Instructions for model 505

1. Is the reference code 1xxx 2631?
   • No: Continue with the next step.
   • Yes: The 1.5V voltage regulator, which is part of the system backplane, is the failing item. Replace the system backplane (see Locations -- model 505). This ends the procedure.
2. Is the reference code 1xxx 2632?
   • No: Continue with the next step.
   • Yes: The 2.5V voltage regulator, which is part of the system backplane, is the failing item. Replace the system backplane (see Locations -- model 505). This ends the procedure.
3. Is the reference code 1xxx 2636 or 2637?
   • No: Return to Starting a Service Call. This ends the procedure.
   • Yes: Continue with the next step.
4. The 1.3V voltage regulator is the failing item and needs to be replaced (see Locations -- model 505). If you have a 2-way processor, you will have two 1.3V voltage regulators--both of which will need to be replaced.

   Does the problem persist?

   • No: This ends the procedure.
   • Yes: Replace the system backplane (see Locations -- model 505). This ends the procedure.