IBM 3270 Maintenance Manual page 409

Remove the adapters one at a time, as described:
1.
Set the Power switch on the system unit (and
expansion unit, if attached) to Off.
2. Remove one adapter (in the following order).
• Option adapters: .
- Personal Computer options
- Printer
- Fixed Disk
• Distributed Funtion Communications
Adapter (2801 error)
• Diskette Adapter (601 error)
• Display Adapter (one long and two short
beeps)
• Keyboard/Timer Adapter (no display, two
beeps)
Note: The above error codes result from
removing the adapters.
3. Set the Power switch(es) to On and see if the
failure symptom remains.
4. Continue to remove one adapter at a time
until the failure symptom disappears or until
you have removed all the adapters.
CONTINUE
3-9999-4 Maintenance Information