Dean7878
Member
Does the red light come on and stay on when the drive is first turned on? If so then the suspect chip would be in UC2. When you swap the chips the drive should then power up normally. If it does not then you either have 2 faulty 6522(which is not likely) or something else is wrong. If it does power up normally then the 6522 is faulty.
The difference between a faulty UC2 and a faulty UC3 is that when the faulty chip is in UC2 the fault appears when the drive is powered on. When the chip in UC3 is faulty the fault does not appear until a LOAD is attempted. So if one of the 6522s are faulty the symptoms will change. If the symptoms do not change then something else is the problem(or both 6522s are bad but like I said that is unlikely). So swapping the 6522s will either confirm the the 6522 originally in UC2 was faulty or tell you that you should look somewhere else.
The difference between a faulty UC2 and a faulty UC3 is that when the faulty chip is in UC2 the fault appears when the drive is powered on. When the chip in UC3 is faulty the fault does not appear until a LOAD is attempted. So if one of the 6522s are faulty the symptoms will change. If the symptoms do not change then something else is the problem(or both 6522s are bad but like I said that is unlikely). So swapping the 6522s will either confirm the the 6522 originally in UC2 was faulty or tell you that you should look somewhere else.