Casio CTK-500 Service Manual

— 5 —
From the CPU
To main volume
FIlter Block
Since the sound signall from the CPU is a stepped waveform, the filter block is added to smooth the
waveform.
VDD
1K
AG
AG
AG
10K
10K 6.2K
C562(H)
C222(H)
C331J
2SC3112B
VDD
CPU
MSM6626-01
LSI1
VDD
ON
OFF
ON
OFF
MI
KO11
KI1
KI0
Power Switch
ON
KO18
APO signal
OFF: 0V
ON: +5 V
Power On/Off Circuit
When the power switch is turned on, a low level differential pulse is provided to terminal MI of the CPU.
Upon receipt of the pulse, the CPU starts the power ON sequence and raises the APO signal to +5 V.
When the switch is off, on receiving the KO11 signal at terminal KI0, the CPU drops the APO signal to
ground level to shut down power.
Initial Reset Circuit
When batteries are set or an AC adapter is connected, the reset IC provides a low pulse to the CPU.
The CPU then initializes its internal circuit.
VDD
Battery set
RESET
CPU
MSM6626-01
LSI1
Reset IC
S8053ANO
IC4

Casio CTK-500 Specifications

General

Brand	Casio
Model	CTK-500
Category	Electronic Keyboard
Language	English