IBM 3270 Maintenance Manual page 345

1.
Set the Power switch on the system unit to
Off.
CAUTION
Do not connect or disconnect the coaxial
cable during an electrical storm.
2. Disconnect the coaxial cable from the system
unit.
3. Check the coaxial cable connector at the
system unit for the appropriate resistance as
shown in the diagram.
CONTINUE
3-2800-10 Maintenance Information
Resistance should be
less than 1 ohm.