded paper copy with a schematic and wiring diagram in that space.Then I used a multi-meter to determine which of the THREE micro-switches was causing the problem. I called your help line and ordered a replacement switch. The switch was delayed in transit so your agent credited me with the cost of shipping.

When the part arrived, it had three terminals instead of two as shown in the on-line picture but that did not cause any difficulty in using it. It took about 20 minutes to remove and replace the old switch.

All seems to be working well now.

Finding which of the THREE switches was the problem was the most difficult part of the repair. All three "clicked" but the defective one did not click as easily. It needed to be depressed more than the door latch can would provide. Old age?

Take off top facing over microwave using screwdriver also protection plate for diode and capaitor. Disconnect diode from frame, bracket to capacitor then remove, disconnect wires leaving diode on capacitor for right connection, replace, rewire done.

Removed the microwave from above the oven by loosening the two screws above the microwave. As the unit tilted outward lifted up and the whole unit came out all the time feeding the power cord through the cutout for the power cord. After it was out removed the cover and identified the capacitor and made sure it was discharged and removed and replaced the diode. tested before reinstalling and it heated up just fine. Reversed order and reinstalled . Very easy job maybe a second hand to help fish the power cord when installing and removing.

Remove “over the stove” unit. Remove unit shell case. Unscrew and disconnect diode. Replace diode. Re-assemble. Put unit back in place.

Don't waste your time with other parts stores online. Partselect sells quality parts and they arrived 2 days early. I purchase a door switch from another online store and the switch was defective.

PartSelect website indicated replacing the high voltage power supply diode is the solution for "no heat" 99% of the time, but the diode was OK. There is more info at the website concerning the case of "loud buzzing and no heat" indicating the magnetron needs to be replaced. As an electrical engineer with knowledge of microwave components, this was also my best guess. However, getting to the magnetron is not the easiest job, but it's not impossible. You also have to be careful to bleed off any charge stored on the high voltage power supply capacitor. Luckily, I found my KitchenAid service manual tucked away inside the unit since I couldn't find it online.

Remove the two screws to the plastic vent strip at the top of the unit. That exposes a metal cover (upper right) held in place by two more screws. (Found that removing the screw holding the key panel in place and moving that out of the way made for more work room) Remove the metal cover. The HV diode (visible) on one end is secured to the chassis by a screw. The other end is fitted to the HV capacitor. So unscrew one end and pull the HV diode off the capacitor. The replacement fits on like the old one came off. Very simple repair. But it would be safe to short the capacitor terminals to the chassis first. Noticed that it appeared the sparking was caused by the HV diode's outer casing being worn by the asbestos covered wire next to it and laying against it. I made sure the two were not touching, before putting the covers back on. Also, the problem started with an occasional spark when the MW started. It quickly deteriorated to a full, non-stop electrical sparking. You can hear it, smell it, and see it through the top vent. You don't need to remove unit to work on it.

Loosened but did not remove screws that held up microwave over range,removed grill on top by loosening screws that held grill in place.removed small mesh grill on right side of microwave, this gave me access to capacitor ,diode is connected from one lead of capacitor to a metal plate ground,Disccarged capacitor to ground by shorting terminals to ground using a thick insulated screwdriver.Since the diode was screwed to the top of the metal plate I cut it out with a pair of side cutters .I then connected the new diode to the capacitor with my long nose pliers and groonded the other end to a more accessible part of the metal grounding plate.I then replaced all parts in reverse order.Works like a charm.

Whirlpool Model# MH1150XMS-0 purchased in 2004. I called Whirlpool and they suggested a new microwave. No big surprise - being the thrifty person that I am I wasn’t taking this for an answer. I figured if I had to purchase a new microwave what was $35.22 (part# PS373828 + shipping) if it worked.

I replaced the latch on the microwave door. Once the latch was replaced. I also took this time to make sure that the microwave door was in alignment. Thereafter, I had to adjust the door interlock switch behind the microwave console panel to recognize the microwave being closed. Yes, gaining access to all these areas was a bit difficult but have patience. TADA!!!....microwave is working. #girlsrock