HP-71B ver 2CCCC - Anyone ever have one?

[MikeSD]

(12-20-2023 08:05 PM)Dave Frederickson Wrote:  Hi Mike,

First of all, the top half only has the display chips and CPU. The ROM and RAM are on the bottom half with the serial number.

Answers:
1. My info shows versions 2CCCC on units with date codes 2713A to 2745A but the range could be wider.
2. Just the bottom half.
3. N/A
4. Removing all the solder can be tricky. Then your left with the issue of dissimilar metal corrosion. I'd recommend against it.
5. Using an ohm meter and referring to the Hardware IDS it shouldn't be too much trouble to figure out.

Dave

Thanks for the info. I should be able to find the correct bottom half, that has 2CCCC in it.

I also have a short 24 pin flex cable that has almost the exact spacing. I can get 4 flat traces soldered to 4 contacts without touching the other pads. Every 5th position won't line up. So, I'll just snip off every 5th trace. And use the four 4 trace sections and remove the 5th and by splitting it up the cable a bit, have enough flexibility to attach the other traces. But it might be nicer looking if I just split the flex circuit into 4 distinct flex circuits.

0 0 0 0 X 0 0 0 0 X 0 0 0 0 X 0 0 0 0 X X X X X

0 - Conected trace
X - Discarded trace

Thanks, if it's successful, I'll post a picture.