Panasonic gp6d th-42px20u th-50px20u th-42pa20u th-37pa20u update information Service Manual

 

 
The standby power supply provides the necessary DC voltage for the system 
control Microprocessor, Reset circuit and the EEPROM. D404 rectifies the 
incoming AC Voltage and applies it to the transformer T402 and the standby B+ 
control circuit IC401. The output pulses of IC401 are then applied to the primary 
side of transformer T402. Diode D409 rectifies the AC output at pin 12 of the 
secondary of T402 to create the STB 7V for the system control circuit. IC403 
regulates the 7V standby voltage to produce the STB5V for the D Board. This 7V 
standby voltage also passes through the diode D410 to enter the power relays 
RL401 and RL403. When the unit is turned on, transistor Q401 turns on to create 
the ground path for power relay RL401. Transistor Q417 provides the ground 
path for the In Rush Current relay RL403. IC 402 and the Opto-coupler D408 
provide feedback to the STB control circuit for voltage regulation. After the main 
power supply goes into operation, the 5V source is applied to transistor Q402 to 
turn on the relay RL402. 
 
 

 

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