Instructions for model 520

1. Is the reference code 1xxx 2630?
   • No: Continue with the next step.
   • Yes: The voltage regulator for 1.2V is the failing item and needs to be replaced (see Locations -- Model 520 to locate and replace the regulator).This ends the procedure.
2. Is the reference code 1xxx 2631?
   • No: Continue with the next step.
   • Yes: The voltage regulator for 1.5V is the failing item and needs to be replaced (see Locations -- Model 520 to locate and replace the regulator). This ends the procedure.
3. Is the reference code 1xxx 2632?
   • No: Return to the Starting a Service Call. This ends the procedure.
   • Yes: The voltage regulator for 2.5V is the failing item and needs to be replaced (see Locations -- Model 520 to locate and replace the regulator). This ends the procedure.
4. Is the reference code 1xxx 2636 or 2637?
   • No: Return to the Starting a Service Call. This ends the procedure.
   • Yes: The 1.2V voltage regulator is the failing item and needs to be replaced (see Locations -- Model 520. If you have a 2-way processor, you will have two 1.2V voltage regulators, both of which will need to be replaced.
5. Does the problem persist?
   • No: This ends the procedure.
   • Yes: Replace the system backplane (see Locations -- Model 520). This ends the procedure.