I am repairing a level seven mpu board that is locked up.
I have repaired these before and have been lucky til now.
I am using a test chip that counts up the error codes then flashes twice and goes out.
This board flashes the dreded 8 error code after liting all 9.
I could not find anything wrong with the memory protect circuit so I changed every chip in it one at a time.
Same problem.
The picture of the mpu in the book shows all the chips in this circuit.
Has anyone out there had experience repairing this problem ?
I have repaired these before and have been lucky til now.
I am using a test chip that counts up the error codes then flashes twice and goes out.
This board flashes the dreded 8 error code after liting all 9.
I could not find anything wrong with the memory protect circuit so I changed every chip in it one at a time.
Same problem.
The picture of the mpu in the book shows all the chips in this circuit.
Has anyone out there had experience repairing this problem ?
