Runs for about 20 seconds then shuts off

There might be a problem with door switch for your microwave to be turning off after 3 seconds and the door switch will need replacement on your microwave.

This appears to be an Australian model and these are the only spares I can find. They do sell the latches. If the hinges are damaged and causing this, you will feel movement. Looks like it is time for a new one.

https://spares.bigwarehouse.com.au/index.php?cPath=46427_53341_57047

https://www.google.com/search?q=sharp+R-9X56+replacement+hinges

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Step 1:

Door Switch

If the microwave runs for a few seconds and then shuts off, a door switch might have failed intermittently. Check each of the door switches for any signs of overheating, arcing, or burning. Also check each of them for continuity. Replace any of the switches that is visibly damaged or that only has continuity intermittently

Step 2:

Main Control Board

If the microwave runs for a few seconds and stops there may be a short circuit in the main control board. Check other components first, these boards are often misdiagnosed.

Touchpad and Control Panel

If the microwave runs for a few seconds and stops the touchpad and control panel might be defective. There are several other components that can cause this problem, be sure to check any other components before replacing this board.

Touchpad

If the microwave runs for a few seconds and stops the touchpad might be at fault. This is not common. Generally speaking, if the microwave display is working and some of the buttons respond correctly but some don't, the problem is with the touchpad.

High Voltage Transformer

If the microwave runs for a few seconds and stops the high voltage transformer might have an intermittent short. This is not common. Check other components related to the microwave symptom first.

Thermostat

If the microwave runs for a few seconds and stops the thermostat might be defective. Watch our video on testing thermostat

Step 3:

Step 4:

Step 5:

Step 6:

use the DVOM tester and fix it. God bless you

see this causes and fix it. God bless you
Door Switch If the microwave runs for a few seconds and then shuts off, a door switch might have failed intermittently. Check each of the door switches for any signs of overheating, arcing, or burning. Also check each of them for continuity. Replace any of the switches that is visibly damaged or that only has continuity intermittently.

Main Control Board If the microwave runs for a few seconds and stops there may be a short circuit in the main control board. Check other components first, these boards are often misdiagnosed

Touchpad and Control Panel If the microwave runs for a few seconds and stops the touchpad and control panel might be defective. There are several other components that can cause this problem, be sure to check any other components before replacing this board.

Touchpad If the microwave runs for a few seconds and stops the touchpad might be at fault. This is not common. Generally speaking, if the dishwasher display is working and some of the buttons respond correctly but some don't, the problem is with the touchpad.
High Voltage Transformer If the microwave runs for a few seconds and stops the high voltage transformer might have an intermittent short. This is not common. Check other components related to the microwave symptom first.
Thermoprotector If the microwave runs for a few seconds and stops 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.

Thermostat If the microwave runs for a few seconds and stops the thermostat might be defective. Watch our video on testing thermostats.

see this causes and fix it. God bless you
If the microwave runs for a few seconds and stops the thermostat might be defective. Watch our video on testing thermostats.
If the microwave runs for a few seconds and stops 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.
If the microwave runs for a few seconds and stops the high voltage transformer might have an intermittent short. This is not common. Check other components related to the microwave symptom first.
If the microwave runs for a few seconds and stops the touchpad might be at fault. This is not common. Generally speaking, if the dishwasher display is working and some of the buttons respond correctly but some don't, the problem is with the touchpad.
If the microwave runs for a few seconds and stops the touchpad and control panel might be defective. There are several other components that can cause this problem, be sure to check any other components before replacing this board.
If the microwave runs for a few seconds and stops there may be a short circuit in the main control board. Check other components first, these boards are often misdiagnosed.
If the microwave runs for a few seconds and then shuts off, a door switch might have failed intermittently. Check each of the door switches for any signs of overheating, arcing, or burning. Also check each of them for continuity. Replace any of the switches that is visibly damaged or that only has continuity intermittently.

I typically find it is not door hinge issues but door switch issues, especially with sharp. You may heve a little movenent in the door hinge and that is allowing the door hook to move up and down on the plunger for a door switch that is probably a bit melted due to bad connections. If you check the door switches and look for any browning around the terminals where the wires push onto the switch you will probably find an overheated connectoion. Replace the bad switch and run better wires and better termninals to the new switch and it will probably be fine.

you need a door interlock switch bracket adjustment; or, possibly one of the microswitches replaced on that bracket. it is behind that control panel.

My mother had the same problem and she was going to trash it. Me being an extreme environmentalist, dint wanna let it go to the scrapyard. Got it down to Mumbai India checked with the engineers down here and rectified it. Problem was with the Magnatron. You would need to replace it. Well this one's getting repaired and off to a institution in need like the Home for the Aged rather than some scrapyard.

The door does come apart. Open the door and where the hinges are, there are openings where the hinges enter the door, this plastic piece (goes all the way around the door) With a small flat blade screws driver VERY carefully pry it (plastic) off, once off, check the latch end for the spring, typical failure for a Sharp is the little tab that the spring hooks to on the door, the only way to repair this so it will last is to replace the door frame. they are not too expensive, about $50 or so Part# FCOVB166KIT
is the door frame assy

It seems the micro switch for the door close have moved from and is not aline the door clip or the micro switch is faulty