Read Panasonic KX-UT248RU / KX-UT248RU-B (serv.man3) Service Manual online
7
KX-UT248RU/KX-UT248RU-B
4.2.
Circuit Operations
4.2.1.
LCD / BACKLIGHT Circuit
LCD module is connected to main PCB with CN501.
LCD data are output from IC503 to LCD module.
LCD contrast is set by electronic volume in LCD module.
LCD data are output from IC503 to LCD module.
LCD contrast is set by electronic volume in LCD module.
LCD DRIVER voltage (LCD internal voltage : 20V) is supplied by external voltage (24V) observed between Pin 17 and Pin 18 of
CN501, and LCD LOGIC voltage (3.3V) is observed between Pin 11 and Pin 10 of CN501.
CN501, and LCD LOGIC voltage (3.3V) is observed between Pin 11 and Pin 10 of CN501.
The lighting of the backlight is controlled by Q501.
The PWM (Pulse Width Modulation) signal is output from pin F17 of IC503 pin and the brightness is changed according to its duty
ratio.
The PWM (Pulse Width Modulation) signal is output from pin F17 of IC503 pin and the brightness is changed according to its duty
ratio.
4.2.2.
Reset Circuit
Reset Signal is output from IC505 and input into IC503-Pin A14.
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