IBM 5155 Manual To Operations page 49

Checking Electrical Connections
1
Set the Power switch on the system unit (and
expansion unit,
if
attached) to Off.
This is the international symbol for On.
o
This is the international symbol for Off.
2
Set the Power switches on all external devices to
Off.
3
Disconnect all non-ffiM devices.
4
Unplug the system unit's (and expansion unit's)
power cord from the wall outlet.
January 1984
Start 20-1