This is an original service manual for the Pioneer SX-4 receiver, a vintage audio component that belongs to the Pioneer brand. It contains detailed information about the inner workings and technical specifications of this device, which can be very useful for enthusiasts, collectors, and repair technicians. The manual is in good condition and has been well-preserved over time, ensuring that its contents are still legible and relevant. Whether you want to learn more about the SX-4 or need to troubleshoot an issue, this manual can be a valuable resource for you.