Yamaha RX21 Owner's Manual page 5

Y =)
PA-1 POWER SUPPLY
CV ~ OUTPUT TO SOUND/MONITOR SYSTEM
РУМ POWER ON/OFF
OTHER
SOURCES MULTITRACK RECORDER
CTO SEL PA OR
RECORDING MIXER
CASSETTE "IN" OR "MIC" JACK CASSETTE"OUT" OR"EAR" JACK
ay
DATA CASSETTE RECORDER