Retooling a HP 12C
#1

I was just taking a look at some of Eric Smith's internal photos of a 12C:
http://gallery.brouhaha.com/romsucker-voyager

Looks like it may be pretty easy to do a new PCB for this and turn it back into a 15C, or whatever you like.

How hard and expensive would it be to get new blank keytops molded I wonder...

Anyone considered it?

Dave.

#2

Easier said than done. For one thing, the heat stakes are designed to be a one-way fastening process. The blank keytops are already there, just strip off the silk-screening and you'll have a fresh canvas.

All around it's a far from cost-effective process. You're investing $70 for plastic and an LCD that's worth less than 1/10 as much.

#3

Quote:
Easier said than done. For one thing, the heat stakes are designed to be a one-way fastening process.

You only need them to be removed and rejoined once.

Quote:
The blank keytops are already there, just strip off the silk-screening and you'll have a fresh canvas.

Ok, nice.

Quote:
All around it's a far from cost-effective process. You're investing $70 for plastic and an LCD that's worth less than 1/10 as much.

Cost effectiveness has nothing to do with a fun DIY project.

Yes, the LCD is limited, but that potentially makes it easier to interface using a new DIY PCB, as opposed to the dot matrix used in the new 35S for example, that looks rather more difficult. Perhaps the LCD could be replaced as well...

Dave.

#4

I can envisage a forthcoming price rise in non-working Voyager models :-)


- Pauli

#5

If you're able to reuse the LCD, even low-volume production could be relatively cheap. You should be able to get away with a simple 2-layer PCB, it should only need an inexpensive MCU. As long as the PCB is being changed I think it would be worthwhile to put in some better tactile domes.

#6

Quote:
As long as the PCB is being changed I think it would be worthwhile to put in some better tactile domes.

Do recent 12Cs have worse domes than the earlier ones? Do you have any specific dome vendor or part number in mind?

#7

Actually, I've even found old voyagers that don't feel quite as good as others. The company I chose for OpenRPN is Snaptron. For a double sided PCB domes from their "P" series are ideal (rated to 5M cycles, and can be ordered with gold plating).

#8

Quote:
I've even found old voyagers that don't feel quite as good as others.

That's not surprising, if one has had more wear than another. The life of the domes isn't n cycles without no change and then sudden abrupt failure. They degrade (wear) with use.

The question is how much variability was there when the Voyagers were new, and I think the answer is "not much". I used perhaps two dozen Voyagers before 1986, and there were no noticeable differences in key feel at the time.

But is the performance of the domes in a new 12C (not 12c Platinum) significantly different than the original dome performance of a 12C made in the early 1980s? If they have been redesigned using different domes (or no metal domes), they could be noticeably different. I haven't used any new 12Cs in a long time. The 12c Platinum keyboard does not feel quite the same to me as the original Voyagers.

Quote:
The company I chose for OpenRPN is Snaptron.

Based on experience, or just on the published specifications? Most if not all of the dome vendors offer similar specifications. As it happens, I was considering Snaptron as well, though I haven't yet evaluated their products.



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