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and boots the CPU normally.
Voltage Regulator IC:
IC8 on CPU board is the voltage regulator IC with the low-consumption current of 3 volt and it
always supplies 3V to CPU.
Voltage Regulator IC:
IC9 on CPU board is the voltage regulator IC with the low-consumption current of 3 volt
equipped with control terminal. It is controlled by CPU to output C3V.
LED:
LED3 on CPU board is lighted up to indicate TX and RX: Busy. The green LED controlled by
CPU port is driven at Q19 while RX:Busy, and red LED is driven at Q13 while TX:Transmit.
LED:
LED1 and 2 is lighted up green for a fixed time as the back light during key operation. It is
controlled by pin 64 of the CPU port and driven at Q15.
Battery Voltage Detection:
Q18 on CPU board is used to check the battery voltage. While detecting the voltage, the gate of
Q18 becomes LOW by CPU port (pin 59), the voltage of the battery appears at the drain of Q18.
The voltage is divided by R62 and R63, and read by A/D input (pin 47), then the battery
indication appears on LCD.
External Microphone:
The external microphone connected to CN1 on CPU board causes the short between the
terminals 2 and 3 of CN1. In result the gate of Q17 and built-in microphone are connected to
earth. The signal from the built-in microphone is shut down and the signal from the external
microphone is supplied to pin 3 of IC11 via pin 1 of CN1.
21. TROUBLESHOOTING GUIDE
21.1. Transmission Trouble/ RF Circuit
Condition
Channel No. Setup
Standard Modulation (1KHz) Input
C3V Applied
MOD Signal: Pin9 (CN5) Check
TXP (3V): Pin11 (CN5)
TX (LOW): Pin12 (CN5)
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