Is it always 59 seconds? Reason I'm asking is some did not have the protective plastic removed from the case when they were installed and had a LOT of over heating troubles. The Micro would get too hot and shut off. But if your shuts off at 59 seconds every time, this probably isn't your problem.
Rob & Kathy
97 Southwind
2004 Honda CR-V
Good Sam Member since 1992
Do a search of all of the forums for "Sharp Microwave" and you will find that this condition has been reported. In fact look at this post 59 seconds.
Cliff
You need to take in to an authorized srv facility for Sharp. It has to do with a damper door malfunctioning inside the microwave. Seems to be a big problem for sharp