IBM 3270 Maintenance Manual page 585

16. Turn the screw until the speed shown on the
screen is within the required specifications.
17. Set the Power switch on the system unit (and
expansion unit, if attached) to Off.
18. Set all external Power switches to off
(printer, Display, and others).
19. Unplug the power cords of the system unit
(and expansion unit) from the
outlet~
20. Disconnect all cables from the rear of the
system unit.
21. Install the cover of the system unit (5-100-3).
22. Connect all cables.
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