Read Panasonic KX-TCD951EB / KX-TCD955EC Service Manual online
27
KX-TCD951EB/KX-TCD955EC
3.9 POWER SUPPLIES (SEE Fig. 23)
The AC Adaptor for the KX-TCD951EB / KX-TCD955EC 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 unregulated +8 V supply is fed to the first regulator.
This regulator IC7 provides a regulated output pin 2 (TP91) of +4.0 V (called +4V)
.
The second regulator IC6 is fed with +4V and provides the stable +3.0V supply (TP95). During power-up this
regulator generates a RESET signal (TP94) which is used to reset the microcontroller and BBIC.
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. The
constant current battery charger circuit is made up of T14 and T15 (series pass transistor) and associated
components. 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
VUNREG
RESET
Fig. 23
Click on the first or last page to see other KX-TCD951EB / KX-TCD955EC service manuals if exist.