+- HP Forums (https://www.hpmuseum.org/forum)
+-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html)
+--- Forum: General Forum (/forum-4.html)
+--- Thread: HP-41C: The "1" key fails sometimes (weak contact). (/thread-17463.html)
HP-41C: The "1" key fails sometimes (weak contact). - Danito-Danone - 09-11-2021 09:31 PM
Hi all, The "1" key of my HP-41C fails sometimes (weak contact). Question: Is safe... -> Can I open the "sealed" keyboard? Many thanks, D-D
RE: HP-41C: The "1" key fails sometimes (weak contact). - Milo - 09-11-2021 09:44 PM
The keyboard is attached with a lot of melted poles and I wonder if it is possible to reattach them. I don't think so.
RE: HP-41C: The "1" key fails sometimes (weak contact). - g8241CV - 09-11-2021 11:40 PM
Suggest you search on De-Oxit cleaner. As a warning/hint research broken posts (a hazard in opening a HP-41), and be careful with ESD controls. No expert, but have learned much here via the forum search, and have had good luck. Need to look up threads on opening up an HP-41.
Example link to get you going on the subject:
https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv021.cgi?read=217869
No affiliation, but a one-stop info source to consider:
https://www.amazon.com/HP41-Repair-beginners-calculator-Calculator-ebook/dp/B08JJDW6HM
RE: HP-41C: The "1" key fails sometimes (weak contact). - BillBee - 09-13-2021 11:31 AM
Hi There,
Its a pretty straight forward job on the surface. 4 screws are under the feet, remove the rear cover and you will see the processor board and the main keyboard/display pcb. You will see tiny holes in the main pcb which are located behind the keys. The method (IIRC by a guru from here Randy) was to put a drop of DeOxit over/in the hole and use a single strand of wire (stiff like from a wire brush) to go in the hole and gently rub the interior contact surface. I like to repeat it a few times while working the button.
Only issue you may run into is how the processor board is attached. The older Cs will have nuts holding them to the lower posts, newer ones should just lift off. You might have to remove that board to see the hole for the "one" key.
When done, reassemble and test.
You might find stuff you need to fix as you go but hopefully not. They are not that fragile IMO as long as you don't force things.
Take Care!
Bill
RE: HP-41C: The "1" key fails sometimes (weak contact). - Dave Britten - 09-13-2021 02:53 PM
Cleaning the key contact with a little Deoxit is no sweat - I've done it plenty of times myself, with great results. HOWEVER, the main risks in opening a 41 are cracking the screw posts (a few of which I've also had to repair), or dislodging/damaging the zebra connectors (had to clean the connectors pretty aggressively to get my 41CV working again after I opened it, but it's fine now).
RE: HP-41C: The "1" key fails sometimes (weak contact). - Danito-Danone - 09-13-2021 10:11 PM
Thanks a lot, fellows! I'll try to fix this issue soon. D-D.
RE: HP-41C: The "1" key fails sometimes (weak contact). - Geoff Quickfall - 09-15-2021 02:11 AM
The idea here is the same as the field of medicine: do no harm! Or barring that do the least amount of harm to get the job done.
So deoxit into one of the pores on the PCA before you rip open the heat stakes.