R&S FSP Instrument Design and Function Description
1164.4556.82 3.11 E-1
Power Supply Module
The power supply module provides all currents necessary for the operation of the R&S FSP. It can be
switched off by means of the power switch on the rear panel.
The power supply module is a primary clocked switching power supply with Power Factor Correction
(PFC) and Standby circuit (+12 V Standby).On the secondary side, it generates DC voltages (+3.3 V;
+5.2 V; +6 V; +8 V; +12 V; +12 VFAN; +12 V Standby; +28 V; -12 V).
The control signal STANDBY/ON controlled by the front module controller (depending on the
STANDBY/ON key on the front of the instrument frame) activates the power supply. In standby
operation, it only supplies the 12 V-standby voltage for the crystal oscillator and the LED STANDBY on
the front panel.
The secondary voltages are open-circuit-proof and short-circuit-proof with respect to ground and each
other.
An overtemperature protective circuit is additionally installed to prevent overheating. This status is taken
to the front module controller via a status signal (OT).
Fuses
Two fuses are also fitted in the power supply as a means of fire protection.
Note: These fuses are not accessible to the user from outside and are only blown in the case of a
serious fault of the power supply (servicing required!).
Motherboard
The motherboard generates the –6V supply for the analog boards with an integrated DC/DC-Converter.
The Noise source output (28V Noise Source) is also generated on this board.
All external supplies (Probe, Keyboard,...) are protected by polyswitches (current-dependent, self-
opening and closing fuses) or electronically against external short circuit.
On the motherboard a circuit for temperature-dependent instrument fan control is also implemented.
Probe / Keyboard
The probe / keyboard board is located at the front of the instrument frame and serves for supply and
connection of the connectors located at the front panel, the KEYBOARD (PS/2) and a PROBE POWER
connector. For connection with motherboard a ribbon cable is used.
Volume / Phones
This board is only fitted with option R&S FSP-B3 (AF-demodulator).
The volume/phones board is located at the front of the instrument frame and is used to connect the
rotary encoder for the Volume setting of the AF-Demodulator and the Headphones connector with the
motherboard.
For connection with the motherboard a 10-pin ribbon cable is used.
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