HP 330 Service Information Manual page 87

Motherboard
Introduction
Each unit has a different motherboard. This is necessary for the different connectors and shapes
used for the computer and the two expanders. Refer to Figure 3-12 for the differences.
Virtually all assernblies connect directly or indirectly to the motherboard. It has connectors for
other asseillblies to interface with each other. Test points for power supply voltages are marked
on the board.
Functions
Power is connected frorn the motherboard to the optional DIO backplane via a ribbon cable. In
the computer, boards in the system slots are powered directly from the motherboard through
two system slot connectors. Voltage test points are on the back of the motherboard and are
accessible from behind the front panel.
Two fans are connected to motherboard power connections. The large fan is tied to the
+
12
and ground. The small fan is tied between +5 and -12 V dc. Wires from the front-panel LED
are connected to the
+
12 and -12 V dc voltages on the motherboard.
The top of the lllotherboard is a large connector to interface with expanders. Data, control,
and status signals are ported through this connector. There are no active components on the
lllOtherboard. Both the computer's and expander's motherboard have the same part number.
Functional Description
71