Casio CE-2400 Service Manual

Also see for CE-2400: Operator's instruction manual Operator's instruction manual Operator's instruction manual

Contents

Casio CE-2400 Service Manual Manual pdf 11 page image

— 9 —6. CIRCUIT EXPLANATION6-1. Power supply circuitQ1 : Transistor for controlling voltage (VP)Q2 : Transistor for voltage detectionQ3 : Transistor for controlling power down (PWD) signalZD2 : Zenner diode for controlling base current of Q2ZD3 : Zenner diode for detecting power down (PWD) signalAfter plugging the AC cord into the outlet, the AC voltage (23.8 V) appears at CN1 connector.Then this voltage is rectified by the diode bridge and it become constant voltage through the capacitorC1.[Voltage VP]A constant voltage (31.4 V) appears on the "2" position. This voltage made from the constantvoltage circuit consist of transistor Q1 and Q2, zener diode ZD2, resistor R7, R8, R12 and R13.[Voltage VLED and VCC]The voltage goes to pin No.1 of regulator IC1 and then it is out from pin No.2 of IC1 as stablevoltage (5.6 V).Then this voltage falls down to 5 volts through the diode.It is used for VCC (for logic) and VLED (for display drive).Also, it goes to pin No.4 of IC1 and using to control the output voltage level.Inductor L1 is used to stabilize the VCC voltage when the drawer opened.FROM TRANSFORMERF1 D2 1SR35-100A1SR35-100A1SR35-100A1SR35-100AD1D4D3C450F2S683JCN15277-02A12C1 3300μF50WVQ2R121K2SC4640C5C103ZD2RD7·5EB3R132.7KR8R7C95.1K820ZD3R15 10KRD16EB3Q32SC46401μF50WVC650RE2-47R14100KD91S2473Q12SD1196WITH HEATSINKOSH-1625-SPIC1VIN 1 VINGNDVOUTLM2575T-5.03425 ON/OFFOUTPUTFEEDBACK47~63KHzMCDR1419-681KL1D8RK-1425RE2-330C81S2473D7D111S2473PWDVP 24VVLED 5.6VVCC 5.0VGNDPGNDGND12 5 7 8 9346101112