all 2.5V LO noted nets, are confirmed to be hardwired to the LO terminal
but the lead on U400 as selecable filter might be a good clue,
this meter do have fast / slow setting, all i need to do it is change settings, while monitoring the A0 A1 A2 signals on ADG633
EDIT : A0 is HI, when Filter is on, and A0 is LO when filter is Off
I did not plan to write the entire schematic, 2W and 4W ohm, is not of big interest right now (for me at least)
if any one else like to join and draw that part, feel free to say so :-)
ALSO there is a TL072 performing the current resistor amplification,
just under that, a bridge rectifier, funny construction, i assume it is so the DC current always go the same way ?
or is it only for overload protection ? i did not trace that part, it would require the pcb to be removed,
that was also not my plan.