No lights on front panel. When power is switched off and on it starts heating and will not switch off when off is pressed

The bottom door switch is defective, or its mount is loose, misaligned, or broken.

Replacing it's not a difficult DIY job.

The service manual is here. My help file on door switches is here.

FixYa doesn't notify me when there's a response, so if you have other questions, please contact me directly.

- William E. Miller, AS-EET
[email protected]
http://www.microwavecontrol.com
Microwave Oven Control Panel Repair Nationwide
"Recycling by repairing since 1982"

see the diagram and pictorial and proceed with common sense:
1) test the fuse for open or band contact with VOM,see the diagram attached how to do it
2)check the switch door hook or door release button,when they are broken they do not touch the switch, and will NOT start. test for open
see the diagram

Door switches

If one of the door interlock switches is not switching properly or there is a condensation problem on the sensor control panel, either can cause the turntable/light/oven to come on even though the "Start" button has not been depressed due to the wiring of the switches or it can take the mains power fuse out and stay faulty.
Check for faulty door switches and/or contaminated actuators.

Alternatively, the magnetron, supply or HV diodes can fail and take the mains fuse out.
I hope that helps.

Hello :

It could be bad door switch or loose door switch mount . There are plastic mounts inside the microwave which hold the door switches and onto which the door latches lock when you close the door.

The screws on these mounts may be loose. If they get too loose, the switches will not be activated properly.

or it could be problem with the control panel .

good luck .

please rate !

　

it sounds like it one of your micro-switches inside that control the power to the doors, if one of the switches is bad, it would cut the power , the panenl will light, the turn table will work, the fan will turn on , but you will not get any heat at all, micro-switches run depending onthe unit from 5-10 bucks, when you open the unit you will see the one that is bad, is usually bent or the connector might be burn or melt, good luck..!

HI. your control board has failed. you will need to replace the control board asap if possible.

I had the same problem some years ago, and in my view it is caused by a design fault. There's a circuit board behind the front panel with tiny tactile switches that get pressed by the front panel buttons. But the **** design is that the switches aren't located behind the buttons, so the "engineering solution" that Sharp has used is to mount each of the buttons on a framework so that a sticky out bit from the button presses the appropriate switch. The problem is that the framework is made of plastic and so will eventually give way. Some 5 years ago I opened up my microwave and repaired the framework. When it went again yesterday, it was too far gone to repair. I could purchase a spare button panel from one of the spares suppliers, but for some GBP 8 or so.

Wanting an instant solution, I went a bit further. I removed the switches and soldered short trailing leads to their contacts. I glued (with epoxy) the switches back onto the circuit board so that they were directly behind the buttons, and then soldered the trailing leads from each switch back to the original switch locations. This meant redrilling the holes for one switch as the original holes were now obscured. I then cut off the three buttons from their framework (it was just the Stop, Start and Power level buttons as we never use the others) and trimmed off any projections to make them flush on the back. I filled the hollow of the button with modelling clay, and then expoxied a thin (2mm) layer of rubber on the back. When re-assembled, the buttons simply float in the hole in the front panel, but don't fall out as the switch is just behind them. They now work better than ever before, as they're pressing directly on the switch, rather than indirectly.

For disassembly (from memory), I removed the six or so screws holding on the main steel cover (at the sides and on the rear). There was one screw inside the casing securing the front panel assembly which, when removed, allowed the front panel assembly to be removed by lifting slightly and then pulling out. Disconnect the cable connectors (taking care to label where the yellow & red power connectors go. On the front panel assembley there are two circuit boards on top of each other. Remove the top one and the connector from it to the bottom one. The bottom circuit board is screwed in with 4 screws. Once the bottom board is removed, the button panel lifts out and you're ready to consider whether you're up to my repair method or whether you want to order a new button panel.

It may have taken me a while to complete this, but it gave me the satisfaction of a repair with no parts required, and the confidence that it will last, and can be tweaked if required. So my R24ST lives again!

I found this on another blog and it worked for me.


Model #KB6024MK, this is a Sharp microwave drawer that would open and close properly, but when started would not heat. These drawer units will sometimes close properly, but not enough to actuate the interlock switches to power the magnetron. A quick test is to turn the unit on and press in on the drawer handle while it is running. If you start hearing the low hum of the magnetron, the interlock assembly is out of adjustment. Removed the left side panel and gained access to the switch mounts to do a quick adjustment so when the drawer closes, the switches close properly to allow operation. It may take more than one adjustment to make it work properly so test it several times before reinstalling the side panel. It should work properly when the drawer auto closes and should not require any manual manipulation from the user.

This is usually caused by either a bad door switch, a loose door switch mount, or occasionally a problem on the control panel.

Even though a door switch clicks, it may still be bad inside. Its continuity must be checked.

Door switch or mount trouble can be caused by slamming the door or by opening the door while it's cooking without hitting the Stop pad first.

There are plastic mounts inside the microwave which hold the door switches and onto which the door latches lock when you close the door.

The screws on these mounts may be loose. If they get too loose, the switches will not be activated properly.

Sometimes it's a broken tab on the switch holder, allowing the switch to rotate just out of position. This tab can be hard to see, since it is under the bottom edge of the switch.

One test that sometimes helps is to gently lift up (and/or push down) on the door or handle as you try to start it. If it works or tries to work, then it's a door switch mount or door alignment issue.

If you or someone you know decide to look into it, we have critical information on safety, disassembly and door switches at our site, and our link is at our listing here on FixYa:.

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

Glad you found the "mini-manual". It's very helpful when troubleshooting & testing.

If you only need a switch, you can order one from us for $5 postpaid.

If you think the problem is on the control panel, we repair these nationwide by mail for $39.95 postpaid in most cases.

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

You may have a control board issue. Thank God for safety switches.
This is a problem that an integrated circuit tech. can repair, but it may be costly.
Decide how much you want to put into this oven vs. buying a new one.

Contact me once you decide and I can help you find a service center.

Thank you,

Dave E. (Illeagle)