22 Jun
2004
22 Jun
'04
5:58 p.m.
[Tony Duell]
It's been a while since I had it open, but I'm fairly sure my oven's
door switches don't work that way.
Then it's very unusual. Normally over here there's at least one swtich in
series with the mains (live wire) to the transformer, and one across the
mains after that one. Normally the first one is all you need (door open,
switch open, no microwaves), but the second one shorts out the mains
should the first one stick closed. This will blow the fuse, of course. If
you have a microwave oven that blows the fuse as you open or close the
door it's a fair bet that the switches are misaligned.
Some ovens have a current limiting resistor, of about 0.25 ohms (!) in
series with the shorting switch. This is often shaped like a fuse and
fitted in a normal fuse holder. Needless to say it must not be replaced
by a fuse!
-tony
[failure
modes]
Most of the time it's the door interlock microswitches (one of them
is _designed_ to short the mains if the others stick closed),