JVC RX-D Series Training Book page 56

• Trigger with MASTER CLOCK signal, if the
MASTER CLOCK is missing, most likely -7v is
shorted by defective PWM ICs.
•Un-plug 4 connectors CN311/312/411/412 to
eliminate the bad effect on the PWM signal by power
amp stage.
•It is recommended to select the source on FM mode
and the DAP on ALL CH STEREO mode: Measure all
the 7 channels analog audio at CN521.
•The PWM is 50% duty when no audio input or the
master volume at 0. Increasing the audio level,
causes PWM duty cycle to vary.
•The FR (front right) channel is the only PWM signal
that cannot be measured in the front of PCB, it is at
one end of R317 that close to the IC201 of back side
of the PCB.