Field Service Manual: Philips CCS 400
This document is the Field Service Manual for the Philips CCS 400 conference system, Second Issue (Part Number: 4822 733 24251).
CONTENTS
- Tab 1: CCS 400 Introduction
- Tab 2: LBB 3300/00 Central Supply Unit
- Tab 3: LBB 3301/00 Interpreters + monitor distribution panel
- Tab 4: LBB 3302/00 Microphone plug in unit
- Tab 5: LBB 3203/00 Monitor Distribution Board (M.D.B.)
- Tab 6: LBB 3350/0x LBB 3351/0x Chairman / Delegate
- Tab 7: LBB 3352/04 Passive unit
- Tab 8: LBB 3360/20 Flush mounting delegate unit
- Tab 9: LBB 3361/20 Flush mounting chairman unit
- Tab 10: LBB 3386/11 LBB 3386/41 LBB 3386/71 Central control
- Tab 11: First line trouble shooting & service assemblies
- Tab 12: Second line trouble shooting
Chapter I: Introduction
Central Supply Unit/Interface (C.S.U.) LBB 3300/xx
The CSU controls the maximum number of simultaneously switched “on” microphones and provides volume control for the whole system, priority attention signals, and 3 dB attenuation of the audio signal when multiple microphones are active. It supplies voltage to delegate and chairman units, supports two chains of up to 35 units each, and connects up to 18 6-channel interpreter desks. Distribution to channel selectors is possible when a Monitor Distribution Board (MDB) is inserted. A telephone coupler, tape recorder, and line in/out connectors are available. A hand microphone can be connected via a plug-in unit (LBB 3302/00).
Brief Description of CSU and Peripherals
LBB 3300/xx Central Supply Unit (CSU)
A completely pre-wired unit with a basic PCB, a contribution panel, and a power transformer. Includes internal connectors for a roving microphone plug-in unit and an interpreter monitor panel + Monitor Distribution Board. Mains switch on the rear side. Connections for delegate's units, Tel. coupler, recorder, line-in/out, and hand-microphone are located on the front side.
LBB 3301/00 Interpreter + Monitor distribution Panel
Connects internally into the central supply unit via the contribution panel to the basic PCB. Interfaces 6-channel interpreter desks to the system and, if applicable, to the Monitor Distribution Board. Provides three extra external connectors for a monitor unit, a transmitter, and distribution.
LBB 3302/00 Handmicrophone plug-in unit + handmicrophone
Connects internally into the central supply unit. Interfaces the handmicrophone to the central supply unit, acting like a normal delegate's unit.
LBB 3203/00 Monitor Distribution Board (MDB)
Connects internally to the 3301/00. Provides channels 1-6 and floor for monitoring by program selectors. A selected channel is amplified along with the communication signal and routed via 3301/00 to the monitor connector.
LBB 3350/04 Table Top Delegate Unit
Features a built-in loudspeaker and microphone, microphone on/off button, pilot lamp, microphone “ON” indication lamp, microphone request lamp, jack for headphone connection, and automatic delayed mic. switching off circuit. The mic on/off button functions as a request button when a central control desk is in use.
LBB 3351/04 Table Top Chairman Unit
Features a built-in loudspeaker and microphone, microphone on/off button, pilot lamp, microphone “ON” indication lamp, priority microphone function, and jack for headphone connection.
Chapter 2: Brief Description of CSU and Peripherals (Detailed)
Discussion
Pressing the microphone button S1 on a delegate unit switches the microphone signal via a pre-amplifier to the audio line. The loudspeaker is automatically switched OFF, and microphone “ON” and pilot LEDs are switched “ON”. A switching control circuit (SCC) ensures that the maximum number of simultaneously active microphones is not exceeded. An audio level comparator automatically switches off the microphone if no speech is detected for approximately 30 seconds.
Conference
With a central control desk, S1 functions as a microphone request button. The SCC senses the central control unit, sending the request signal to the central control desk, illuminating the request LED on the delegate unit and the request lamp on the central control desk. The microphone can be switched ON/OFF remotely by the operator or by the delegate's own button.
Chairman
The chairman's unit functions like a delegate unit, with S1 for on/off. Priority button S2 allows the chairman to gain priority. Pressing S2 switches ON the chairman's microphone and its LEDs, and switches OFF the loudspeaker. It resets delegate units, switching their microphones OFF and loudspeakers ON, and sends a priority attention signal. Releasing S2 switches OFF the chairman's microphone and switches ON the loudspeaker. The chairman's microphone does not auto-switch OFF. Remote control for the microphone request function is available.
Basic Printed Circuit Board and Connector Panel (Key Functions)
The system incorporates mechanisms for priority signaling, audio signal mixing from various sources (line in, tape recorder, telephone coupler), and distribution to delegate units. An audio line stabilizer ensures a constant DC level on the audio line. An attenuator provides 3dB audio signal attenuation when multiple microphones are active. A limiter circuit restricts the number of active microphones. A dedicated interpretation system manages six channels, floor, and communication signals for interpreter desks and monitoring.
First Line Troubleshooting & Service Assemblies
CCS400 Audio Principle Overview
The Central Supply Unit (CSU) incorporates a mixing amplifier (IC4a) to combine various audio inputs (chime, telephone coupler, tape recorder, line in). It utilizes current modulators (TS14, TS4) to adjust microphone signals. The AC voltage on the audio line is adjustable in 3dB steps via switch S101. The AC voltage at the input of amplifiers A, B, and C in the CSU remains constant. In delegate/chairman units, the AC voltage on the audio line is amplified by IC1b when the microphone is switched off.
General System Test Guidelines
- Verify correct voltage selector position and mains fuse (2.5a slow).
- Check the 6-position system gain rotary switch for audio distribution.
- For automatic microphone switch-off, ensure the rotary switch for maximum microphones is in the “auto position”.
- Confirm interpreter desks are adjusted per the manual when using 6-channel interpreters.
- Adjust tape recorder input level potentiometer and impedance (S5) as needed.
- Verify telephone coupler jumper S4 for side tone reduction, and S2/S6 for input/output levels, ensuring CCS400 compatibility.
- Check jumper S3 for line input level and the system gain rotary switch for line output level.
Replacing Adjustment Resistor
If a microphone capsule is replaced in a delegate or chairman unit, the microphone amplifier gain (IC1a) must be re-adjusted. This involves placing a potentiometer or decade resistor between X2-5 and X2-6 in the IC1a feedback path and adjusting it to achieve a -7 dB level at mp7, which corresponds to an 85 dB SPL reference level.
Second Line Trouble Shooting: Soldering and Desoldering of SMD's
This section provides procedures for replacing surface-mounted devices (SMDs), including required tools (hot-air stations, vacuum stations, tweezers), materials (solder, paste, braided wire), and general hints for SMD handling. Emphasized practices include ESD protection, careful component placement, and precise temperature/time control during soldering/desoldering.