Sharp convection microwave

I have struggled with mine for at least two years and finally got it fixed last night. Usually pounding on the front of the oven would get the power to come on and finally I pinned it down to tapping on the control section. Once opened up and plugged in I found a couple wires on one of the plugs when moved were causing the cut out. I then removed the circuit board and found cracked solder joints on the large pins of one of the connectors. I re-solder all the pins on that connector and the oven is fully repaired. Mid 1990 soldering robots didn't use enough heat on larger pins. This causes a fatigue crack after years of service and intermittent loose connection problems. Easy fix if you can solder and know where the cracks are.
microwaveoven review

Yep! The damper motor is the culprit! 5 years ago when I bought my Trek with the same microwave mentioned here, it stopped at the 59 second mark every time. I replaced both the microswitch and the damper motor and haven't had a issue with it since. Send me you email in a PM and I'll send you the document (with pictures)another RVer shared with me after fixing his.

I researched this problem for a relative and it was the damper motor on their model too.

Our Sharp convection microwave (model 1870, April 2004 mfr. date) did the same thing a few years ago. Stopped after 59 seconds. It was the damper motor. Not too difficult to replace and not too expensive to order online. It's been running fine ever since.

Denny and Cindy Henderson
fulltiming, currently at Nature Coast Landings in Crystal River, FL

I just watched this Is this your problem?
https://www.youtube.com/watch?v=QZHGdLP0AoI

If it is not the switch itself, you might have to adjust the lever that actuates the switch. Another words it just needs an adjustment of some sort so it has a little more positive action.