Fellow B&O enthusiasts,   Summary: okay, so recently the Beosystem 3 stopped channeling sound to my center loudspeaker: Beolab 7.4. So I got another one delivered and the issue continues to persist on both BL 7.4s. I use a Beo4 remote to send signals to the surround system and switch between various stereo, 2.1, 5.1, 7.1 modes.   Details: Interestingly, the green light on the back is ON on both 7.4s, so that indicates that two 7.4s are able receive power. I swapped various 8-pin din mk3 cables as well, and ruled that out too. So its not the power line or the audio cables. After dialing up some b&o colleagues / dealers / experts, it may be something to do with the "digital sound module" in the Beosystem 3. After this sound glitch surfaced, I performed a teardown of BS3 unit and reconstructed it and everything works just fine in the 5.1/7.1 setup as before the teardown, such as the BL6000, BL4000, and BL1s -- Except you got it the 7.4s! One) Where may I purchase a digital sound module fully tested and functioning normally?A reliable guy quoted me around 250. And I'd like to obtain a few more quotations or find an economical workaround ideally :-). Of course, if you think the issue may be something else in the menu settings or something kindly advise. I'm always tinkering with the system settings and it may very well be something I toggled ON or OFF inadvertently, pffff. In summary, something in the beosystem 3 appears to be blocking the sound to the BL 7.4 mono speakers. For some unknown reason. It's proving to be beyond my know-how.   Two) Notably, I'm also looking to figure out what type of BSys 3 it is as part of my digilience: Mark I or Mark II or Mark III. Ideas on where to look?   Any other perspective, questions, comments and/or trouble shooting tips? Look forward to seeing where this leads and gaining the benefit of our global community's collective wisdom! ...

Johan thanks for the resource in narrowing down the mark type! Awesome sleuthing. So interestingly, the 7.4 are now channeling audio and sound crystal clear. It was something to do with the voltage setting on my transformer given the 7.4 center speaker is 230V rated I did not have enough  voltage going to the speakers given Im in the Us on a 110 voltage household circuit — though the green light was on. Anyway a simple adjustment on the plug-in-the-wall transformer from 110V output to 220V output did the trick. A few people who I met on a trip to the local bang and olufsen store encouraged me to keep tinkering and ….voila!   anyway just a positive update for those who may run into similar issues now or in the future :-)

Hello Elephantsintheclouds, My BV 9 has the same sympton, can you explain me how did you solve the no sound in the central channel? It was only the 110/220v you mentioned? I'm in Europe and the 22oV is present Is there any known problem with the powerlink exits on beosystem 3? Thanks a lot