Casio CTK-620L Service Manual

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POWER SUPPLY CIRCUIT
The power supply circuit generates seven voltages as shown in the following table. VDD voltage is always
generated. The others are controlled by APO signal from the CPU.
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, and clears the working storage RAM.
When the power switch is pressed, the CPU receives a low pulse of POWER signal. The CPU sends APO
signal to the power supply circuit, also sends a reset signal to the DSP.
Reset IC
IC1
RN5VD40AA
DSP
LSI2
HG51B277FB-1
VDD
Reset signal
To power supply circuit
VDD
Battery set
RESET
VDD
POWER
From power switch
NMI
RSTB
RESB
APO
PLE
CPU
LSI1
GT913F
SCK0

Casio CTK-620L Specifications

General

Brand	Casio
Model	CTK-620L
Category	Electronic Keyboard
Language	English