NAS-S55HDE, NAS-SC55PKE, SS-S55HDE - Sony Audio Service Manual (repair manual). Page 7

DISCHARGE  PROCESSING
1.  Switching power block on primary side of main board
 

Though high voltage of 280V is applied to the electrolytic capacitor (C205), in about 3 seconds after the AC cord was unplugged, the 
voltage will lower to 3 to 4V.

 

However, in the case of standalone main board, the discharge time will be long because of small load.

 

The voltage at this time is about 290V.

 

The voltage becomes half in about 20 seconds after the AC cord was unplugged. After that, in about 5 seconds, the voltage will lower 
to about 3V rapidly.

 

Then, the discharge slows and accordingly the forced discharge processing is necessary.
•  Forced discharge processing method
  Connect a resistor such as 100Ω 3W to the terminals of C205 and execute the discharge processing. (Discharge for about 10 sec-

onds)

Note: The potential of about 145V exists across aluminum case of C205. You could get an electric shock if you touch the aluminum case of C205.

2.  Power block on secondary side of main board
 

In about 3 seconds after the AC cord was unplugged, almost all potentials will lower to below 3V, but after that the discharge slows and 
accordingly the forced discharge processing is necessary.
•  Forced discharge processing method
  Connect a resistor such as 100Ω 3W to the terminals of C308 and C310, and execute the discharge processing. (Discharge for about 

5 seconds)

 

For electrolytic capacitors other than C205, 308 and 310, the discharge processing is executed simultaneously with the above discharge 
processing, and therefore the forced discharge processing is not necessary.

Ω/3W

Ω/3W

Ω/3W