Question about Sharp Microwave Ovens
This has been a fantastic oven, but recently the start button has started sticking - you have to press it hard several times to get it to work. At first I thought it might be dirty, but I tried cleaning the area around it and it has made no difference. I guess it needs a new switch - any ideas on how to replace it, please.
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!
Posted on May 06, 2009
I don't have the service manual for that UK model, but my experience tells me that under the buttons there is either a set of board with mechanical switches or a membrane keypad.
Either way, that membrane or switch board is likely what you'll have to replace.
For generic disassembly help, see:
Info on ordering Sharp UK parts / spares is here.
If you're in another country, you can visit Sharp's world portal here.
We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.
Posted on Feb 09, 2009
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Dead appliance, power on wall outlet.
SAFETY IS PARAMOUNT!
this only if you are competent.
your appliance has absolutely no functions at all, remove it from the
mains supply, remove the case and see where the mains lead goes in to
the appliance and follow the cable until you find the main fuse.
ONLY USE THE SAME TYPE AND RATING OF FUSE TO REPLACE IT.
The usual cause of this fuse failure is the door switches are contaminated or sticking. Check the door switches before putting power back on to the appliance.
Hope this helps.
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