IBM 6151 Maintenance And Service Manual page 72

Step 13
Look at the operator panel.
AJZB159
IS THE POWER-ON INDICATOR ON?
YES Go to "Step 17" on page 3-0010-18.
NO
Be sure that both ends of the external power cable to the
system unit are connected.
If you find a problem, go to the step where you were
instructed to set the system unit power switch to On and
try the procedure again.
If you do not find a problem, go to "Power Supply PIC
8800" on page 3-8800-1.
3-0010-14 Service Manual