JVC RX-D Series Training Book page 54

•Trigger with the MASTER CLOCK signal,
which is at pin 4 of FW323.
•It is recommended to either turn the volume
level to 0 or to not use an audio signal input.
the PWM waveform should normally be at
50% duty cycle.
•Select the FM mode and tune to a station
with good reception. We can measure the
analog audio signal at CN521, even with
CN111 unplugged (no +/-B power).