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POWER SUPPLY CIRCUIT
The power supply circuit provides various voltages as shown below.
The voltage VDD (+5 V) is provided as long as batteries or AC adaptor is set.
Other voltages are controlled by APO (Auto Power Off) signal from CPU.
The regulator IC BA9700A generates square waveform from pin 5 as PWM (Pulse Wide Modulation).
The LC filter makes stable output voltage (+5 V) for each circuit as shown above.
LC Filter
(To digital)
(To analog)
(To FDD)
(To LCD)
CPU
HD6433048SA89F
LSI9
PA7
NMI
PW/SW
APO
NMI
PW/ON
APO
Summary of Contents for WK-1800
Page 30: ...29 PRINTED CIRCUIT BOARD Main PCB JCM733 MA1M Top View Bottom View 1 6 5 4 3 2 9 10...
Page 31: ...30 Sub PCB JCM733 MA2M 7 8 Sub PCB JCM733 MA3M Top View Top View...
Page 32: ...31 Console PCBs JCM733 CN1M Top View Top View Console PCBs JCM733 CN2M...
Page 33: ...32 Display PCB JCM733 LCD1M Top View Bottom View...
Page 34: ...33 Keyboard PCBs JCM763T KY1M Top View Top View Keyboard PCBs JCM763T KY2M...
Page 40: ...39 SubPCB JCM733 MA2M MA3M 7 8 Regulator IC Power Amp...
Page 41: ...40 Console PCBs JCM733 CN1M CN2M S Register S Register...
Page 42: ...41 LCD Driver PCB JCM733 LCD1M LCD Driver Back Light Circuit...
