Table of Contents
Advertisement
5. SM40 SURVEILLANCE CENTRE MODULES
5.6.1 Reduction of power dissipation in amplifiers.
To reduce the power dissipation in amplifiers when surveillance is used, the Amplifier Surveillance Board
(LBB 1368/00), the Loudspeaker Surveillance Board (LBB 1367/00) and the Pilot Generator Card (LBB
1369/00) have been modified. The modification enables a 20kHz 'burst-pilot-tone' to be used instead of a
continuous 20 kHz 'pilot-tone'. This feature can be selected by a jumper located on the Pilot-tone
Generator Card. The modified type number versions are compatible with previous versions and can be used
all together in a single system.
Modification to Amplifier Surveillance Board LBB 1368/00
The 20 kHz detection circuit, built around TS32 is additional for the burst-mode. The relay K1 has been
changed into a 'make-and-break' contact relay. The modifications are implemented in the factory from serial
number 7238 onwards.
Modification to Loudspeaker Surveillance Board LBB 1367/00
The 20 kHz detection circuit, built around IC1 has been modified for the 'burst-mode'. The modification
has been implemented in the factory from serial number 19366 onwards.
5
41
Advertisement
Table of Contents
