Kenwood KCH-19, Руководство по обслуживанию

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(No.RA019<Rev.001>)1-3
SECTION 1
PRECAUTION
This service manual does not describe PRECAUTION.
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
2.1 CIRCUIT DESCRIPTION
„ LCD Circuit
The LCD module is connected to the connector (CN4) of the Sub (Display) unit. The LCD module is controlled using parallel interface
(EMIF) from the MPU (IC706) of the transceiver main unit. The backlight of the LCD is controlled by the backlight driver (IC8). The
backlight driver (BD1754HFN) has a single-line digital control interface (UPIC) that can control the power ON/OFF and LED current
value through the EN pin. The backlight driver is controlled by I/O Expander (IC10).
„ Indicator LED Circuit and Key Backlight
Indicator LED and key backlight LED are controlled by I/O Expander (IC10). Indicator LED is consist of 3 color (Red, Green, Blue).
„ Key Detection Circuit
IC10 is I/O port expander with keypad matrix decoder. It handles key scanning and flag the MPU (IC706) of the transceiver main
unit via an interrupt line when key events have occurred. It communicates with the MPU via I2C serial communication.
„ Light Sensor Circuit
Light sensor (IC6) senses intensity of ambient light. The intensity value of ambient light is converted to digital signal and provided
to the MPU (IC706) of the transceiver main unit via I2C serial communication.
„ Power Supply Circuit
The battery voltage (SB) is provided from the transceiver main unit via SB and SP interface connector (CN2). The battery voltage
(SB) goes to 8 pin interface connector (J1). Other power supply (54M, 18M, 33M) is provided from the transceiver main unit via 50
pin interface connector (CN6). 54M outputs 5.36V and goes to illumination circuit, AVR_IC (IC1). IC1 (50M) outputs 5.0V. 18M out-
puts 1.8V and goes to LCD module. 33M outputs 3.3V and goes to AVR_IC (IC2). IC2 (30LCD) outputs 3.0V.
Fig.1 Power supply circuit
54M
illumination circuit
IC1
50M
Level Shift (3.3V >> 5.0V),
Analog SW
CN6
LCD Module I/O
18M
I/O Expander For 3.3V,
Light Sensor,
Level Shift (5.0V >> 3.3V)
33M
LCD Module VDD
IC2
30LCD
CN2
SB
8pin_interface_connector