HP-65 1333A02242 display missing all the decimal dots

[teenix]

(11-09-2020 09:30 AM)AndiGer Wrote:  Maybe this link can help? See the last entry. It is posted for the HP-67 but maybe also hits the situation in the HP-65?
Good luck!

Good link.

However, the display drivers in the 65 are a more complicated concept to the 67. The 65 anode driver consists of a decoder to sort out the 5 input display lines to 7 segment outputs and additional processing for the decimal point and then energizes the coils, and with the help of the cathode driver, discharge into the LEDs. It also has synchronizing circuitry to the hybrid ARC chip. A driver transistor in the mentioned 67 configuration would not work in this case.

cheers

Tony