Fixing a rubber button

[chartle]

I have a machine that has a control pad that uses those rubber buttons. The ones that have a bit of conductive material on the end of it and it shorts two traces on the PC board.

One button just doesn't work well if at all. I've cleaned the contact area on the PC board and the button. I also tested the contact pad and its fine. It seems to be the conductive spot on the bottom of the button.

I think I has seen kits to fix this somewhere, but I'm not sure if its just something to clean the contact pad.

I can't even Google it right because I can't even come up with the right term for this button.

thanks

[Rerouter]

though i was not too proud of it, i have fixed one of these type mechanisms before with a tiny spot of tin foil super glued to the bottom, and in another case managed to solder a tiny spring to one terminal with a few mm overhang towards the other side, so when the button was pressed it made the long lead form contact with the other contact, in both of these cases, it was what was available and simply to get the thing working

[robrenz]

Caig makes some good stuff so I would personaly try This or direct from Caig Here

[madires]

One button just doesn't work well if at all. I've cleaned the contact area on the PC board and the button. I also tested the contact pad and its fine. It seems to be the conductive spot on the bottom of the button.

That's a common problem which can be solved easily with a new graphite coating, e.g. using CRC GRAPHIT33. Fixed a lot of bad remote controls over the years. Use a brush or use a piece of paper as spray mask by cutting matching holes.

[SeanB]

Depending on the button I have fixed a few by either placing aluminium foil through a paper punch to get the right sized rounds or finding a similar sized button on an old remote and cutting it off, then carefully glueing the new one in over the old. If the pad on the board is worn as well then you will need the Graphit33 spray and a fine brush ( and work fast before the solvent evaporates) to repaint the pattern on the cleaned board, then leave to dry overnight and bake for 5 hours at 60C in an oven to firmly cure the binder.

[chartle]

Ok here is the fix so far.

I went the foil route. Couldn't find any at work but remembered I hadn't yet thrown away the foil wrapper  from my breakfast sandwich. Its really thin stuff. Then I couldn't find my really strong thin double sided tape that I sometimes use to hem banners (part of my job besides network/PC support is vehicle graphics, signs and banners).

So right now as a fix its the thin foil held on with removable double sided craft scotch tape.

I think i'll find some paint.

[SeanB]

A quick fix is to go to the local auto parts store and ask for a rear window demister repair kit, which will have the conductive silver paint in a pen for you to use. Not the best but pretty good for a quick repair.

[Fraser]

An interesting thread. I too have has this problem but have not tried the repair 'paints' as often teh remote control could be replaced cheaply.

I have got myself an Advantest R4133 20GHz spectrum analyser to play with. Its fine except for the buttons. The rubber button membrane feels like it has perished and every button pressed stays pressed !

Many years ago I bought a 3" x 7" conductive rubber button membrane from Maplin Electronics (UK). It was designed for projects but I never used it. I can't find it now and its probably degraded over the years anyway. Has anyone found a source of generic rubber dome carbon contact buttons that could be used to create a new button membrane for my R4133 please ?

Regards

Fraser

[chartle]

Many years ago I bought a 3" x 7" conductive rubber button membrane from Maplin Electronics (UK). It was designed for projects but I never used it. I can't find it now and its probably degraded over the years anyway. Has anyone found a source of generic rubber dome carbon contact buttons that could be used to create a new button membrane for my R4133 please ?

Regards

Fraser

How genetic? Everyone of these types of button arrays I have seen were designed exactly for that part.

[Fraser]

Agreed but I was considering affixing individual button domes over the PCB contacts to replicate the original button mat. The only other alternative will be for me to solder miniature SMT switches in place of the rubber contact domes.

The sadest thing is that I sold a working R4133 external keyboard for GBP30 the week before I was given the analyser ! 

Such is life.

Fraser

[ftransform]

fixing a rubber butt is what the thread appears to be in the forum listing. It looks like a flesh light thread!

[G7PSK]

I had this problem on a key fob type control. I soldered a micro tac switch onto the board and cut back the rubber button to accommodate it.

[Fraser]

Thanks,

I think that will be the route I will have to take as well. The swuitches are cheap enough from China.

Fraser

[UPI]

I have tried the paint on silver conductive paint and it only lasted about a year before flaking off on some relatively heavily used industrial keyboards. I have not tried any of the other suggested paint on products listed here.

Here is what I ended up using and they have lasted a couple of years w/o any failures. It sits between the old key surface and the PCB.
http://www.barclayent.com/featureditems/padmate.htm
http://www.ebay.com/itm/Sony-SPP-SS966-Dial-Pad-Repair-Membrane-NOT-ON-OFF-KEY-/170311331019?pt=US_Cordless_Telephones_Handsets&hash=item27a758accb
http://www.amazon.com/Membrane-Panasonic-KX-TGA400B-KX-TGA200B-Cordless/dp/B0019AQT3C

I believe they offer several different sizes and shapes. I would take some measurements and contact them directly to make sure you get the best possible fit.

[duskglow]

I just bought some aluminum foil tape from home depot and stuck it on the little rubber contacts.  Works a treat, as Dave would say.  I can't vouch for wear on heavily used buttons, but for my purposes, it worked absolutely perfectly.

If you've got a lot of travel, get some of that rubber EMI shielding tape.  If it's non-adhesive, try a little superglue (I didn't test this so YMMV).  I tested it, and it would have been a decent alternative if what I had wasn't so thick.

The only downside is you need very little tape, so you get a roll of like 100 feet for $7, and you only end up using an inch of it.