Posts: 1,368
Threads: 212
Joined: Dec 2006
The only thing I can think off is that there is something fishy with Port 4 that renders it adequate to detect the Advantage and Card Reader ROMs but not enough to power the card reader.
I suspect there could be some wear or fraying of the plating on the contacts. I was having weird behaviour in with the card reader in my CV, and on taking the calc apart I noted there was some crimping of the contact along an edge of the male connector for Port 4. I gently flattened the crimping with a thumbnail, gave everything a good clean with 99% isopropanol, and all is fine since.
I don't know if this is your problem specifically, but it seems that the issue is in your fullnut calculator, not in the card reader.
Les
Posts: 210
Threads: 45
Joined: Jan 1970
Did you try BRAND NEW (shouting) batteries in the full nut? It sure sounds like a battery problem to me. As I remember it, this is how I discovered that my full nut took more juice than my half nut. The same used batts would run my reader in my half nut, but not in my full nut. New batts in my full nut did the trick.