Help with HP-67

[teenix]

(06-06-2019 01:34 PM)twoweims Wrote:  I recently acquired a non-working HP-67.
It appears that there is a short circuit between Vbsw and ground.

I have isolated the card reader and the logic board and tried to power the keyboard/display board alone and the fault persists.

Check for obvious shorts on the key/display circuit board.

Look closely at the wiring that is soldered to the top of the board. These are mounted really close together and can easily short if the wires are frayed.

Same for the card reader board.

Try isolating the power wires to the card reader. The problem could also be the sense chip as it has direct connections to the battery.

cheers

Tony