Matsushita Electric KX-TCD952NLB, Руководство по обслуживанию

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8.3. THE LINE INTERFACE SECTION (SEE BLOCK DIAGRAM Fig. 19)
8.3.1. INTRODUCTION
This section consists of the telephone line interface, bell detector, hookswitch, pulse dialing
circuits, audio circuits, DC mask & line impedance circuits, power supplies, and battery charger
circuits.
8.3.2. TELEPHONE LINE INTERFACE (SEE Fig. 21)
The telephone line is connected (via 2 or 3 jumpers selected for country of destination) to a
bridge rectifier D8. Surge suppressor SA3 protects against excessive line voltages. Test points
are TP14 (A), TP13 (B), TP21 (S) and TP15 (E). Bridge rectifier D8 provides for lines of either
polarity. The output of D8 is “Line +” (TP50) and “Line -” which is ground.
8.3.3. EARTH RECALL (SEE Fig. 21)
For countries that require Earth Recall facilities, relay RLY1 is provided to short the E line to the
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