I have a Sharp Microwave model R-1870F. We set it for time bake and left. When we returned it had baked OK but the unit was dead. I checked and fuse inside the microwave was blown (250v - 20 amp). I looked over the wiring inside and nothing looked shorted. I installed a new fuse and started the microwave. It made a loud buzzing sound and blew the new fuse immediately.
Make: SharpModel: R-1870F
did you smell a electrical odor
No I did not smell electrical odor. That was the first thing I checked. There was no storms at the time either. I owned an alarm company so I am competent with meters and such if you want me to check anything.
sorry to be so long ,, have to take my insulin ,,, it will be eather a diode, capacitor or hi-voltage transformer ,, all these parts are hi-voltage so you need to read this before you get into it ,, here is links to the parts:http://www.searspartsdirect.com/partsdirect/getSubComp.pd?modelNumber=R-1870&productCategoryId=0123370&brandId=0958&modelName=MICROWAVE&diagramPageId=00001&componentDescription=CABINET%20PARTS&documentId=50020288&blt=06be careful and should if you need me / larry
Over 35 years of in home appliance repair and service