Instrument Design and Function Description R&S CMU
1100.4903.82 3.8 E-5
REARPANEL BOARD2
The REARPANEL BOARD2 is mounted to the right of the integrated
and unscrewable rear panel plate and accommodates the interfaces
S
ERVICE, AUX, AUX4 as well as further spare interfaces. For
connection with MOTHERBOARD1 two 34-pin ribbon cables are used.
The MOTHERBOARD (1100.2352) consists of four individual printed circuit boards: MOTHERBOARD1,
MOTHERBOARD2, FRONTPANEL BOARD and REARPANEL BOARD2.
MOTHERBOARD1
The MOTHERBOARD1 is the central motherboard and serves as
connection between most of the modules. It supplies the modules both
with voltages and control, status and bus signals in various layers (12-
layer multilayer).
The MOTHERBOARD1 accommodates various ISA bus driver devices
for the PCMCIA INTERFACE control as well as protective circuits.
These protective circuits consist of diodes and polyswitches (current-
dependent, self-opening and closing fuses) and protect against
external overvoltages of the interface signals.
MOTHERBOARD1 includes the external interfaces IEEE, LPT, COM1,
COM2, monitor and keyboard.
Nine LEDs indicate the status of the supply voltages and help with
troubleshooting.
On MOTHERBOARD1, a circuit for temperature-dependent instrument
fan control is also implemented:
The individual module temperatures are polled by the FRONT
MODULE CONTROLLER of the R&S CMU. This information is passed
on via the DIGITAL BOARD to the fan control with the aid of a control
signal. The instrument fan is controlled such that an optimum module
temperature is achieved on the one hand and as little noise as possible
is emitted by the fan on the other hand.
MOTHERBOARD2
The MOTHERBOARD2 serves for supply and connection of the
modules located higher at the side, the REFERENCE BOARD and a
further option.
For connection with MOTHERBOARD1 two 50-pin ribbon cables are
used.
FRONTPANEL BOARD
The FRONTPANEL BOARD is located at the front of the instrument
frame and accommodates the external interfaces DATA1, DATA2,
AUX3 and SPEECH. Besides, the six LEDs for the display of the active
RF inputs/outputs are located there.
For connection with MOTHERBOARD1 a 50-pin ribbon cable is used.
REARPANEL BOARD2
The REARPANEL BOARD2 is mounted to the right of the integrated
and unscrewable rear panel plate and accommodates the interfaces
SERVICE, AUX, AUX4 as well as further spare interfaces. For
connection with MOTHERBOARD1 two 34-pin ribbon cables are used.
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