Microwave either make noise or turns off after 3 seconds

I have a Panasonic NN-P295SF microwave that sits over the range. It came with the house when we bought it and it about 10 years old (manufactured in 2004). Last week it started doing this thing where it would run for three seconds, then stop. Later the same day it would run, but it's making a weird whiny sound when it starts and briefly when it stops. I believe the sounds is coming from the motor powering the magnetron cooling fan.

Video here: http://1drv.ms/1KdmmEH

I have an avionics background but it was a long time back and I have zero experience with appliances. I've tried to find schematics for the oven, but no luck. Someone suggested checking the thermostats. There seem to be two of them. One is <1 Ohm, the other is infinite. I have no idea if they're supposed to be like that or if one of them is busted.

Picture here: http://1drv.ms/1GxxtU2

Seems to be this model: http://www.asahikeiki.co.jp/en/product/us-622/

I'd really appreciate any advice on how to troubleshoot this. I know microwaves are dangerous. If the magnetron or high voltage capacitor is busted, I'll go buy another one because I don't want to piss around with that stuff. But I'd like to save some money and repair this one if I can.

Thanks!

 

[N_Cook]

On 21/07/2015 03:44, aarebrot@gmail.com wrote:

I have a Panasonic NN-P295SF microwave that sits over the range. It came with the house when we bought it and it about 10 years old (manufactured in 2004). Last week it started doing this thing where it would run for three seconds, then stop. Later the same day it would run, but it's making a weird whiny sound when it starts and briefly when it stops. I believe the sounds is coming from the motor powering the magnetron cooling fan.

Video here: http://1drv.ms/1KdmmEH

I have an avionics background but it was a long time back and I have zero experience with appliances. I've tried to find schematics for the oven, but no luck. Someone suggested checking the thermostats. There seem to be two of them. One is <1 Ohm, the other is infinite. I have no idea if they're supposed to be like that or if one of them is busted.

Picture here: http://1drv.ms/1GxxtU2

Seems to be this model: http://www.asahikeiki.co.jp/en/product/us-622/

I'd really appreciate any advice on how to troubleshoot this. I know microwaves are dangerous. If the magnetron or high voltage capacitor is busted, I'll go buy another one because I don't want to piss around with that stuff. But I'd like to save some money and repair this one if I can.

Thanks!

Isolate the fan and drive from a suitable bench supply or variac, if its
not obviously a bearing problem

 

I have a similar circumstance. GE microwave
bought 13 yrs ago. Cuts off less than 5 sec
after pressing Start. Display blacks out
or displays "full"(all elements) then blacks
out.


After 2-3 more attempts it finally completes
my cooking cycle. I got tired of resetting the
clock, so now it's just blank.


No odd noises, however.