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Beolover SyncDrive: DC Platter Motor Replacement for Beogram 4002 and 4004 (Type 551x and 552x)

Late Beogram 4002 and the 4004 (Types 551x and 552x), which have DC platter motors instead of the earlier synchronous AC motors usually suff...

Sunday, January 29, 2017

Beogram 4000: Replacement of Corroded DIN5 Plug and Installation of a Grounding Switch

After rebuilding the control cluster the next step of my current Beogram 4000 restoration was to replace the original corroded DIN 5 plug with a modern gold plated all-metal plug, and to install a switch that allows connecting system and signal grounds in case there is a ground loop causing a hum in connection with the amplifier. This shows the rusty original plug:
And here the replacement:
Pretty! On to the grounding switch. This shows the terminals where the DIN cable is connected to the internal cartridge wiring:
This is the perfect spot to install the switch:
This switch allows to toggle between the B&O-original setup, where signal and system grounds are kept separate, and a configuration where both grounds are connected. B&O actually adopted this configuration in later 4002 and the 4004 Beograms. My experience is that if there is a hum, this connection in most cases suppresses it.




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