Power Subsystem - DEC 4000 AXP Service Manual

6.1.4 Power Subsystem

The power subsystem is a universal supply that is designed to operate in all
countries. Power for the backplane assembly is provided by the centralized power
source. Fixed-media storage devices are powered by local disk converters (LDCs)
included in each storage compartment. The power subsystem has five basic
components:
• Front end unit (FEU) (AC to 48 VDC with power factor correction)
• Power system controller (PSC)
• DC5 DC-DC converter unit—5 V. This unit is capable of providing 150 A.
• DC3 DC-DC converter unit—This unit generates three voltages; 12 V at 4 A,
3.3 V at 20 A and 2.1 V at 10 A (Futurebus+ terminator power).
• Local disk converters (LDCs). The local disk converters generate three
voltages for storage devices (+5, +12 and +5 V SCSI-2/DSSI terminator
voltage).
All of the power supply components (except the LDCs) plug into the system
backplane. An LDC is packaged with each fixed-media storage assembly.
System availability is enhanced via an optional, external uninterruptible power
supply (UPS). The UPS is able to keep the system running in the event of a
power failure.
Figure 6–9 provides a block diagram of the power subsystem components and
their function.
System Configuration and Setup 6–17