Can Membrane Switches be Repaired?

[pauldow]

I picked up a decent looking dishwasher from the landfill. I got it cleaned up (I think they washed sneakers in it.) and it runs fine, but the cycle selector membrane switches will only work when I squeeze an area where two segments are connected.
From the strip of switches & LEDs, there's a glued connection to a ribbon strip going to the control module.

Is there a way to reset that adhesive? They only sell the control panel as a complete unit for about $125/
It's a Maytag (AKA Whirlpool) MDB8751AWB

[SteveNielsen]

Re: Can Membrane Switches be Repaired?

Attach good pictures of the membrane switches.

[stj]

Re: Can Membrane Switches be Repaired?

i'v seen people replace the rear of membranes with stripboard and push switches - you cant tell frm outside.
although i imagine they have a nice tactile feel afterwards!

[pauldow]

Re: Can Membrane Switches be Repaired?

Thanks for the information.
Here's some photos

The first is what the dishwashing human operator sees


Next is the full width of the switch strip from behind.


And finally, the area where the switch strip, and the connector meet. When I squeeze here, it works.

[stj]

Re: Can Membrane Switches be Repaired?

that'sa complex bastard, i'v never seenamembrane with led's in it before.
not seen onewith a bonded extension cable either.

isit really a membrane, or is the rear part fiberglass board?

[pauldow]

Re: Can Membrane Switches be Repaired?

Ah, your right. I wasn't looking at it close enough. I thought the black front plastic with the switch labels is what gives it the stiffness.
The part with the contacts and LEDs is stiff fiberglass. is has the slot where the flexible connector is attached.
I think I'll try some heat and pressure to see if it will make it stick better. I don't have much confidence that it will make a reliable connection though.

[stj]

Re: Can Membrane Switches be Repaired?

peel the plastic off the board,
it will probably use metal discs on the back of the buttons.
clean them, and the pads on the board.

if that dont work, you can get *very* low profile surface-mount push switches you may be able to solder to the board.
they are often found in fones & stuff.

also use a meter to check the connection between the ribbon and the pcb.
if it's fucked i'd replace it with some ribbon cable from an old floppy/hd cable or something.

[pauldow]

Re: Can Membrane Switches be Repaired?

I got some testing done, and the switches are all OK.
I took a small heat gun, and heated the connection area in the third photo to about 100 deg C., and then pressed it together. I also cut the slot larger where that strip goes down into the door so the joint has a bit of a shallower angle. I'm hoping that will put less strain on the glued joint than the 90 degree angle it was made with.
It's working so far.
Sometimes those old mechanical switches are the best. They often don't look as nice, but they were reliable.