IBM 6151 Maintenance And Service Manual page 333

Step 3
1. Set the power switch on the system unit to Off.
2. Turn the Brightness control fully clockwise.
3. Wait 1 minute; then answer the following question.
AJZBl96
IS THE DISPLAY SCREEN COMPLETELY LIGHTED?
NO
Record SRN 26-580; then go to "Step 7" on page 3-5800-7.
YES
Continue on the next page.
(6(88) Problem Isolation Charts 3-5800-3