This is unique to the CA-R1. You cannot set the DC offset like a normal amp. The Yamaha CA-R1 Service Manual BETTER explains the "Non-Signal Ground" method. Using a differential probe, you must adjust VR101 and VR201 to bring the floating ground within 0.5mV of chassis ground.

If the file refers to CA-R1 amplifier section (from a mini system like Yamaha GX-1 / GX-500 / GX-700), the service manual includes:

The “BETTER” version will make transistor pinouts readable — critical, because Yamaha often used proprietary part numbers (e.g., 2SAxxx vs “Yamaha 1234”).

With your high-quality PDF open, follow this accelerated service routine:

It appears there may be a typo in the model number provided. There is no widely known Yamaha amplifier with the model number "CA-R1".

It is highly likely you are looking for one of the following very popular Yamaha models with similar naming conventions:

If you meant the Yamaha CR-1 (Preamplifier), here is what the service manual typically contains:

The CA-R1 is known for its finicky Class A operation switch. The BETTER manual provides a step-by-step, mistake-proof guide to setting the bias current without blowing the output transistors—including oscilloscope photos of the correct waveform.