Step 2. Run The Power On Self-Test (Post) - IBM 3270 Hardware User's Manual

Step 2. Run the Power On
Self-Test (POST)
1.
If your display has an On/Off (I/O) switch
turn it On (\).
2. If your display has a contrast or brightness
control, make sure they are turned clockwise
as far as they turn (full intensity).
3.
Make sure the On/Off (I/O) switch for the
system unit (and expansion unit, if attached)
is Off (0).
4.
If there is a diskette in drive
A,
remove it.
5.
Get the Diagnostic diskette from the back of
this binder.
6. Insert the Diagnostic diskette in drive A.
7. Push down the lever on drive A.
8. If you have an expansion unit attached, turn
it On (\).
If you do not turn on the expansion unit first,
you will get an error message.
Chapter 5. Locating Problems with Your PC Units 5-5