NEC NC1600C Service Manual page 119

CPU Fail (Mem)
CPU Fail (IO-C)
CPU Fail (IO-A)
Is there any abnormality between the CPU PWB
and the PJDIV PWB, such as drawing out of the
connector?
Yes
Is it possible to solve the problem through NEC
software rewriting?
Yes
Replace the CPU PWB.
"Confidential, Do Not Duplicate without written authorization from NEC."
TROUBLESHOOTING
No
No
4-24
Adjust the faulty spots.
Normal operation.