Panasonic KX-TDA0103XJ Service Manual page 59

8.3.1.6. Protection Circuit
This section explains about the Over Voltage Protection Circuit, Over Heat Protection Circuit and Battery Reverse Connection
Protection Circuit.
1) Abnormal Condition Detection Circuit
Abnormal condition detection circuit consists of thyristors Q524 and Q525 (on Sub board2).When power supply operation
becomes abnormal, the abnormal detection signal is sent and Q524 and Q525 are turned ON. A current flows through the diode
of PC4, which is sent to the latch circuit of main converter, and the operation of main converter is stopped. (Refer to Main
Converter (P.48))
Refer to Fig. 6 (C).
2) Over Heat Detection Circuit
When internal temperature of power supply rises abnormally, resistance values of posistors PTC501 and PTC502 become
High, transistor Q511 (on Sub board2) turns ON, and the voltage from dropper circuit is sent to the abnormal detection circuit
through zener diode D529 (on Sub board2).
Refer to Fig. 6 (A).
3) Battery Reverse Connection Protection Circuit
When the battery is connected to the unit in the wrong direction by mistake, the voltage of plus terminal becomes minus. Then
diodes D523, D524 and D525 turn ON. The transistor Q511 (on Sub board2) turns ON, and the voltage from dropper circuit is
sent to the abnormal detection circuit through zener diode D529 (on Sub board2).
Refer to Fig. 6 (A).
KX-TDA0103XJ / KX-TDA0104XJ / KX-TDA0108XJ / KX-TDA0103X / KX-TDA0104X / KX-TDA0108X
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