HP65 Loosy keyboard

[isanchez]

Dear all,

I have seen a previous post regarding the "feeling" of some HP65 keys. This is usually because the metallic flex breaks due to the use. The only solution is to replace this flex, which is not very easy...

In my case, the problem is that the six inner screws that fix the keyboard in place do not press the part properly. This is caused, probably, by the plastic holes fatigue. This makes the keyboard sounds like a rattle, the keys sink a little, and an there's an overall lose of that "click".
I am not sure how to fix this (at least I do not want to worsen it). I am not sure if longer screws would work (the actual ones are quite long). On the other side, I have tried to use some teflon ribbon to thicker the actual screws with not so much success (apparently the teflon does not pass the first hole, so it kepts there avoiding its mission...
I am open to suggestions (I have seen this pathology in some classic calculators, in combination with the flex breakage for some of the keys).

Thanks in advance and kind regards

Ignacio

[John Garza (3665)]

Hi Ignacio,

I had a similar problem with a 67 back in the 90's. I tried a variety of approaches, but the one that worked best was to simply fill the holes with new melted plastic and let it harden. Then drill out new holes using progressively larger drill bits until the screws can be fitted.

-J

[teenix]

I've seen examples of JB Weld being used to help rethread by putting some in the screw hole and a light coating of vaseline on the screw, then screwing it in and leaving it there until the glue hardens. You should then be able to remove the screw. I would test this first before trying on the 65 though.

Adding bulk to the screw threads, like teflon, might lead to a crack in the screw hole in the aged plastic.

Trying to plug the holes with glue or similar then re-drilling might also work, but the holes need to be drilled in the proper alignment. Also, you have to make sure there are no air bubbles trapped in the blind holes. Poking thin wire into the holes while adding the glue may fix this. The thicker the glue, the more likely this will happen. You will also have to remove the excess liquid glue from the mating surface before it sets so that everything sits properly on re-assembly.

Are the threads stripped, ie. the screws keep turning without tightening or is it that the black plastic frame does not seat properly. Sometimes this happens if the frame is not aligned properly and rocks back and forth like something is under it. If so, tightening the screws deforms the plastic and can also cause problems with the card reader.

cheers

Tony

[Roland57]

I did several successful repairs in the past using this method:

rip off the insulation of an appropriate wire. Appropriate means its diameter is far less than the hole you like to fill. Cut the insulation to size (a little longer than the depth of the hole). Stick it into the hole, cut off the excess part. Turn the screw into the now tighter hole. If the screw still has no grip, use two or more pieces of insulation or a thicker version.

The advantage of this method: it is reversible.

Roland

[isanchez]

Thanks you all, I find you are proposing very clever ideas. I shall start with the last one, as it is reversible ....and I would never thought about it!!

Thanks an kind regards

Ignacio