SERVICE MANUAL
LBB 3310/00, 3330/00 and 3331/00 page: 1 Date of issue:
4822 861 11006 July 1998
CONTENTS:
1. ABOUT THIS MANUAL............................................................................................................................3
1.1 Important safety instructions............................................................................................................................... 3
2. ABOUT THIS EQUIPMENT......................................................................................................................3
3. INSTALLATION .......................................................................................................................................3
4. ORDERING SERVICE INFORMATION....................................................................................................4
5. INTRODUCTION......................................................................................................................................4
6. CONTROLS AND INDICATORS..............................................................................................................5
7. TECHNICAL DATA ..................................................................................................................................6
7.1 CPSU.......................................................................................................................................................................6
7.2 Delegate and chairman units................................................................................................................................ 6
7.3 Power supply.......................................................................................................................................................... 7
7.4 Additional information ......................................................................................................................................... 8
8. MICROPHONE STEM ADJUSTMENT .....................................................................................................9
9. MAINTENANCE .....................................................................................................................................10
10. DIAGNOSTICS/ FAULT FINDING........................................................................................................11
10.1.1 Functional test.............................................................................................................................................. 11
10.1.2 Brief description of the various modes of the chairman and delegate unit................................................. 12
10.2 Measuring Instructions for the CPSU (LBB3310/00) .................................................................................... 13
10.2.1 Settings before you start measuring ............................................................................................................ 13
10.2.2 Internal Supply Voltages ............................................................................................................................. 13
10.2.3 Phantom supply of the external symmetrical microphone input................................................................. 13
10.2.4 Supply current measurement ....................................................................................................................... 14
10.2.5 AUDIO-CONTR to Loudspeaker circuit..................................................................................................... 14
10.2.6 External Microphone input to Line out (balanced) ..................................................................................... 16
10.2.7 Audio-Contribution and Audio-Distribution circuit.................................................................................... 18
10.2.8 LINE-IN to TELEPHONE-OUT, LINE-OUT, INSERTION-OUT Circuit................................................ 20
10.2.9 REC-IN-L and REC-IN-R to REC-OUT Circuit......................................................................................... 22
10.2.10 TELEPHONE-IN to LINE-OUT Circuit................................................................................................... 24
10.2.11 The mode switch........................................................................................................................................ 25
10.2.12 Functional test of the mode switch (S240)................................................................................................ 26
10.2.13 Functional test of system volume control (S260)...................................................................................... 27
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