IBM H Series Installation And Service Manual page 57

Step 1520-4
There is a small dark-colored test switch on the side of the power supply near the
power supply connector. It is a normally off momentary switch. Press and hold this
switch for a few seconds while observing the fans in the power supply and the power
LED on the power supply.
Does the fan in the power supply (not the two external fans) turn on and the
power LED on the power supply change from blinking to solid while you hold
the switch? (When you let go of the switch, the fan will turn off and the LED on
the power supply will change from solid to blinking.)
NO Replace the power supply.
Repeat this step for the second (right) power supply if installed.
Go to "Map 0410: Repair Checkout" in the Diagnostic Information for Mul-
tiple Bus Systems.
YES Repeat this step for the second power supply if installed.
Go to "Step 1520-5" on page 2-24.
Chapter 2. Maintenance Analysis Procedures
2-23