How can I fix the 59 second micro ?

This is a problem in one of the damper-related components, most likely the switch, but it may also be the motor or the damper door.

The damper is a door inside that opens or closes depending on cooking mode. If the controller senses that the door is not in the right position, it will shut down the cook cycle.

Sharp models stop after 59 seconds.

We have the 2 service manuals needed for this model and have uploaded them to our site here to help you:
http://www.microwavedisplay.com/r1870_r1871_sm.pdf
http://www.microwavedisplay.com/r1850_sm.pdf

You will need the free Adobe Reader to view or print them. You can download that here: http://www.adobe.com/products/acrobat/readstep2.html

The best place to order Sharp parts is Tritronics at http://www.wehaveparts.com

Good luck and be safe.

William E. Miller
prototech@usa.net
http://www.microwavedisplay.com

William Miller
August 2008