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

 
 

 

 
Protection circuits are incorporated in the unit to prevent the failure of a single 
circuit or component from creating catastrophic damage. 
 
Transistor Q7541 monitors the UNR21V, UNR14V, +9(S)V, and +5(S)V line. If 
any of these supply lines develop a short circuit, transistor Q7541 goes into 
conduction and applies a high to pin 69 of the MPU, IC001, triggering an SOS 
condition. 
 
Transistor Q7544 monitors the +3.3V, and +2.5V line. If any of these supply lines 
increase in voltage transistor Q7544 goes into conduction causing its collector to 
go low. As a result, Q7541 conducts and applies a high to pin 69 of the MPU, 
IC001, triggering an SOS condition. 
 
The +9(M)V, and +2.5(M)V are also monitored for a drop in voltage. A decrease 
in any of these two supply lines forces the respective diode to conduct and 
trigger Q7542. A high is applied to pin 69 of the MPU, IC001, triggering an SOS 
condition.  
 
 
 

 

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