Classic Keyboard Contact Strips

[Sanjeev Visvanatha]

I am researching a mushy key repair on a HP-67. From my reading, it sounds like one of the contact strips needs replacing. All of the internals of Classics I have seen show the contact strips intact (e.g. http://home.citycable.ch/pierrefleur/Jac...20Left.JPG)

I could not find any photos of what is hidden when a contact strip is removed. I am trying to see whether I can do this repair, or should I leave it for now.

Does anyone have, or can point me to, a photo of a keyboard assembly with the contact strip removed?

Also, seems like there are small spotwelds that hold the contact strip in place. Are these solely for mechanical joining, or for electrical contact (or both)?

Thank you!

[quantalume]

I'm interested to see what replies you get to this thread. I have a 45 with the same problem--a mushy key. In my case, the contact strip has a crack in the raised area. I tried silver solder to repair, but it did not hold up. I would think that you could replace the metal over one of the contact points, should you be able to find the right material and bend it to the proper radius. A little solder on each side, where the metal isn't stressed as much, should hold it in place.

[Sanjeev Visvanatha]

That may work. I think the easiest is to take the contact strip for an entire row from a donor and replace it.

Maybe I ask my question in a different manner. If I transplant a donor strip in, do I need to solder the strip in place or just some mechanical joining with suitable adhesive is ok in lieu of the original spot welds ?

[Etienne Victoria]

Hi Sanjeev, all,

I use David Smith's procedure here.

This is when I'm sure the metal strip is the culprit.

Personally, I only replace the offending part of the strip, never the full strip if the other keys operate correctly.

When I'm not sure the metal strip is defective, I usually use Steve Loboyko's procedure here..

Etienne