Introduction; Short-Circuit Protection; Circuit Diagram - SoundCraft CPS250 User And Technical Manual

Introduction

WARNING: THIS APPARATUS MUST BE EARTHED
The CPS250/CPS275 are linear power supplies which, like other linear supplies,
produce DC voltages by rectifying, smoothing and regulating AC voltages from the
secondary windings of a mains transformer. Soundcraft mixing consoles employ a
number of dc voltage supply levels in their operation and these are all provided at the
output of each supply unit.
The CPS275 provides higher currents than the CPS250. The CPS275 also has the
capability of being linked to a second CPS275 to provide automatic power backup in
the event of one of the units failing.
In regulating these voltages there is considerable heat generated, the dissipation of
which is achieved through a substantial internal heat sink. A fan is incorporated which
draws air over the heatsinks to provide adequate heat dissipation for the regulators
and reduce the outer case temperature.
The CPS250/CPS275 is designed for installation in a 19" rack unit, occupying 2U of
rack height. Refer to the section "RECOMMENDATIONS FOR INSTALLATION"
on Page 5.
LED indication is provided on the front panel to show operation of the regulating
circuits.

SHORT-CIRCUIT PROTECTION

The +/-17V rails can withstand a short to ground or each other for up to one second;
if the short circuit remains for longer than one second then both of the 17V rails will
be shut down. To reset them the supply must be switched off for 6 seconds and then
switched on again.
The +5V and +48V are current limited and will self recover when any short circuit is
removed.
2 Introduction