IBM 5155 Manual To Operations page 181

10
Set the display's Power control to Off.
11
Disconnect the display's signal cable from the
system unit or expansion unit.
g·pin Signal
Connector on Color/Graphics
Monitor Adapter
12
Set the Power control on the display to On.
13
Is the screen white?
YES -
Have the unit that the display was
attached to serviced.
NO - Have the display serviced.
14
While watching the screen, set the Power switch
on the expansion unit
(if
attached) to On. Then
set the system unit's Power switch to On.
January
1984
Test 9000-5