Operating instructions

TECHNICAL DESCRIPTION
4-2
Power supply
C5903
AC-DC
CONVERTER
DC INPUT
11 - 32V
ON/OFF
AC INPUT
90 - 264V
45 - 440Hz
DC-DC
CONVERTER
DC OUTPUT
+24V
-24V
+12V
+5V
-12V
0V
COOLING FAN
CONTROL BOARD
Fig. 4-1 Block diagram of power supply module.
The power supply module is a switched mode design which will operate from an AC supply of
either 100 to 240 V~ at a frequency of 50 to 60 Hz, or within the range 108 to 118 V~, at a
frequency of 50 to 400 Hz; or from a DC supply of 11 to 32 V.
The circuits of the Service Monitor require the supplies tabled below:-
+5 V 3.0 A
+12 V 2.5 A
-12 V 1.2 A
36 V 100 mA output
The AC supply enters the instrument through a fused connector on the rear panel and then through
two poles of a 3 pole, push-button, ON/OFF switch situated on the front panel. From the switch,
the supply then passes to the power supply module. Here it is fed to a bridge rectifier in the
AC-DC converter to produce an unregulated DC supply. The voltage of this will depend on the
supply voltage, as the full AC input voltage range is covered without range switching.
The second stage of the AC-DC converter produces semi-regulated DC supplies of 12 V and 24 V,
using a 60 kHz switched mode oscillator and transformer coupling. This transformer also
provides the safety isolation barrier.
The DC-DC converter is driven by either the external DC supply or the DC supply from the
AC-DC converter.