Casio CTK-500 Service Manual page 8

Power IC (IC1: CA5668)
The power IC generates three voltages
analog circuit, and VCC (+9 V) for the power amplifier. VDD (+5 V) is always generated, but AVDD (+5 V)
and VCC (+ 9V) are controlled by the APO signal.
VIN
VDIN
+9V
GND
LED Driving
Chord Memory Play
Solo Sound
Duo Sound
Ensenble Sound
Beat (Jukebox)
Ad-Lib Musician
AVDD (+5 V) for the CPU and the reset IC, AVDD (+5 V) for the
CA5668
IC1
VDD
AVDD
VCC
APO
LED Driver
TC74CH174AP
IC3
D3
L0 Q3
L1
Q5 D5
L2
Q2 D2
L3 Q6 D6
Q1 D1
L4
L5 Q4 D4
CLK
CLR
VDD
— 6 —
APO VDD
0 V +5 V
+5 V +5 V
KO0
KO1
CPU
KO2
MSM6626-01
KO3
LSI1
KO4
KO5
KO17
AVDD VCC
0 V 0 V
+5 V +9 V