Power Supply Circuit - Casio CTK-450 Service Manual

Power Supply Circuit

The power supply circuit generates three voltages - VDD (+6.0V) for the CPU and the reset IC, AVDD
(+6.0V) for the analog circuit, and VCC1 (+8.6V) for the pilot lamp and the power amplifier.
When turning power on, the 100 capacitor makes transistor T2 on first then the CPU provides transistor
T2 "High" of APO signal to keep it being on.
HOW TO GET POWER IN OPENING TOP PANEL
1. Remove the mode switch contact from the top panel.
A B
2. Make short-circuit and with a wire as shown below.
3. Connect an AC adaptor to the DC jack.
4. Place the contact on carbon paint of the mode switch.
5. Align the contact onto OFF position.
6. Slide the contact to PLAY position so that the pilot lamp lights up.
7. Take the contact off the carbon paint.
The unit will operate until disconnecting the AC adaptor or automatic power off, and it sounds at full
volume.
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B
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