Matsushita Electric KX-TCD952NLB, Service Manual

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11.1.8. FACTORY SERIAL PORT (SEE Fig. 25)
In order to communicate with the handset during manufacture and servicing (using a PC) a
serial data link has been provided. Serial data input/output is provided on J6 (TP65), and a
ground is provided on J7. The bi-directional serial data line is split into two at IC1 pin 27 (input)
and pin 26 (output). Data rate is 9600 baud or 115.2 kBaud. D13 provides ESD protection, and
R37 and C56 provide RF de-coupling.
11.1.9. BUZZER CIRCUIT (SEE Fig. 29)
A square-wave signal from IC1 pin 45 is used to sound the buzzer via switching transistor T5
(TP22). Various tones and cadences are used dependent on function. Buzzer volume is varied
by changing the duty cycle of the drive waveform. D11 provides quenching of back-emf
generated when T5 turns off.
11.1.10. BATTERY SUPPLY (SEE Fig. 29)
The three cell NiCd/NiMH rechargeable battery supplies the handset via 2A fuse (actually a coil),
and is de-coupled by C3 and C4. It directly supplies T3 in the baseband section, and also the Tx
PA in the RF Section. It also supplies IC1 (de-coupled by C9), and most of the RF Section (VCC-
OC) (decupled by R35 and C47, C48 and VCC-PA).
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