Just to share with you, I just found this explanation:

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Beolab Penta 3

18th November 2012

This active loudspeaker gave normal results when playing but when the main system was switched off the indicator lamp at the base was sometimes observed to be glowing orange instead of the normal red. Since an orange light here indicates a fault (normally overheating or excessive DC at the output of the amplifier) the symptoms were investigated. Nothing could be found amiss except that even in “off” mode a small voltage drop was still present across the standby relay coil 4RL1. Since this same point also controls the driver transistor 2TR4 (BC557B) for the green section of the indicator lamp this was clearly the reason for the orange light. The relay control transistor 2TR3 (BC337-40) had a small and varying amount of bias present at its base but this was not coming from the preceding stage; instead 2TR3 was found to have had an internal c-b leak. A replacement transistor cured the fault. [

I located those two in the front control panel...

the guy wrote “2tr4” and “2tr3”... the values are the ones I got in the explanation but on the board I read “tr3” and “tr4” : did the guy made a mistake writing with a “2” , or should I find same transistor on another board ?

thanks !

The transistors TR3 and TR4 are on PCB 2, the Control board which, as you say, is the front panel.   So 2TR3 and 2TR4 refer to (PCB) 2 TR 3 and (PCB) TR 4.  The transistors you have identified on the board are the ones to change.   TR3 failing is a common fault  and can also be the cause of a Penta always being green and not going into standby (red).

The transistors TR3 and TR4 are on PCB 2, the Control board which, as you say, is the front panel.   So 2TR3 and 2TR4 refer to (PCB) 2 TR 3 and (PCB) 2 TR 4.  The transistors you have identified on the board are the ones to change.   TR3 failing is a common fault  and can also be the cause of a Penta always being green and not going into standby (red).

Thank you for this confirmation !!! 

Lets have the penta confirming that too 😁

and i confirm : working great !!!!!! 😁 😁 😁

TR3 changed.... (not received TR4 yet)

and i confirm : working great !!!!!! 😁 😁 😁

TR3 changed.... (not received TR4 yet)

and i confirm : working great !!!!!! 😁 😁 😁

TR3 changed.... (not received TR4 yet)

and i confirm : working great !!!!!! 😁 😁 😁

TR3 changed.... (not received TR4 yet)