SA7x Technical Description
2.5 SA7x Power Supply
2.5 SA7x Power Supply
The power supply slides into the chassis between tabs on its upper case and a
ridge on its lower case, as shown in Figure 2–6. An interface connector on the
power supply plugs into a self-aligning connector inside the enclosure frame.
Mounting screws on the rear panel of the power supply secure it in the frame of
the enclosure.
The rear panel of the power supply contains cutouts for exiting cooling air from
the enclosure and for access to the Master On/Off switch, Line Voltage connector,
and Line Voltage Selector switch. These components are physically part of the
power supply circuit board.
An enclosure Fault indicator is located on the power supply. This indicator is
visible, when lit, through holes in the upper-rear panel of the power supply.
The power supply provides operating voltages for all components of the SA7x
enclosure, including the fan assembly. The outputs of the power supply include:
• Four +5.1 Vdc outputs at 3.9 amps maximum each
• Four +12.1 Vdc outputs at 5.4 amps maximum, 3.6 amps steady state each
• One +12.6 Vdc output at 2.0 amps maximum, 1.8 amps steady state
The supply features 120 Vac (60 Hz) or 240 Vac (50 Hz) single-phase, switch-
selectable, input line voltage, a fast transient response on the +12.1 Vdc outputs,
and overcurrent and overvoltage protection on all outputs. Each of the regulated
voltages supplied to the disk drives is independently controlled by logic signals,
and each of the four regulators provides a status signal output to show normal
operating voltages at the drive power switches. The power supply also monitors
enclosure temperature and fan rotation. The power supply automatically shuts
down when it detects an overtemperature condition.
Total average load power delivered from the power supply is 277 watts; full rated
load output power is 384 watts.
Line voltage is selected at 120 Vac (60 Hz) or 240 Vac (50 Hz) with the Line
Voltage Selector switch. This switch is located behind the rear panel of the power
supply and is manually set during installation or when the line source is changed.
See Figure 2–6.
A line voltage fuse is hard-wired to the supply circuit board. If this fuse blows,
the power supply must be replaced as a unit. There is no need to change the fuse
when switching between line voltages.
2–10 SA7x Technical Description