2-12 Installationand Maintenance Volume
Octel 200/300 S.4.1 PB60019−01
PSU Voltages
The AC and DC wiring is prewired to connectors that are automatically engaged when the power
supply is installed. There are no power-supply adjustments. You can check voltages by using a digital
volt meter.
Using the digital volt meter, you can measure the system DC voltages at the voltage test points on
the front edge of the CPU. Refer to the Installation chapter, Octel 200/300 Hardware Installation
section in this volume.
The PSU provides regulated DC voltages as shown in Table 2-1.
Table 2-1 PSU DC Voltages
Name Nominal DC

Voltage

Function

+5 V 5 volts Digital logic power
+5 VC 5volts Analog circuit power
+12 VM 12 volts Fan and disk drive motor power
+12 VC 12 volts Analog circuit power
–12 VC –12 volts Analog circuit power
–5 VC –5 volts Analog circuit power
Power Fail
The PSU provides the system power fail signal. This signal activates if the message server input
voltage drops out of operational range. The power fail signal interrupts the CPU as a warning of loss
of primary power, allowing controlled shutdown.
Octel 200 Power Supply
The Octel 200 PSU is located in slot A10.
The PSU provides a protective fuse for primary power production. This fuse is opened when a
primary overcurrent occurs. The Octel 200 cabinet contains a spare fuse.
The +5-volt PSU is sensed at the center of the motherboard. Each regulated voltage includes
overvoltage and overcurrent protection. The PSU also includes overtemperature protection.
The input voltage is displayed near the power cord socket at the rear of the cabinet and on the PSU.
The AC power filter is built into the PSU.
The Octel 200 floppy disk drive is an integral part of the PSU.Therefore, if either the PSU or floppy
disk drive malfunction, they are both replaced. Refer to The Procedures chapter for details.