Threaded Mode | Linear Mode

teenix · (This post was last modified: 02-12-2020 12:26 AM by teenix.)

(02-11-2020 11:51 PM)albertofenini Wrote: The scale is the same for all of the pictures
The first one is Disp0, pin 1 of the logic board
Would this explain the segment always lit and the one always missing in this unit ?
How could we fix it ?
Thanks so much !
BTW This is this a good candidate for a replacement of your ?

Take the CPU board out and power it up with 3.75V. Measure that pin again. It now has no electrical load attached, so if it is the same then the ARC in the hybrid is faulty or there might be a problem with the PCB trace from the hybrid to the hole that the keyboard connector mates with.

If it now looks the same amplitude as the others, then there is a fault on the keyboard.

Just as an addendum, I think disp0 on the HP65 Tony Duell's circuit corresponds to Data C on the HP diagrams and disp2 corresponds to Data A.

cheers

Tony