|Re: HP-67 keyboard restoration|
Message #4 Posted by Jose Poyan on 14 Apr 2010, 4:13 p.m.,
in response to message #3 by Pierre Brial
Which strips were broken on your hp45? The bent strips or the contact strips on the pcb?
As I said I dind't open my hp67, but I can tell you about a repair I did on my HP34c last week.
I bought from ebay silver contact paint that comes in small 3 grams glass tubes, for £4. I used this paint to cover the metalic strips on the pcb. I used it too to paint the contact strip on the membrane that was broken for the key "1" (my version of hp34c uses a plastic membrane for the keyboard, with bubbles on the keys and metalic strips for contacts)
This failed becouse the bubbles deform when pressed and the paint is not elastic.
Then I bought cupper tape, that are used in plants to avoid insect, and you can get from ebay for £3, and it's the same as the aluminium tape but cupper one.
I cut a very small square. The glued side is not conductive, so I turned it over almost from the middle to make a doble conductive tape and I left a thin strip with glue. I put it under the membrane, and it worked. Most notable I didnt loose the elasticity of key "1", it feels exactly the same.
Yes, I scratched a little with my screw driver on the pcb, but it didnt mind since I completed the scuffs with Silver paint which proved to be very conductive.
I suggest you to use Silver paint for the contacts. Please let me know if you find the bent strips bronken when you open your hp67.