This comprehensive service manual provides detailed technical information for the Yamaha RX-V3900/DSP-AX3900 AV receiver and amplifier. It is designed for service personnel and covers a wide range of topics, including front panel and rear panel descriptions, remote control panel details, thorough specifications, internal component layouts, and detailed disassembly procedures. This manual also includes instructions for updating firmware and utilizing the self-diagnostic capabilities of the receiver. The wealth of information presented ensures technicians have access to all necessary tools for effective troubleshooting, repair, and maintenance of these sophisticated audio-visual components.