GE Spacemaker microwave JVM140G just stopped working - no power, no lights, no exhaust - NOTHING Is there an internal fuse? The circuit breaker is not tripped.

Probably not a house fuse. Typically good or bad!! Have you tried it in a totally different outlet?? Could be a bad connection of your circuit breaker to the bus bar in your circuit breaker panel. Try it on an outlet on a different breaker. Or have someone check the power at the outlet when it is running and see if the voltage is dropping.

Did you check the internal fuse? Often when everything is dark the fuse that protects the microwave is blown. Take the old fuse to your local hardware store and they will have a replacement for you. Should cost less than $5.

your power transformer for the magnetron could have a shorted primary power winding,the door safety interlock switch could be mis-adjusted,this normally blows the internal unit fuse,a shorted high voltage capacitor,or diode,a bare wire inside the unit,more than the microwave on that circuit or a weak circuit breaker in the house power panel

theres a fuse inside the unit

• Make sure that the microwave is plugged into a grounded outlet. It must be a 3-prong outlet.
  
• Make sure the clock is set.
• Check to see if a programming sequence was entered. Sometimes improper programming or a program sequence such as delay start can cause the touch panel to be non-responsive. Unplug microwave or turn off house circuit breaker for 30 seconds. Plug back in, or reset circuit breaker, and try reprogramming unit.
  
• Check the house circuit breaker or fuse box. If the microwave is DEAD and there is no display and nothing works- the problem could be a blown fuse or tripped breaker.

check fuse inside unit microwave has a fuse around 15 to 25 amps get at local hard ware store u should discharge capacitor before installing fuse not nessary in microwave

It could be a bad in-line circit breaker fuse. Unplug the microwave and take the outside cover off. Look for the in-line circuit breaker fuse. Use a plastic fuse puller (not your hands or a metal tool as there is still voltage stored in the microwave even when it is unplugged). Look at the fuse and see if it is blown. (The metal wire running length of tube will be broken. If you have one, test with an Ohmmeter.

The control circuits for the cooktop lights and the hood fan are spearate. The problem is indeed with the control unit. It's usually caused by either the filaments shorting when the lamp blows or by removing or installing the bulbs while the oven is still plugged into the power line. We regularly repair these nationwide for $32.50. Details of our service, as well as *critical* safety and disassembly info at our site, which is linked at our listing here on FixYa: http://tinyurl.com/yzjozk