L

The power supply circuit has a voltage regulator and an APO (Auto Power Off) circuit. When power is ON and at the normal operation, the APO signal from the CPU keeps H level. Transistors T4 and T8 turn on, so that voltages VH, VL1, VL2 and VE are provided to the circuits. When the keyboard is not operated for seven minutes, the APO signal becomes L level. Transistors T4 T8 turn off causing the voltages to shut off. Voltages VA (5V) and VDD1 (ground) are always provided to the CPU even at the...

Schematic Diagram

Notes 1 AM capacitance values are indicated in uF lt p - 10pF . 2 All resistance values are indicated in ohms k 10 ohm, M lO'ohml 3 Large letter R represents a resistor's reference number e.g R19 Registor number 19 4 Refer to pages 14 15 for T waveforms and page 17 for their vestpomts, 15 Wire color code R - red, W - white. BL - blue

Troubleshooting

Does not work at all Pilot lamp does not light Check the voltages VA 5V , VE 3.35V , VC 5V and VD 5V . Check the reset and APO signals. Faulty parts Transistors T1 T4, Power switch, or CPU Does not work at all Pilot lamp lights Check the voltages VH 7.5V , VC 5V and VD 5V . Check the clock pulse and key common signals. Faulty parts Transistors T5 T8, Ceramic Trimmer Preset tone does not sound on PLAY mode Check the voltage VH 7.5V . Check the analog signal at base of transistor T11 or Power...

Electrical Specifications

Current Drain at DC 7.5V Input with 4 keys A4 thru D5 being pressed simultaneously and with tone at Flute, mode at Normal, envelope at G 5 2. Auto-power off Time when A4 is turned to 442 Hz with C4 key pressed in Flute 47kohm load at 10cm away from speaker with G5 key pressed in Flute tone 6. Minimum Operating DC Supply Voltage for sound to not distort noticeably 7. Mic Input Sensibility at 1 kHz for sampling 8. Line Input Sensibility at 1 kHz for sampling with A3 key by sampling external 1...