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Not typical microwave oven issue

my microwave - an old Sharp w/convection - has a nasty habit. When the power goes on and off, as in a storm or not, occasionally it will spontaniously start up, usually with the convection feature on - 'cause it gets very hot. I haven't noticed that the microwave was on, just heat.

has anyone fixed an issue like this? I'm thinking the low voltage power supply needs some new caps. Maybe some transient suppression on the Triacs. Is there any "typical" circuit or block illustrations for this. I can reverse engineer it if I can get to it but some idea would help.

Otherwise it works fine. I just need to remember not to leave it plugged in.

thanks

Reply to
bill
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I have a very similar microwave, When thepower went out last afterwards as soon as the door gets opened it throws the circuit breaker outside. Has anyone got any tips here? For their age these ovens work pretty good.

Reply to
toranaboy14

Check the MOV across the line. Mine died and emitted smoke after a couple of years.

Reply to
Homer J Simpson

No idea on how to fix this, but I would suggest leaving the door open when not in use, rather than remembering to unplug it.

Reply to
JW

this is an interlock failure, and is a dangerous condition. The resistor that pops the breaker/fuse can not be counted on to continue doing its job repeatedly, so if it starts behaving again of its own accord its just got one step more dangerous, and now has just one switch between working and frying you with door open - and bear in mind the other one has already failed.

Note interlock failure can be caused by door misalignment, bad microswitch or a mechanical interlock problem.

NT

Reply to
meow2222

As snipped-for-privacy@care2.com said, this is a safety feature.

The interlocks prevent you from being irradiated. The interlocks have to engage in a certain order or the fuse in the oven will blow (or the circuit breaker at your Breaker box trips). Here is a link to the RepairFAQ about the interlocks:

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toranaboy14 wrote:

Reply to
nvic

This makes sense, a couple of months back I had to realign one of the switches because the thing wouldnt run. The missus has a habit of slamming it shut half the time. Ill look into it later on and if nothing comes from Ill look for another.

Thanks all.

Reply to
toranaboy14

Slamming the door can misalign the switches. Train her to close it.

Reply to
Homer J Simpson

even a block diagram would be nice, huh? When you just plug it in with the door closed, does anything on the panel come on? Most have a fuse in line (or should) and if the current draw is enough to pop your house breaker it should pop the internal fuse first. Your breaker may be a GFI if you are plugged into a kitchen outlet. In that case, if you measure between a prong and ground on the micro plug you may find a leakage resistance. About the only thing connected with the door open that isn't with it closed would be the internal lamp. I suppose there may be some that turn off the control ckt until the door is opened. If so, the low voltage power is where to look. still, read again above re current.

Reply to
bill

GOOD CALL - kitty cat

I wondered what that "MONITOR" switch and resister (or not) was for. Logically, I should have figured it out.

That Monitor switch has a short life cycle. I wouldn't trust it after ONE activation.

Reply to
bill

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