1 300L Controls and Connectors Mounting ....................................................................................... 1-2 Power Requirements .................................................................... 1-2 Rear Panel .................................................................................... 1-3 Connectors and Cables ................................................................ 1-4 About the LARC ............................................................................ 1-6 How to Interface the LARC ........................................................... 1-7 Setting Analog Audio Levels ......................................................... 1-8 Periodic Maintenance ................................................................. 1-10 Ordering parts ............................................................................. 1-10 Returning units for service .......................................................... 1-10 Table of Contents 2. Performance Verification Introduction ................................................................................... 2-2 Initialization and Inspection .......................................................... 2-3 Power Supply 2-4 Power Fail ..................................................................................... 2-5 Timecode Tests ............................................................................ 2-5 Listening ....................................................................................... 2-6 Audio Proof of Performance ......................................................... 2-7 Level Test • Frequency Response • Noise • THD Crosstalk • Power Up • Shock DSP Board Troubleshooting ....................................................... 2-10 Cable Connections ..................................................................... 2-10 Audio Problems .......................................................................... 2-11 One Channel Bad • Both Channels Bad • No Output No Output with no relay click on power up • Effects don't sound the same as when stored • The LARC control head will not light • Touching a LARC slider resets unit Audio Precision ATE Test Descriptions ...................................... 2-13 3. Circuit Description Architectural Overview .................................................................. 3-2 Host Board .................................................................................... 3-3 68008 Bus Interface ..................................................................... 3-5 Interrupts ...................................................................................... 3-6 Memory ......................................................................................... 3-6 The DUART .................................................................................. 3-7 Duart Interrupts • DUART Input/Output Ports • DUART Input Ports • DUART Output Ports Time Code Chip Select ................................................................. 3-9 Limits of Operation ....................................................................... 3-9 System Clock Generation Circuits .............................................. 3-11 Master Clock • Clock Source • Sample Clocks Phase-Locked Loop .................................................................... 3-12 The Phase Comparator • Loop Filter • The VCO Input/Output Audio Level Strobe ................................................ 3-13 Z80 DMA Access ........................................................................ 3-14 Digital Interface Board ................................................................ 3-17 AES/EBU Interface • EIAJ CP-340 Interface • Time Code Input • EMI Considerations DSP Board .................................................................................. 3-18 DSP Slaves - Lexichips .............................................................. 3-19 Z80 Control Processors .............................................................. 3-19 Z80 DMA Interface • Slave Control Status Registers Slave Status Registers ............................................................... 3-21 Wait State Generation ................................................................ 3-22 Audio Routing Data .................................................................... 3-22 Routing Implementation • Input Routing • Output Routing Lexichip I/O ................................................................................. 3-24 Lexichip Input • Lexichip Output • Inter-Lexichip Communication Digital Filter ................................................................................. 3-25 Peak-Detect ................................................................................ 3-26 MIDI ............................................................................................ 3-26 Audio RAM Boards ..................................................................... 3-26 Analog Boards ............................................................................ 3-27 Analog I/O Board • Analog Motherboard • Differential Input Circuitry • Programmable Input Gain Circuitry • Pre-Emphasis/ Input • Offset Servo • A/D Conversion • D/A Conversion Output Filtering • Programmable Output Gain Circuitry Balanced Output Driver • Voltage Regulators and Relay Drivers Power Supply Board ................................................................... 3-30 LARC .......................................................................................... 3-31 Power Supply • CPU • Reset Logic • Address Decoding Logic • ADC Logic • UART Logic • RS-422 Logic • Litronix Display Logic • Buffered Bus and Sink Logic Specifications Parts List