Appliance Repair

Eventually it will break.

This is the rule for household appliances. I would just prefer that it not be a two year old microwave that I had installed into the kitchen cabinetry. Yes, I can probably fix it… after I dismount it and lower it out of place. A task much easier typed than done. No matter, I am on-call this weekend. I will be around the house all day anyway, may as well get something productive done.

An over-the-stove microwave costs a few hundred dollars, too much to just run out and buy a new one. Not enough to justify a repair call. I do not even want to think of what it would cost to get a repairman out to the house. Driving from Kona? Hawaiian rates? I can think of few easier ways to get robbed.

Naked Microwave
Microwaves are pretty easy to work on, just get the cover off and everything is right there
I can fix this. Microwaves are relatively easy. Plus, it is an LG, you can actually buy the parts without going through an authorized extortionist. I have long ago learned not to buy certain brands, restricting appliance purchases to companies for whom you can actually find the manuals and buy the parts.

It takes a while, poking about inside the guts of the microwave to find the trouble. I check the magnetron first, worried that the failure involves the most expensive part in the appliance. Nope, correct resistance across the leads, open circuit to the housing… All good, a bit of a relief.

Melted Switch
This is bad… A badly damaged microwave door switch just as I found it
The microwave would appear to run… Timer, lights and all, it was just that nothing got hot. The next step was to see if any current got to the power transformer for the magnetron. This is also a simple circuit… Power in on the power cord, a filter module, a relay on the control board and through the door switches. Poking around with a meter I find that the circuit is open through the door switches. This is bad… Well actually it is good, these are some of the most easily fixed parts.

The switches just snap into the plastic doorframe. Removing the upper switch I notice a melted housing where one of the wires connects. This is more like it! The switch is toasted, the internals melted, it no longer connects with a nice snap when you press the plunger. Most likely a bad contact that got hot with current flowing. This switch carries the full current of the magnetron, around ten or twelve amps, easily enough to melt it.

As I show my wife the damaged switch she asks how long it will take to order a spare part, obviously wondering how long the kitchen would be torn apart. I look at her… “Order? I probably have this on-hand.” She seemed somewhat doubtful. It takes me less than a minute to retrieve a bin labeled switches from the shelf. A few moments later I hold up an identical switch. Score one more for the parts bins!!

An hour later it is leftover chili burritos with melted cheddar cheese for dinner.

Author: Andrew

An electrical engineer, amateur astronomer, and diver, living and working on the island of Hawaiʻi.

One thought on “Appliance Repair”

  1. So I’m a DIY appliance repair guy too, had the same microwave issue caused by the same problem, a melted door switch. So besides just replacing it, do you have any idea why the switch melted in the first place? I read elsewhere that it might have to do with opening the door while the microwave is running, instead of pressing the stop button, which I am guilty of. Do you think this is what caused it to melt, or is there some other reason?

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