IBM 6150 Hardware Maintenance Manual page 287

Step 6
1. Exchange the processor board in slot A.
2. Be sure the power has been off 30 seconds, then set the power switch
on the system unit to On.
3. Wait 2 minutes, then answer the following question.
IS "23" DISPLAYED IN THE TWO-DIGIT DISPLAY?
YES Set the power switch on the system unit to Off, then go to "Step
8" on page 3-9810-8.
NO Set the power switch on the system unit to Off.
1. Remove the processor board from slot A.
2. Exchange the system board.
3. Go to "Step 8" on page 3-9810-8.
3-9810-6 Service Manual