HP25C sad story, need opinions

[husmus]

A friend gave me a challenged HP25C. It had corrosion and heat exposure that apparently damaged the keyboard. The keys x,1,2,3,6,R/S don't register well, or ever in the case of the 6. Otherwise it's in great shape so I'm contemplating what to do? Find a more common HP25 keyboard from a donor calculator? Leave it alone and display it as-is, a victim of the design and lack of care? Other options? Thanks.

[John Garza (3665)]

Definitely give it a shot on the repairs.
Sometimes a little Deoxit and scrubbing with fine stranded wire through the holes does wonders.

-J

[35/45/55/80/70/65/67/67T/97/97S/91/92/21/22/27/25C/29C/19C/10/
31E/32E/33C/34C/37E/38C/41CX/71B/28S/19BII/12C/15C/33S/35S/32SII/
48GX/50G/Prime/DM42]

[spikeofax]

Difficult to say without slides. You may also have to clean the contact points beneath the keys. Much is possible with patience and time, though. Andrew

[John Garza (3665)]

BTW, I just used the procedure I described above to resurrect an HP-21. Battery corrosion migrated to the keyboard. 100% DeOxit in the holes. Set for 15 mins. Scrub with stranded copper wire in the hole rotating as much as possible to get around the inside of the contact area. Flush with 5% DeOxit spray, then compressed air. I now have an excellent HP-21 for $33 plus a half hour of my time.

-J

[35/45/55/80/70/65/67/67T/97/97S/91/92/21/22/27/25C/29C/19C/10/
31E/32E/33C/34C/37E/38C/41CX/71B/28S/19BII/12C/15C/33S/35S/32SII/
48GX/50G/Prime/DM42]

[Hiwi]

Not all HP25C have these holes, the early versions had none.
The only way to get these keys working is to remove the heads of the plastic welded studs.
Take off the pcp clean everything and glue the pcb back.
Ralf

[John Garza (3665)]

Yes done that too - slice off the tops of the heat stakes. Tedious but can be done.
Also remember to service (clean/lube) the slide switches while you're in there!

-J

[Maximilian Hohmann]

Hello!

(04-04-2023 12:59 PM)John Garza (3665) Wrote:  Yes done that too

Yes, but in my experience the calculaotr will never be as before after this kind of "surgery". Personally I will not do that again, the result is unpredictable and you never know how long it is going to last.
Non-working woodstocks are in plenty supply for little money and most of them have good keyboards. Combine two non-working calculators into one, maybe using some parts of Panamatik, and you will get a perfect result!

Regards
Max