2. BACK SURROUND B'D 
 : 5 Min. After power on, please set up Bias as below, 
   SBL > adjusting VR31 check P301 to 23mV +2mv/-1mV.
   Center > adjusting VR41 check P308 to 23mV +2mV/-1mV.
   SBR > adjusting VR51 check P309 to 23mV +2mV/-1mV.
 P301 VR31 BACK SURROUND L-CH      VR41    P308 CENTER-CH
AVR325                       harman/kardon