Voyager keypad construction

[Zac Bruce]

I'm wondering if there is a difference in the way the keypads were constructed on the original USA made voyagers and later 12c/15c LE? I have a very worn out USA 12c and the keys feel a bit "squishy" and maybe have less travel than the newer models. The bottom half of the enter key does not move at all or give any tactile feedback when pressed but does register. The newer keys have a much more tactile/clicky feel and sound, which I really like. I'm wondering if it's just that my 12c is very worn out. I have the chance to buy a "new" USA made 12C but worry that I might not like the keypad.

Thanks all.

[Zac Bruce]

I tried taking the back off the calculator today.
Two thin, long springs fell out. Anyone have any ideas where they have come from?
It also appears that you can't access the front of the keypad, there are plastic posts with little nubs holding the board in place. Correct me if I'm wrong.
When I reassembled two vertical rows of keys weren't working but disassembled and cleaned the board and now it's all OK. Doesn't seem to be affect the calculator not having those springs in there, whatever they were!
A bit of gunk must have been moved when pulling it apart of putting it together, now one of the keys has a bit of a click..or more like a pop when pressing it, so I'm wondering if there is some kind of membrane behind the keys and maybe it's all full of rubbish that is affecting the feel and sound of the keys.

[mfleming]

The springs just serve to ground the metal plate on the back so that it shields against radiated RF energy. Nothing to worry about, I think they stand in a couple of holes along the sides. The nubs you mention are heat stakes, plastic posts coming up from the front of the case. During assembly the pcb is placed over the posts and then heating elements are applied to the top of the posts. That forms the nubs which hold things in place. This is obviously a one-way assembly technique!

Search the forum posts or articles for more information. It's best to use an external search engine like google or bing and add the site:hpmuseum.org qualifier to restrict the search. The forum search engine leaves a little to be desired.

Good luck tinkering,
~Mark