Microwave oven

I have a GE microwave oven that just stopped heating. I have checked
and found the problem to be in the high voltage section. I found the
high voltage diode shorted and the high voltage capacitor going bad.
I've replaced both of these, but it still does not heat. When I
rechecked I again found the diode shorted within 1 minute of running.
The magnetron tube was replace 3 months ago and the transformer tests
good. The magnetron tube show no short to case. Also no shorts in
transformer, and correct ohms on each winding. Has anyone run into
this, or have any ideas?
Retired

 

It sounds like the magnetron is shorting or pulling too much current when it
is powered up.

Is for myself personaly, when my personal microwave oven fails, if it is not
a small easy fault to service, I replace the complete oven. Many of the
models now carry a 3 year warranty. If you amortize the cost over the 3 year
period, the cost is very cheap.

--

JANA
_____


I have a GE microwave oven that just stopped heating. I have checked
and found the problem to be in the high voltage section. I found the
high voltage diode shorted and the high voltage capacitor going bad.
I've replaced both of these, but it still does not heat. When I
rechecked I again found the diode shorted within 1 minute of running.
The magnetron tube was replace 3 months ago and the transformer tests
good. The magnetron tube show no short to case. Also no shorts in
transformer, and correct ohms on each winding. Has anyone run into
this, or have any ideas?
Retired

 

What do you mean by "going bad"?

Was it heating during that 1 minute?

There's only 4 parts there - HV transformer, HV capacitor, HV diode,
magnetron. It's unlikely that the HV transformer could go bad in a
way that would not result in a blown fuse or lots of smoke.

The magnetron could be defective and show up only with HV applied.

What abouut the condition of the waveguide and the rest of the oven?

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The capacitor showed a short to case after running for about 2
minutes, but would again test OK after being off for a while. The wave
guide and the rest of the oven look A1. The magentron look good also.
No ;I got no heat in that 1 minute that I ran it. I had a cup of water
in it, and it stayed cold. I am beganning to think it is the magnetron
even though I can not prove it.

 

The capacitor showed a short to case after running for about 2
minutes, but would again test OK after being off for a while. The wave
guide and the rest of the oven look A1. The magentron look good also.
No ;I got no heat in that 1 minute that I ran it. I had a cup of water
in it, and it stayed cold. I am beganning to think it is the magnetron
even though I can not prove it.

 

The capacitor showed a short to case after running for about 2
minutes, but would again test OK after being off for a while. The wave
guide and the rest of the oven look A1. The magentron look good also.
No ;I got no heat in that 1 minute that I ran it. I had a cup of water
in it, and it stayed cold. I am beganning to think it is the magnetron
even though I can not prove it.

 

I used to fix them years ago. I made a resistive divider which I could
use to measure the high voltage at the cathode using a conventional
voltmeter. If the heater windings are OK and the voltage is about 2500
(IIRC) then replace the magnetron.

Cheers.

Bill.