How do you change the fuse in a Microwave?

Discussion in 'Shop Talk' started by r.h. in okla., Feb 14, 2005.

  1. You would think being a former electrician I should know this right? Well I've done all kinds of electrical wiring from 120/240 volt residential to 480 volt 3 phase in industrial buildings but I have never changed a fuse in a Microwave appliance. In fact I have a Panisonic microwave in my house that we have had from somewhere of 15 to 20 years and it still works like it did when we first bought it. I have never had any problems with it. It is a little slow compared to the new microwaves but it still heats up and cooks food. Well last September we bought a new microwave oven for our donute shop (that went under) but we only used it for about 3 months and then all of a sudden it quit working for us right about the time we decided to close down. Well I've looked all around it trying to decide whether to take the back off or not or whether that little box with a cover on it inside the oven part is the fuse. But I have tried removing it and it wont come out. So I'm not sure if it is the fuse or not and I don't want to remove the back if the fuse is not located in there. So, any suggestions?
     
  2. Forgot to mention. Somewhere during getting ready for the big opening of the donute shop all the paperwork that comes with a new microwave must have gotten throwed away so I can't take it back and don't have any diagrams to show me where the fuse is located.
     

  3. agmantoo

    agmantoo agmantoo Supporter

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  4. Sorry agmantoo but that site only recommended that I get a qualified technician to replace the fuse. It didn't tell me how.
     
  5. agmantoo

    agmantoo agmantoo Supporter

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    Sorry about the bad info. Here is what I would do and have done. You have to remove the cabinet. Remember that working on Microwave apparatuses is dangerous due to radiation. Never plug the unit in with the cabinet removed! Once you are inside you should just nose around until you find the fuse provided it has one. The most common problem that I have seen is that there is a relay that controls the supply power to the magnatron. Microwave ovens use a lot of power but for just a brief period and the relays crap out. I replace the relay with one from a AC.
    PS...I went to the site and you were too easily turned away. I got a complete breakdown on the components in my Microwave and I saw a trouble shooting guide. Yes, it suggests that you get a technican but once you see the troubles shooting list and the pics of the components you should be able to proceed! some of the parts list http://www.repairclinic.com/0080.asp?PageNum=2
     
  6. Cosmic

    Cosmic Well-Known Member

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    The first thing you do is discharge those high voltage capacitor(s). Best to have a discharge stick which is built by using a heavy copper rod and a series resistor / heavy copper flexible wire strap with a clip. This gives a RC time constant and limits the discharge rate to protect both yourself and the equipment. Clip goes to ground, you touch anything you believe may store a charge. Some designs may have incorporated discharge resistors but you are fool to trust such things. Only takes the one odd time for you to buy the farm.

    Lot of the better techs will put a jumper short on it after they think it is discharged. The microwave is one of the most dangerous pieces of tech gear to work on, especially if trying to troubleshoot it hot.

    Many times the fuse may not look like a fuse. A number look more like mica capacitors, sometimes square.

    These microwave puppies can not just jolt you but can kill you. Many microwaves will have the symbol or designator silk screened somewhere. Like F-1. Some might have info pasted inside the covers.

    Want to be thinking why it might have blown a fuse. Could be a variety of causes.