Before going any further, I trust that you have cleaned and inspected the connector? It's not a dirty pin or a dry solder joint?
I'm wondering if one of the control signals is marginal.
If one or more data lines or one or more lower address lines was continuously faulty, then the fault would be more consistent. And as you have changed both IC71 and IC72, it's unlikely a replacement part would have the same fault.
Is the signal on IC72 pin 19 good?
Mark
I'm wondering if one of the control signals is marginal.
If one or more data lines or one or more lower address lines was continuously faulty, then the fault would be more consistent. And as you have changed both IC71 and IC72, it's unlikely a replacement part would have the same fault.
Is the signal on IC72 pin 19 good?
Mark
Statistics: Posted by 1024MAK — Mon May 19, 2025 10:19 pm