Logic Datum II internal wiring query

[Lucerne]

This Logic Datum II tonearm came with a recently acquired Mantra TT.

Its lost a cartridge tag but also looks to have the earth wire detached and I don't know why its hanging out the front and where it should need to be reattached / resoldered?

https://live.staticflickr.com/65535/55275145622_006375d8f8_b.jpg (https://www.flickr.com/gp/159688365@N08/d5w7828oTr)IMG_6079 (https://www.flickr.com/gp/159688365@N08/d5w7828oTr) by Neil Tully (https://www.flickr.com/photos/159688365@N08/), on Flickr

Its in very good nick so worth sorting. any ideas on where the (black) wire should be reattached?

[Barry]

The black wire is most probably intended to be attached to the outer metal screening enclosure of the cartridge. The fixed headshell looks to have a black anodised finish, which will be non-conducting, hence the need for the separate wire.

If you are going to use a Shure cartridge, be aware that the cartridge shielding is already connected to the ground pin of one of the channel outputs (I forget which one, but you can easily see it on inspection). In that case do not use the black wire as it would create an earth loop, possibly creating problems with "hum".

[Barry]

Has my reply been of help Neil?

[Lucerne]

Hi Barry, apologies for slow reply, for some reason I couldn't get logged onto AoS for a couple of days?

Yes thats very useful. I've not seen that on any arm before but your suggestion sounds correct.

I'm going to get a meter on it when I can get a chance to confirm continuity and whats connected to what. I'll report back on conclusion.