Matsushita Electric KX-TCD952NLB, Service Manual

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is complex to achieved the correct frequency response, since the line load (for UK) is also
complex. The line input signal TXAF (TP123) is taken from the junction of R41 and R70. Phase
cancellation of the line output audio occurs at this point, so that only incoming line audio
should be passed to the BBIC on TXAF.
Circuit Diagram
8.3.9. POWER SUPPLIES (SEE Fig. 23)
The AC Adaptor for the KX-TCD952NLB consists of two separate isolated DC supplies providing
a +8 V supply for the base circuitry, and a 9 V supply only for the charger circuit. The isolation is
because the main base circuitry is connected to the telephone line, so potentially hazardous
voltages may be present, while the charger circuitry has charge contacts that could be touched
by the operator, so the two supplies must be kept separate. The 8 V supply from the AC Adaptor
is connected via J2 pin 1 (TP90) +8 V, and J2 pin 2 (TP89) ground. The unreg8 V supply
is fed to the first regulator.This regulator IC7 provides a regulated output pin 2 (TP91) of +4.0 V
(4V). The second regulator IC6 is fed with +4V and provides the 3.0V supply
(TP95). During power-up this regulator generates a RESET signal (TP94) which is used to reset
the microcontroller and BBIC.
8.3.10. BATTERY CHARGER (SEE Fig. 23)
The 9 V supply from the AC Adaptor is connected via J2 pin 6 (TP82) positive, and J2 pin 5
(TP78) negative. Theconstant current battery charger circuit is made up of T14 and T15 (series
pass transistor) and associatedcomponents. Charging detector circuit T16 switches on when a
charging current flows through R64 and D11, and turns on the “Charging” LED D12. The charge
contacts are J3 (TP89) positive and J4 (TP88) negative.Charge current flows in via J4, through
T15, R63, AC Adaptor 9 V supply, R64, D11, and out via J3.
Circuit Diagram
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