microwave microswitch

Hi Gents, Well the microwave stopped working over the holiday. (Two year old Cuisinart) (Insert rant here about security screws.. torx with the pin in the center.) After opening it up I found that the main door micro switch was no good. T he warning on the inside says to only replace with other KW3A switches. He re?s a picture of what it looks like.

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125V, 16A. Only has NO contact populated.

I?m looking for some place to order this is the US. There are similar lo oking switches made by honeywell and sold by mouser or newark. These are V7 series. V7-6c17d8 14 ozf of force or V7-1c17d8 5.6 ozf of force. (only speced to 15 amps.. but should be fine.) I figure I should order a handful of them since there are *three* switches in the door. So first what?s an ozf? is it an ounce? I guess I can pull one of the w orking switches and measure how much force it takes to close it.

Here?s a link to newark.

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any other advise is welcome. (Hey I'm still searching for specs on the KW3A switch... like life time and contact force.)

George H.

Reply to
ggherold
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seems to go back to the days of slugs, ergs and all that antedeluvian stuff. Like pound-force, presumably ounce-force

Reply to
N_Cook

Ounce-*feet*.

Like pound-feet (or foot-pounds), but smaller, and like Newton-metres, but from before metrication.

Torque to operate the switch lever, I guess.

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Mike Brown: mjb[-at-]signal11.org.uk  |    http://www.signal11.org.uk 
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Reply to
Mike

*People's Shining Microwave Factory #7 with a Cuisinart sticker on it.

Standard warning: There can be enough juice in the big capacitor to zap you dead, even if the oven is unplugged. There's also a lot of RF floating around, sharp edges, etc. Be careful.

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For household stuff, Hazard Fraught Tool's $6 security bit set comes in pretty handy. Not what you'd use for production, but fine if you need it a couple of times a month. Chain hardware stores like Ace and True Value tend to carry this same set as well.

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There are usually three microswitches. One of them opens the 120 V line from the wall, like you would expect. One of them switches a low-voltage circuit to the control board. One of them *shorts* the

120 V line on purpose, blowing the fuse in the microwave, if the other switches operate in the wrong order. So... check the main fuse as well. Also look at the plastic assembly that interfaces between the door latch prongs, the door open button (if equipped), and the microswitches; if this plastic cracks or gets bent, it can either push too hard on the switches or not push them at all.

They may not all be exactly the same. Sometimes the one that goes to the logic board has both NC and NO contacts.

Ounce force. (As distinguished from ounce mass.) 1 ozf is about

0.278 N .
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Ten minutes longer than the warranty on the microwave. :)

This Taiwanese vendor has several flavors of KW3A switch, with a good amount of specs on each one:

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Standard disclaimers apply: I don't get money or other consideration from any companies mentioned.

Matt Roberds

Reply to
mroberds

Thanks for the nice response Matt. I did short the cap before poking aroun d inside. Once I found the bad switch I shorted the spade lugs and the mic rowave ran just fine... so no other damage. I measured the plunger force last night. ~5 - 6 oz. So I'm going to get so me of the honeywell switches. They list a electrical life of 100k operatio ns vs 50k for the specs I found for the KW3A. I was thinking that as well as the average time to failure it'd be nice if they also included the stand ard deviation. (I guess that's too much to ask.)

George H.

Reply to
ggherold

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