Inline bus fuse continues to blow

You would better served replacing unit. Throwing parts at it is an unnecessary step.

Cause 1
If too much current passes through the microwave circuitry, the line fuse will blow. If the line fuse blows, the microwave won’t start. To determine if the line fuse is at fault, use a multimeter to test it for continuity. If the fuse does not have continuity, replace it. In addition, you should investigate and resolve the problem that caused the fuse to blow. If you don’t resolve the underlying issue, the new fuse will blow too

Cause 2

Main Control Board

The main control board might be defective. However, this is rarely the case. Control boards are often misdiagnosed—check all of the more commonly defective parts. If you have determined that all of the other components are working properly,replace the main control board.

Cause 3

Thermal Fuse

The thermal fuse cuts off power to the microwave if the microwave overheats. To determine if the thermal fuse has blown, use a multimeter to test it for continuity. If the fuse does not have continuity, replace it. The thermal fuse cannot be reset—if the fuse is blown, it must be replaced.

Since its a electrical isue cal a liscenced professiona to resolve the issue . Your microwave oven isnt at fault . I belive the supplay to it has issue and would have blown anyway.

If too much current passes through the microwave circuitry, the line fuse will blow. If the line fuse blows, the microwave won't start. To determine if the line fuse is at fault, use a multimeter to test it for continuity. If the fuse does not have continuity, replace it. In addition, you should investigate and resolve the problem that caused the fuse to blow. If you don't resolve the underlying issue, the new fuse will blow too. (Caution: The microwave oven can store thousands of volts of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the line fuse.)

Could be a lot of things but most probably a shorted high voltage diode assembly. If not that then the magaetron or capactors. Remember be careful there are high voltages even when the oven is unpluged. The capactors are usually charged and must be discharged. If you don't know what yor doing then time to get a qualfied tech.

Good luck

SEE THE steps and fix it. and diagrams attached.use the DVOM.God bless you

Line Fuse


Every microwave oven has a line fuse. This fuse is designed to blow if too much current is drawn through the microwave circuitry. The fuse can be replaced, but the underlying issue should still be investigated and resolved. Otherwise the new fuse will blow also.
Main Control Board


If the microwave is not working the main control board may be defective. This is not common. When a microwave stops working the problem is usually the line fuse or within the high voltage circuit; either the high voltage capacitor, diode, transformer or magnetron.


Thermal Fuse


If the microwave is not working the thermal fuse may have blown. It can be tested for continuity. Watch our fuse testing video for more information.
Thermoprotector


If the microwave is not working the thermoprotector may have tripped. This is a safety device to prevent the microwave from overheating. It can be tested for continuity to see if it's blown

Microwaves have an inline fuse inside that fatigues over time.Take the cover off,follow the power cord after it enters the housing to locate the fuse.

Disconnect from electricity. Remove screws holding outer casing and you will see the inline fuse. Make sure there is nothing that will cause the fuse to blow again. Always replace the outer cover before testing.

Did you replace the fuse yet?

Did the new one blow?

If so, and if it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If so, and if if it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

If the new one did not blow, and the microwave still makes a growling or grinding noise, but does not heat, you probably have a shorted high voltage diode or a bad magnetron.

Here are some links you or someone you know can use (in order given) for test help, but read the safety warnings first:

http://www.gallawa.com/microtech/diode.html (if it is NOT shorted, it's probably fine)
http://www.gallawa.com/microtech/cap_test.html
http://www.gallawa.com/microtech/mag_test.html
http://www.gallawa.com/microtech/xformer.html

There should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting & testing.

You can usually find helpful exploded view diagrams and order parts by entering your full model number here.

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

If it goes dead or blows the breaker (or GFI) when you plug it in or open or close the door, then there's a problem with a door switch or door switch mount.

See http://www.microwavedisplay.com/doorsw.txt

If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

Here are some links you or someone you know can use for test help, but read the safety warnings first:

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

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

sounds to me like the magnatron has shorted out. i don't know of a way to test them unless you have some high dollar equipment. a continuity test prob wont tell you anything. what reading did you get on the cap when you tested it?