Posts: 182
Threads: 21
Joined: Apr 2006
Adam,
the spare part is ok, but what do you see in the display when you switch on the calculator? If nothing appear you have some trouble with the switch of the reader, maybe the motor control switch is touching the keyboard PCB.
HTH
Ignazio
Posts: 883
Threads: 17
Joined: Feb 2006
While it is *typically* the ACT, don't assume that is the only cause with the 67 - as anything corrupting the data bus could do that. You can leave the card reader board disconnected while troubleshooting.
What I found was that you can usually go down in function level... i.e. a 67 ACT works in a 25 but I have seen inconsistencies going the other way as you did. FWIW, the 21 ACT is unique and will not work up model at all as it lacks the I/O signal.
Eric Smith might have some more detail as he has cataloged most the processors by part number.