Jim shedden wrote:

Hi,

Looks like we back in service with a new magnetron! My guess is that
something shorted in the old magnetron when the unit heated and dumped
filament current through the diode, burning it open.

Thanks to all for the help. (Bert, as a result of your suggestion I
did power up the high voltage circuit with a new diode before
replacing the magnetron. The diode held, so I figured the capacitor
OK. Good to check because the new magnetron not exact and needed some
work to fit in.)

Interesting. I recently replaced the magnetron in a
GE JVM1642BB oven, only about 3.5 years old. In my case,
the HVR-1X diode measured 6V forward drop and maximum
reverse drop, the .86uF capacitor acted just like it
should (ohmeter reversal test) and the transformer
windings had appropriate DC resistance values.

Removing the magnetron, I found that the antenna
was partially burned/melted, though the filament
was .2 ohms or so.

Since the GE oven has a total of 10 year warranty
on the tube, I called GE and finally found the right
person to ask for a replacement tube. They sent one
out, along with a new stirrer (slightly changed
design) and a new HV diode. Kudos to GE for excellent
customer service.

I'd done a power measurement of the oven after
buying it, since it seemed to cook things more quickly
than expected. Sure enough, the original tube
was putting out around 1000W. The FCC test report
for this oven (really a branded Samsung oven with an
OM75P(10) tube) indicated around 770W output. I thought,
cool, I'm so lucky.

The new tube is good for around 765-770W. I suspect
now that the original tube was not quite right and
ended up killing itself. The power tests were done
using the calorimeter method, consistent with the IEC
standard. It just takes water and a thermometer.

My neighbor bought the same GE Profile oven the same
month from the same store that I did. His oven died two
weeks before mine did. My hunch is that Samsung made some
odd OM75P(10) tubes. Is this your tube? Is it under
warranty? Keep in the mind the GE ovens often have a
total of 10 years warranty on the tube.

Dana