HP31E Missing Pin

[PANAMATIK]

(03-14-2021 10:47 AM)teenix Wrote:  Hi all,

I just had my first experience with the innards of the HP-3x series and I'm sure as others would have found they seem built more around cost than maintenance.

The repaired IC pin did not work when I connected to my power supply - about 2.7V. After removing the inner plastic frame and looking around, the ribbon cable has corroded and split which seems a common fault.

I'll try a fix, but it could be a candidate for Bernhard's repair kit if the owner is interested.

cheers

Tony

There is a secret of this chips with missing Pin 8. How could this pin got lost in a soldered version. if it was already broken before the soldering, the calc never could have been released in the wild. And adding the pin did not repair the calc in both cases, mine and yours. Perhaps we don't understand what's going on. Is this pin intentionally missing? Is this a dummy chip, which should not be powered up? The HP-31E does only need two ICs, one ROM one RAM. But why was it assembled at all?

Of course the SPICE LP could repair this calc.

Bernhard