Power Down Detection Circuit - Casio QT-2000 Service Manual

5-5. Power down detection circuit

IC48 : Detection IC
The power is supplied at CN16 from switching power supply unit.
When the VP voltage become more than 22V, the voltage appears at pin No.2 of IC48 through
the zener diode ZD2.
The detection IC outputs "High" signal from pin No.6 and its signal going to IC45.
Then, the signal "INTPWD" becomes "High" and going to GA2.
The GA2 outputs "Reset" signal and reset the all GAs.
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