Panasonic KX-TDA0103XJ Service Manual page 38

KX-TDA0103XJ / KX-TDA0104XJ / KX-TDA0108XJ / KX-TDA0103X / KX-TDA0104X / KX-TDA0108X
3) 30V Output Voltage
3-1) 30V Output Converter Switching Circuit
The main converter output voltage is stepped down by switching choke coil L202, FET Q202 and diode D210, and then
smoothed by electrolytic capacitor C205. The smoothed voltage is regulated by the voltage of Pin 2 of IC201 (on the Sub
board 2).
Refer to Fig. 3-3 (B).
3-2) 30V Output Converter Controller Circuit
The signal from controller circuit centering on IC201 (on Sub board 2) operates the switching part. The output from main
converter is dropped and fed to the Vc terminal (Pin 7 of IC201). And then the oscillation signal from the OUT terminal (Pin
6 of IC201) is led to the gate of FET Q202 to switch the voltage.
Refer to Fig. 3-3 (C).
3-3) 30V Output Over Current Protection Circuit
When Over Current flows to 30V output, the potential difference between terminals of R202 and R203 occurs. The voltage
potential difference turns ON Q201 to send the over current signal to the control circuit. Consequently 30V output shuts
down operating intermittently.
Refer to Fig. 3-3 (A).
38