Repaired microwave keypad looks as good as new

microwave_keypad_repair

Instructables user [Rohit] had an out-of-warranty microwave with a broken membrane keypad. Much like our friend [Alexandre] from Brazil, he found the cost of replacement parts beyond reasonable, so he had to find a way to repair it instead.

He disassembled the front cover of his microwave to get at the main controller board. Once it was detached, he removed the keypad’s cover to get a closer look at the matrix underneath. While taking notes on how the matrix was wired, he found that some keypad traces connected to other traces rather than buttons. He says that they are likely used by the microwave to detect that the keypad is present, so he made sure to short those traces out on the controller board when he wired everything back together.

He replaced the aging keypad with microswitches, but rather than mount them on the front panel of the microwave, he drilled holes for each switch so that he could mount them inside the face plate. Once everything was wired and glued in place, he re-mounted the keypad’s cover. Now the microwave looks stock but has firm, reliable, user-serviceable buttons that are sure to last quite a while.

Comments

  1. monster says:

    wonder how user serviceable it actually is with all that glue on each button. if he cracks that plastic removing a failed switch he’ll have nothing to mount the new one to

  2. Elias says:

    It’s hot glue. You just reheat it and it melts again.

  3. Rachel says:

    Those aren’t microswitches. They’re tactile PCB buttons, which are far less reliable. In fact, they use the exact same internal mechanism as membrane switches.

  4. j8g8j says:

    Nice retrofit. I bet it outlasts the original keypad. One suggestion: Some form of backing material to reinforce the glued-down micro-switch buttons. Otherwise, they are likely to be pushed-out eventually. (A stiff piece of cardboard may suffice.)

  5. ejonesss says:

    most stuff today is throw away.

    microwave, window air conditioner many cooking appliances all made to be thrown in the garbage after a couple of years

    the fact you fixed yours shows you intend to keep your microwave for a while longer.

  6. Rohit Mahajan says:

    Thanks for the kind words and feedback gang! It was at 8 views yesterday, today it’s past 800! :D
    @monster- That’s exactly why I went for hot melt glue… easily removable. Like Elias said, you just reheat it. I have an old soldering iron that could do the job.
    @Rachel- Those are DEFINITELY microswitches. I checked!
    @j8g8j- The front label and the face plate itself stop it from being pushed further in. I did consider making a PCB and mounting the buttons, but then it was a lot of work for little gains.
    @ejonesss- Certainly! Better keep filling my tummy than go to the landfill!

  7. veneficus says:

    Total of 22 microswitches, if each cost $0.25, the total repair (not counting the labor) would cost $5.50, not bad at all.

  8. Rohit Mahajan says:

    @veneficus- Actually, I got 25 buttons for 25 bucks- that’s equal to fifty cents! Of course, if you were to add the cost of solder and hot glue, it would only be marginally higher. But still less than 1/8th the cost of a new membrane, not including labour. Not too bad since I see it as entertainment rather than labour :D Fixing things amuses me :)

  9. Mad Max says:

    Ever since the egregious concept of “planned obsolescence” came up, products are built to last not a second longer than what consumers still consider as acceptable. Nobody ever builds anything anymore to last as long as possible.

    They realized a long time ago there’s no money to be made that way, and having a great reputation for endurance and quality nowhere near measures up to the money that can be made by selling a slightly cheaper thing 3-4 times to the consumer in the same time frame he might otherwise have to buy just one.

    Take a good look around, and you’ll notice that every single business entity today would much prefer you (and tries his best to get you) to _rent_ stuff from him as a subscriber rather then _buy_ and never pay again (as long as the product keeps working). From banks to mobile providers, music stores, and yes, even OSes (MS would love that). Nothing beats a guaranteed steady revenue stream, innit?

    So there’s nothing to be surprised about really. But I do find this approach devious and immoral and I fight it every time I can. Much like the featured DIYer here did – nice job of keeping that oven in service!

  10. Rohit Mahajan says:

    @Mad Max- There was no question whether it could be serviced- the parts were in stock. But I, too, am against the concept of making something that only works a while, and maximises profits. Membranes are easier and cheaper to manufacture and fit than buttons.
    Plus it’s fun to add something custom to your stuff :) It’s like that saying… the journey is better than the destination. But, as hackaday readers know, precious few reasons are needed to open up something and see how it works :D

  11. sun god says:

    Okay SO I have a Jeep Key Fob that doesn’t work. The rubber pads have seemed to worn out. When I take a flat screw driver and short the contacts for a button everything works just fine.

    I was thinking of installing micro push buttons on the pcb, any other ideas. I’ve tried cleaning the contacts with Alcohol no luck. The rubber pads arn’t metalic anymore.

    Maybe I should start a thread in the Forums.

  12. Rohit Mahajan says:

    This idea would work…. but keep in mind that you’ll need to keep the key fob water-proof as well.

  13. cutandpaste says:

    For conductive rubber membrane keypads, of all kinds (from Motorola Centracom dispatch consoles to key fobs, and probably microwave ovens, too):

    I have had a 100% rate of success using Deoxit DN5 to just clean up the rubber and the contacts a bit. Squish the fluid around with on the contact area with a Q-tip to slightly abrade and absorb things, wipe up the remaining mess (if you feel like it), reassemble, and it works like new.

    Every. Single. Time.

    Lesser methods (pencil eraser, alcohol, Windex, conventional contact cleaner, sand paper, whatever) have been far less effective, in my experience, than a quick shot of DN5.

    I bought a can of Deoxit DN5 5 or 6 years ago, and it’s finally getting to the point that I’ll need to replace it — it doesn’t take much to get it done.

    (Nope, I don’t work for them, or sell the stuff. It’s just my experience.)

  14. Rohit Mahajan says:

    @cutandpaste- That sound interesting, I’ll have to look up if it’s available locally.
    The problem with this one was not with the matrix itself- it was the ribbon cable. No easy and reliable way to fix it… the tracks were broken, and covered with a plastic layer.

  15. Congratulations for the nice job!!! But if I were you, I’d put the switches in a perfoboard behind the panel, so it would be stiffer and you could press it without being afraid of ungluing a buttom.

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