Read Panasonic KX-NT303X Service Manual online
5
KX-NT303X / KX-NT303X-B
4.2.
Circuit Operation
4.2.1.
LED Circuit and KEY Input Circuit
Circuit Operation:
A drive pulse wave, as in Fig.1, is output by IC1. That signal goes through the drive digital transistor and connects the key button
and LED cathode. By pressing the key, the drive pulse wave is input to Pin9~Pin11. In order to light the appropriate LED, the
LED control port is turned ON. That result LED is lit by the pulse Driver.
and LED cathode. By pressing the key, the drive pulse wave is input to Pin9~Pin11. In order to light the appropriate LED, the
LED control port is turned ON. That result LED is lit by the pulse Driver.
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