Pops fuse when plugged in - Bosch HMV9305 Microwave Oven

More than likely the magnetron is the only fault.

There are a lot of possible causes, but I'd look at the door switches first, and the wiring connectors to them. Make sure the contacts on all the switches are opening and closing.

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You will have to remove the cover from the unit - It may have security screws that are a special kind and require a special tip - If you can get the cover off, with the unit unplugged, check the most likely ABC20 fuse on the small circuit board where the 110VSC power cord comes into the back of the unit - not sure why they don't leave that in a fuse holder on the back but when this goes - your unit seems dead - if you can check it on a meter you will likely find it is open circuit - replace it. Then plug in the oven before you put the cover back on - put in a half cup of water in a microwaveable mug and zap it for 30 secs - if the fuse holds and the water is hot, unplug and put the cover back on - Job well done - if the fuse pops again almost immediately then you have some other parts in that unit that are shorted and it may not be worth fixing further - they have become one of our 'throw-away' appliances

If this is a newer model under 7 years old, the problem is in the magnetron or the inverter board, cost to repair in either case would be excessive.

Assuming your power line voltage is okay, it would not surprise me that after 27 years, your high voltage capacitor is drying out and increasing its capacitance. This will cause variance in the high voltage output, which can stress the magnetron and increase current consumption.

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Replace the faulty/contaminated door switches.
That will do it.

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There is a high draw of power in the high voltage part...probably the capacitor is going bad...


Here is a tip that will help you to figure out what is wrong with your Microwave Oven....

Microwave Oven Basic Troubleshooting Tips

heatman101

There is absolutely no way to guess at the problem. You need to troubleshoot the circuitry with a meter to find the failing component

most often the fuse inside main cover needs to be replaced 1-2$ easily done with a phillips screwdriver remove cover look for a glass& metal on both ends fuse go to hardware store with it it's marked in volts and amps with letters after get the same one at store dont try to get a higher power fuse it could cause a fire ps. fuse just pops out of holder please make sure it's unpluged before doing anything

It does sound odd for it to blow the breaker. It should blow the fuse, not the breaker. But looking at the exploded view diagram, I don't even see a fuse! Makes me wonder if this is some foreign model. *grin* In any event, you will need to replace all the door switches since they all have been stressed by the same overcurrent. Also be sure that all the switch mount and door latch parts are activating properly when you open and close the door. The switches (generic replacements) are widely available from local appliance parts stores. If you need any other parts, you can see an exploded view and parts list here: http://www.geappliances.com/shop/prts/