This comprehensive service manual provides detailed technical information for the Yamaha RX-V557, HTR-5850, and DSP-AX557 audio receivers. It includes in-depth schematics, component diagrams, troubleshooting guides, and repair procedures. The manual also covers the closely related models, the RX-V457, HTR-5840, and DSP-AX457. This resource is an essential tool for technicians and electronics enthusiasts seeking to understand and repair these Yamaha receivers. Whether you're facing a malfunctioning component, needing to replace parts, or simply desiring a deeper understanding of the receiver's internal workings, this service manual equips you with the necessary information to diagnose and resolve issues.