IBM 6151 Maintenance And Service Manual page 394

Step 2
1. Set the power switch on the system unit to Off.
2. Exchange the adapter for the fixed-disk and diskette drives.
3. Be sure the power has been off 30 seconds; then set the power
switch on the system unit to On.
4. Wait 2 minutes; then answer the following question.
AJZBl61
IS "23" DISPLAYED IN THE TWO-DIGIT DISPLAY?
NO
Set the power switch on the system unit to Off; then go to
"Step 5" on page 3-9840-5.
YES
Set the power switch on the system unit to Off.
1.
Exchange the system board.
2. Go to "Step 5" on page 3-9840-5.
3-9840-2
Service Manual