HP-65 more on the card reader

[teenix]

(02-09-2019 12:56 PM)albertofenini Wrote:  We did it,
we surrounded the last part of the pcb with some insulating tape on both sides, just leaving the pins out,
but it didn't help ...

It definitely sounds like a mechanical issue.

The card board looks under stress, so it is possible that the inside of the connector holes are not making proper contact with the pins after assembly. Using the scope, you should see steady states on the WA WB lines with the boards working out of the case. Maybe wiggling the card pcb will show up changes that you can track down.

The plating inside these holes can be quite thin and may wear away with many insertions onto the connector pins, causing problems.

You could consider filing the side of the pcb so that it fits around the cpu case, but not so much that you damage the traces.

cheers

Tony