Read Panasonic KX-NT700RU Service Manual online
10
KX-NT700RU
4.2.4.2.
DC loop circuit
In the off hook status, PC601 is ON.
DC loop path:
DC loop path:
RING - L604 - D613 - D612 - D604 - Q603(E-C) - Q602(C-E) - R656 - R655 - D604 - R616 - L604 - TIP
At this time, the output of the photo coupler PC605 changes level from High to low.
TIP - L604 - R616 - D604 - R655 - R656 - Q602(E-C) - Q603(C-E) - D604 - D612 - D613 - L604 - RING
At this time, the output of the photo coupler PC604 changes level from High to low.
At this time, the output of the photo coupler PC605 changes level from High to low.
TIP - L604 - R616 - D604 - R655 - R656 - Q602(E-C) - Q603(C-E) - D604 - D612 - D613 - L604 - RING
At this time, the output of the photo coupler PC604 changes level from High to low.
4.2.4.3.
Pulse dial transmission circuit
When the Off hook status, pulse dial transmission is executed by alternating On hook and Off hook.
The status of On hook or Off hook is controlled by the switching transistor Q603.
The status of On hook or Off hook is controlled by the switching transistor Q603.
Pulse dial path:
PB* IC1(13) - PB RA1 - PB CN3(20) - Flat cable - CN301(20) - RA302 - R654 - PC601 - R653 - Q603 (B)
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