HP 65 Card reader task

[jftman]

Ok.
How does 6v appear in these places?
Given that Vss and Vbs are less than 6v?

In my case regarding the drop when the card has triggered the mtr pin 17,
It drops to 4-5 MV so, not zero but is functioning correctly? Should I be good in that area?

My power supply is designed for Quartz watch current and voltage measurements. There are several current draw and base lines when the watch is in operation

If I connect the Supply and then turn on the calculator, I see a voltage drop but there is the capacity for me to raise the applied voltage up over 4 volts, say 4.25-4.50.

When I do the readings on the sense chip, I don’t see 6v anywhere only the Vbs supplied, and it will drop as required when a card goes in.

But sadly there is 0 volts on pin 1.

Are there any desoldering points to isolate the chip that allow more trouble shooting for the 2.5 volts on pin 1? Perhaps the four red and black on the pcb, but leave the head wires untouched.

To swap out the entire board of course all these would be desoldered. I was trying to reason a way to remove a fault by separating the circuit, to look for restored normal conditions. Like a short, that may exist PAST the sense chip, or a ground that isn’t supposed to be there. (I am a retired telephone company repairman, HA).