Panasonic KX-TDA0103XJ Service Manual page 52

KX-TDA0103XJ / KX-TDA0104XJ / KX-TDA0108XJ / KX-TDA0103X / KX-TDA0104X / KX-TDA0108X
2) 15V PT Output
2-1) 15V PT Output Converter Switching Circuit
The main converter output voltage is stepped down by switching choke coil L402, FET Q401 and diodes D412 and D414,
and then smoothed by electrolytic capacitors C417, C418 and C419. The smoothed voltage is regulated by the voltage of
Pin 9 of IC401 (on Sub board2).The ripple noise of the voltage is eliminated by the filter circuit L403 and C420.
Refer to Fig. 3-2 (B).
2-2) 15V PT Output Converter Controller Circuit
The signal from controller circuit centering on IC401 (on Sub board2) operates the switching part. The output from main
converter is stepped down and fed to the Vc terminal (Pin 20 of IC401). And then the oscillation signal from the OUT
terminal (Pin 2 of IC401) is led to the gate of FET Q401 through the transformer T402 to switch the voltage.
Refer to Fig. 3-2 (C).
2-3) 15V PT Output Over Current Protection Circuit
When Over Current flows to 15VPT output, a signal is sent from T401 to the over current protection circuit. Consequently
the voltage is input to CLM+ terminal (Pin 19) of IC401 (on Sub board2) and 15VPT output shuts down operating
intermittently.
Refer to Fig. 3-2 (A).
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