Looking for HP-97 LED display

[teenix]

(11-20-2019 12:43 AM)aj04062 Wrote:  Nope. Not the way this display works. I guarantee it. I just repaired a 92 that would not display the negative signs prior to the number and exponent. When I had it apart, I saw under magnification that one of the ribbon cable connections was broken. As I worked on it, I broke a couple others and then entire digits started to drop out....

Once I removed the entire connection, stripped back the insulation (heat not knife) and re-soldered, everything was A-OKAY.

It may be the display, but check this first!

Adam

Actually the display does work in the manner described. Multiplexed common cathode.

The sign digits are common to the one cathode driver output which is why they both worked when you repaired the connection. The sign digit on these calculators only have the [G] segments fitted to the display board, which makes economic sense as all the other segments are not used, unless like me the display gets used for other purposes ;-)

cheers

Tony