Knowledge about the BL3500
Link to BW product page: https://beoworld.co.uk/prod_details.asp?pid=373
Link to BW faq regarding BL3500: https://www.beoworld.co.uk/faq_view.asp?id=80
Beolab MKI (originally called LCS 9000) has an 8 pin connector on the back marked MCL. serial numbers are lower than 19343452
Beolab MKII has an 8 pin connector often refered to as powerlink on the back, but according to the servicemanaul for BL3500 MKII only intended for use with Beolink Wireless 1 (W1). No pinout for the connector is shown in the service manual other than pin 6 in the Din connector being data. Serial numbers on BL3500 MKII are from 19343452 and up
Not confirmed knowledge about the BL3500
A user on Reddit https://www.reddit.com/r/BangandOlufsen/comments/rvr4f4/best_way_to_modernise_a_beolab_3500_soundbar_as/ apparently has a setup with a BL3500 MKI (SW 1.1) where he is injecting 5V from a USB power adapter to turn It on. User Matator has been in contact with this person who has mentioned that the power is connected to pin 1 and 7 on the DIN connector. It has not been possible for Matador, Guy or me to replicate this in our test’s in this thread https://beoworld.org/forums/topic/beolab-3500-and-1611-converter-settings/page/17/#post-16910 Nor with the reverse pin combination (pin 3 and 6) or the dataline and its shield (pin 6 and 7).