Location of monitor switch for Sharp R-5A54B microwave

I answered your dupe post here:

http://www.fixya.com/support/t26419783-replaced_blown_fuse_blew_again

I am wondering which fuse is blowing?
There are at least two fuses fitted internally and in the UK at least another fitted in the plug of the supply lead.

It isn't wise for an unqualified person to replace the internal fuses of a microwave even if it is switched off as there is a capacitor inside that is capable of storing a dangerous amount of energy.

The reasons why a fuse blows is either because there is a poor connection close by that is generating a lot of heat or the the fuse rating is incorrect or of the wrong type (quick-blow instead of slow-blow) or the appliance is consuming more current than it should be.

Microwave ovens have a fairly simple working principle and there aren't many things to go wrong. When things do start to go wrong or components become tired it is usually translated into a loss of efficiency that can be measured by how long it takes to boil a measured quantity of water, for instance.
Periodically timing a measured quantity of water to boiling point is a good way to monitor the performance of a microwave and when efficiency falls significantly take it to the service shop before something destroys itself and causes more damage.

In my limited experience the magnetron could be failing but the internals of a microwave should remain a mystery to the unqualified.
I hope this helps a little.

Hello, there is a component that is pulling more current than it needs to be. I would check the microwave HV diode there could be some leakage to ground. Also, the mega-tron tube might not be working the way it should. If the mega-tron tube is going out. Just replace the microwave oven. It is to cost prohibitive to replace the mega-tron.


If you replace the microwave oven. Please recycle your old microwave. Boy Scouts, recycling centers, some charitable organization will recycle. GB...stewbison

The fuse is connected directly in series with the monitor switch. If it senses one of the door switches bad it will blow the fuse, this is there as an added safety to make sure the oven will not work without the door closed.

There are usually three and sometimes four door switches just inside and to the left of the control panel that are activated when the door interlocks with them. One of the switches is most likely bad. Typically it is the primary interlock which is on top. It can be checked with an ohmmeter, usually you can see it broken as the plunger will not go down or come up like the others.

They might be referring to a diode connected to the big silver capicitor and screwed to the case.
These can go short circuit causing the fuse to fail.

Here is a link you or someone you know can use to test it, but please read the safety info:

http://www.gallawa.com/microtech/cap_test.html

The best place to order parts for this brand is Encompass (formerly Tritronics).

Or you can call them toll-free at 866-779-5835.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

1.Problem with monitor door switch or
2. Problem with high voltage condenser.

I’m happy to help further over the phone at https://www.6ya.com/expert/vitaliy_f406165329c75ede

check high voltage transformer and high voltage diodes, condencer, and magnetron.,

Yes the internal fuse will have blown. I would also think the door latch switches and monitor switch will also need re adjustment

The door latch switches, and monitor switch assembly needs adjusting. With the door open the two latch switches should be normally open,and the monitor switch closed. Opposite way when door is closed. MAKE sure oven is unplugged before testing