Non clicky HP41 key

[Geoff Quickfall]

The book the book the book, soon. :-)

Your 41c:

-LCD: cleaning, best way, desolder at the PCA side, then damp cotton cloth to clean underside of lens and the top side of the LCD. Place bracket and panel back, solder the far left or right contact in place, observe alignment-adjust and when satisfied solder the other far right or left contact thus securing the alignment at the opposite ends. Check again!!! Then solder remaining points. I use a three aa battery solder iron with fine point, very hot but for a short period and use flux.

-keys: fixing domes involves removing all the heat stake tops (NOT ADVISED FOR THE FAINT HEARTED) sorry for the shouting. The hard part is leaving enough of the heat stake behind to remelt a cap. The REALLY hard part is soldering a replacement dome from a donor into place. Repairing the dome with solder has been tried but will fatigue very quickly. My suggestion is to live with it if still contacts. I know, not satisfying but what can you do? Getting a bouncing key repaired involves a drop of deoxit gold introduced into the tiny 'pore' associated with the offending key and then simply; pressing the key repeatedly. Deoxit actively restores the contact and removes corrosion, then protects the contact. It will fix the continuity problem but will not fix a cracked dome; which is the reason for no click.

-PCB/PCA Board: the problem with the nuts as they were self tapping. Re screwing them may cause the post to be stripped. HP when repairing them would substitute a smaller diameter nut. Typically this repair was a one off. Along comes you and I. We will remove and replace multiple times troubleshooting and perfecting. So here is a repair is the nuts become cross threaded and stripped.

This is a tall keys to 41c conversion with stripped PCA threads for the nuts. Scroll down the posting to see how I substituted the nuts with silicon tubing, the same tubing used for card reader repairs:

http://www.hpmuseum.org/cgi-sys/cgiwrap/...ead=186130

Scroll down to see keyboard heat stake and 'pore' pictures:

http://www.hpmuseum.org/cgi-sys/cgiwrap/...869#217869

Deoxit gold, google it and purchase a small tube (inch and a half long). EBay search and you will see deoxit in packets of three. I have restored a Grundig 4500 as well a a Philips philletta vintage 50's tube radios and the other two application tubes are perfect for these volume control and tube contacts.

Check out the search function as any problem that arises, chances are they have been addressed.

Geoff