KX-NT366RU (serv.man2) — Panasonic PBX Service Manual (repair manual). Page 6

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6
KX-NT366RU/KX-NT366RU-B
4.2.
Circuit Operations
4.2.1.
Main-CPU (IC1)
The DSP , MAC, CODEC and the CPU are built into the VoIP (IC1).  
The FLASH (IC2) and the SDRAM (IC3) are connected to the CPU. The contents of the FLASH are expanded to the SDRAM at
start-up. It also stores each setting.  
If the LCD is not displayed in the operation but there is no problem on the LCD, then the failure of the CPU system memory (IC2
and IC3) should be considered.
4.2.2.
LCD Circuit
LCD data are outputted from pin 54 of IC4 to LCD module.
IC19 is an inverter for a charge pump circuit which outputs the voltage necessary for LCD driving.
• 4.5V from -1.2V generated at IC19 as a reference to +3.3V of the power supply voltage is pressurized four times in the LCD mod-
ule and used as LCD driving voltage (approx. 18V).
LCD contrast is set by electronic volume in the LCD module.
The type of the LCD module is distinguished by pin 56 of IC4.
KX-NT366 uses a 24 digits x 6 lines LCD.
The lighting of the backlight is controlled by Q601.
• IC4-pin 52 H
→Q601-ON→Backlight ON
• IC4-pin 52 L
→Q601-OFF→Backlight OFF
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