Read Panasonic KX-NCP1174XJ (serv.man2) Service Manual online
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KX-NCP1174XJ
5.2.10. Bell Signal Generator
Bell signal for ringing an SLT is generated by amplifying the 20 or 25Hz square wave provided from MPR card to AC75Vrms
onboard. The SW power supply in the BELL circuit generates between +160V and -100V of voltage by switching the +40V from the
power source at 125KHz frequencies. The Bell signal picks up the square wave provided from MPR via a photocoupler, and it is
transformed into SIN wave, then amplified to AC75Vrm bell signal by the amplitude between +160V and -100V of voltage (Mainly
+30Vdc) produced by SW power supply.
When the Bell signal is not needed, bell signal voltage generating circuit can be turned off by transmitting H signal from P21 port
(BELL CNT) of ASIC to reduce the power consumption.
onboard. The SW power supply in the BELL circuit generates between +160V and -100V of voltage by switching the +40V from the
power source at 125KHz frequencies. The Bell signal picks up the square wave provided from MPR via a photocoupler, and it is
transformed into SIN wave, then amplified to AC75Vrm bell signal by the amplitude between +160V and -100V of voltage (Mainly
+30Vdc) produced by SW power supply.
When the Bell signal is not needed, bell signal voltage generating circuit can be turned off by transmitting H signal from P21 port
(BELL CNT) of ASIC to reduce the power consumption.
5.2.11. Bell Signal Transmission
AC 75Vrms bell signal generated onboard is transmitted to the individual port, then control the bell ON/OFF by making a bell relay
in each port (Bell signal ON) and by breaking it (Bell signal OFF).
The 16 ports do not ring simultaneously. They are divided into 4 layers to control ON/OFF. They are divided in to following 4 groups
(The ports in the same group ring simultaneously.): "1, 5, 9, 13", "2, 6, 10, 14", "3, 7, 11, 15" and "4, 8, 12, 16".
in each port (Bell signal ON) and by breaking it (Bell signal OFF).
The 16 ports do not ring simultaneously. They are divided into 4 layers to control ON/OFF. They are divided in to following 4 groups
(The ports in the same group ring simultaneously.): "1, 5, 9, 13", "2, 6, 10, 14", "3, 7, 11, 15" and "4, 8, 12, 16".
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