NEC SX Service And Reference Manual page 84

Problem
Serial device does not work
Parallel device does not work
Quick Troubleshooting
Corrective Action
Check if the device driver is installed properly.
Check if the serial device is connected properly.
Check the device drive installation for any IRQ or I/O
address conflict.
Replace the serial device.
Check the I/O controller chip on the main board for any
cold or loose soldering.
Replace the I/O board.
Check all the connections.
Check if the external device is turned on.
Check the device drive installation for any IRQ or
I/O address conflict.
Test another parallel device.
Check I/O controller chip on the main board for
any cold or loosed soldering.
Replace the I/O board.
Troubleshooting 7-3