microwave - no power

[Charles Bishop]

About an hour after I last used my microwave, I tried to use it again and there was no power - the display was dark and nothing I could do on the front panel brought it back.

What is the likelihood that it's just a blown fuse, or something similar? If so, how easy would this be to get at and repair? What are the odds that it's deader than the dodo? If it's the microwave generator whatsit, would that mean the display is dark?

It's a Sharp Carousel and is at least 4 years old.

I checked the outlet and no joy there-it has power.

[roger61611]

Could be a fuse...

[Art Todesco]

[Mark Lloyd]

15 years ago I had a microwave that failed like that. I took the cover off, knowing there was almost nothing I could do to fix it. However, what was wrong was one of the few things I could fix. A blown fuse. A replacement was about 69 cents at Radio Shack.

I still use that microwave.

[Beachcomber]

A fuse is likely. It's very typical for them to die of old age. You need an exact replacement though in terms of type and amperage. This fuse is part of the protection circuit that protects not only the microwave oven, but you.

I just had one die (A Sharp 1000 watt model). For about 3 weeks, I could smell something burning when I used the microwave. Then suddenly no power...

The problem is that my fuse melted the fuseholder and the plastic support underneath. It still could be fixed, but at $69.95 for a new replacement oven... the price alone of not having to clean it did it for me.

Fuses also blow when there is trouble with the interlock switches.

Anything that draws high current, such as air conditioners, microwave ovens, etc. can be trouble for fuses.

Beachcomber

[Charles Bishop]

Cool. I looked at the back last night and there were warnings against taking it off beacuse of high voltage. Also, the screws holding it on are star screws - they say it's for my protection since the high voltages are there.

Do micorwaves have any large capicators or capicatorlike that would hold a high voltage if it had been unplugged for a while?

I'm going to at least take the cover off even if I have to junk it so my sone and I can see what's inside one.

What is odd to me is that the last thing I did was to heat something for

11 seconds. I think it beeped at me to let me know it was done, then I opened the door, took out the stuff and closed the door. Unfortunately I didn't notice at the time whether the display was dark or lit. Assuming it was, is it likely the microwave would have failed when it wasn't being used? If not, i may just misremember the beep or what happened when I opened or closed the door.

[Rich256]

Yeah, there is a cap that might give you a pretty good bite. It might be bled off but still a good idea to keep your fingers away. What I do is attach a shorting wire to ground if I am going to be in that area.

I will bet on the fuse too.

Had one that was shorting like mad. Took off the cover and found a moth in the waveguide.

[Charles Bishop]

Is it likely I'll recognize the fuse? A flashing neon sign: "Fuse"? or do I have to look around. The likeliest place I'd think would be just after the line cord comes in.

Did you put it in the daily log with "first instance of actual bug in a microwave"?

[Rich256]

The ones I have seen are the normal Buss type and usually mounted in an open area on the chassis. Usually it is a slow blow or thermal type.

Just did a bit of searching and found some URLs you might take a look at:

Another thought. Not likely problem, but are you certain that the breaker to the oven has not tripped? It could be on a breaker by itself.

I just recalled fixing one of the first Armana ovens. It was one of those with a chrome door similar to the front end of a '55 Buick.

The power line ran through a hollow ceramic resistor that had one of those one shot, thermal overload relays like you find in coffee pots. The resistor was in the power line to the magnetron. If the magnetron drew too much current the resistor got hot and blew the switch.

I had to search around to find a replacement relay with the same temperature rating. Replaced it and the oven worked for a few more years.

[Beachcomber]

Over a period of time, the magnetron may draw more current as it ages. This may or may not be enough to blow the fuse. According to most of the websites I've seen, the main fuse is the most common problem, with

75% of the faults caused by aging, high resistance fuses, or trouble with the door interlocks (microswitches).

The microswitches can arc over internally, if they frequently break any substatial amount of current.

Incidently, on most ovens, one of the microswitches is the fail-safe "idiot" interlock microswitch which causes a direct short across the AC power leads, should the door not be closed and if the magnetron relay actually is in the ON state.

Beachcomber

[Mark Lloyd]

The one I replaced was a standard-size .25 by 1.25 inch cylindrical fuse. Radio Shack called the replacement a "Microwave Oven Fuse". It was rated 15A.