Supervisor Board - HP 9030 Service Manual

Theory of Operation
2-7
Supervisor Board
The supervisor board contains most of the monitoring, control, and fault-indicating circuitry for the
power supply assembly.
The overvoltage and undervoltage monitor checks the voltage outputs of all secondary board
power supplies. The monitor also checks the
+
5V output and the peak power monitor from the
primary board. If a fault is detected, the pulse width modulators are disabled, the shutdown
sequence is enabled, and the appropriate LEOs are lit.
Temperature monitors check the power supply assembly thermistor, described in preceding para-
graphs, and the processor stack thermistor. When the processor stack temperature exceeds 100°C
or the power supply temperature exceeds 97°C, this board generates the power fail warning
(NPFW) signal and initiates the shutdown sequence.
A
+
10V reference supply provides the voltage condition references for over and under voltage
monitoring and temperature sensing. This supply is enabled by the
+
16V bias supply from the
primary board.
The fan control circuitry provides a constant -10V to the
110
card cage fan (FANIon Figure 2-3)
whenever power is on . . This fan is not stepped and never changes speed. The fan control circuitry
also provides -10V (low speed) to the power supply assembly fan (FANP) and processor stack fan
(FANF) as long as the power supply assembly temperature does not exceed 39°C. When the power
supply assembly thermistor detects between 39°C and 51°C, the fan control circuitry provides
-12V (medium speed) to the two fans. Between 51°C and 97°C, the fans are prOVided with -14V
(high speed). The fan high signal (NFANHI) is also sent to the processor which sends a message to
the user, indicating that the computer is performing maximum cooling and that a further tempera-
ture increase could result in shutdown.
If either the 110
door or processor stack door is opened while the power supply assembly is
operating, the shutdown sequence is initiated.
The start-up/shutdown sequence control circuitry is controlled by a 30-KHz clock. The signals
generated by this circuitry are defined as follows:
PPON - Primary Power On; all outputs in specification.
NPV - Not Power Valid; this signal is the inverse of PPON, and therefore signifies "not
all outputs in specification".
NPI -- Not Pop In; used to reset the processor stack.
NSYSPU -- Not System Pop Unsynchronized; used with NPI to cause the processor stack to
perform a self-test.