The signal path is described later in the service manual where you have gotten the schematic.

So when adjusting the bias voltage,in the beginning the trimmer should be full counter clockwise right? Thanks.

No! A good rule of thumb is to start with a trimmer in its center position, as that usually won't be far from its correct setting (if everything else in the circuit is fine). Besides, the amplifier PCB in Beomaster 3000 (-2) has left and right channels mirrored, so fully clockwise would mean max idle for one channel. Not good! Martin

Hello Dilen Thanks for the information. Btw the left channel in stage 3 amplifier the supply voltage is way down than the normal voltage.It is around 15 volt Although the rail voltage is 60 volt in tr57 for example all the voltages are around 16 Tr58 collector is 17 volt.Tr62 base is 15v Tr 61 collector 16v I have checked the resistors and there are all fine.I have isolated output  amplifier transistors nothing changes.I ve changed 558 553 capacitor still the same I moves the trimmer pot  few clicks behind and forward with no result Btw The trimmer works I get output signal in speaker but the voltages are not correct..