Need help: Restoring HP41C

From: Bryan Blackburn <>
Date: Sat Oct 25 00:31:35 2003

I haven't worked on a large number of calculators, and I am not familiar
with the insides of that one, but if I understand what you are facing:

Use denatured alcohol or other greaseless electronic cleaner and a tooth
brush to thoroughly clean all the copper or plated metal contact areas.
Use Windex or other glass cleaner to clean the conductive strips and LCD
contacts (if any), then carefully dry them with a soft paper towel.
Leave them on the paper towel until you are ready to reinstall them.
(I'm talking about minutes here... not days!) Use a soft pencil eraser
to polish the copper or plated metal contact areas. Be sure to find one
that does not leave a rubbery residue! Pen erasers work great.

Inspect your parts mechanically to be sure that they fit together
tightly, and that they have not become loose from stress or wear. Fix as

Use a dry soft paper towel to dust off and rub the copper or plated
contact areas for a clean and shiny surface. Here comes the tricky part:
wet the strips with a very small amount of Windex on both sides. You
want to create a light film here. Not dripping wet! Then quickly
reassemble the strip and parts that make contact to it before the film
dries. This will create a weak "sticky" bond that will not loosen up easily.

I've done this procedure at least a thousand times (no kidding!) and
unless I did something wrong or the parts were beyond salvation, it
always worked.

Good luck!

> I have an HP41C in pretty decent condition. The problem is that, over
> time, the rubber pads under the flex circuit below the display, and
> the elastomer contacts joining the logic board to the keyboard, seem
> to have deteriorated enough that the thing is wildly intermittent.
> What's the best way to deal with these issues? Would I be better off
> simply replacing the two elastomer strips? If so, where would I get
> them from?
> Thanks much...
Received on Sat Oct 25 2003 - 00:31:35 BST

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