Power Supplies

A system has one peripheral power supply and up to four or eight CPU/IO modular power supplies. All the power supplies have one green LED and one yellow LED.

The control and status signals of all power supply modules connect to the clock+ board. If the clock+ board LEDs indicate a problem, inspect the LEDs on the power supplies to locate a faulty module, if any.

Peripheral Power Supply (PPS)

The green LED is to the right of the yellow LED on the peripheral power supply. The green LED indicates that the peripheral power supply is operating, but does not necessarily indicate that the DC outputs are within specification.

When the peripheral power supply module yellow LED is lit, a DC power output has malfunctioned or the voltage level is out of specification.

The peripheral power supply produces +5 VDC and +12 VDC current. The current is available for peripherals such as a tape drive and/or CD-ROM drive. In addition, the +5 VDC output of the peripheral power supply is available at the center plane for current sharing with the +5 VDC outputs of the power supply modules.

Power/Cooling Modules (PCMs)

For a PCM at the front of the card cage, the green LED is to the left of the yellow LED. At the back of the card cage, the LED positions are reversed and the green LED is to the right of the yellow LED. See Table 9-3.

When the yellow LED is lit, a fan or a DC output has malfunctioned. Each modular power supply contains two fans and three DC supplies (+3.3 VDC, +5 VDC, and +2 VDC).

The green LED indicates that the DC supplies are operating, but does not guarantee that the DC outputs are within specification.

The PCMs operate in redundant current share mode. If a module fails, the remaining modules may or may not provide enough current to continue system operation. The system's ability to continue operations depends on the total demand for current.