Signal Pass:
Refer to SIGNAL ROUTE ().
11. BLOCK DIAGRAM
12. CIRCUIT OPERATIONS
12.1. Telephone Line Interface
Circuit Operation: ( )...Line 2
This unit is connected to the telephone circuit by a 6-core full modular jack. When L1 (L2) key is
pressed, the speakerphone goes ON automatically, obtaining Line 1 (Line 2). An available line is
also selected and obtained by simply putting the handset into an OFF-HOOK status. Surge
absorbers SA1, SA2 are for surge suppression. The impedance of the unit is matched to each
Line by the circuit in the vicinity of Q5.
When Hook Switch is turned ON (OFF-HOOK), pin 72 of IC801 detects OFF-HOOK, pin 68 (pin 66)
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