We were lucky yesterday when we connected the REFL DC to the Tabletop Interface Box on the EY ISC table.  The signal arrived in digital land in H2:ISC-ALS_EY_PDH_DC as expected.  None of the other 3 DC signals work (IR_PWR, GR_PWR and BB_PWR).  I connected BB DC to the TTIF box Ch4, and found that it arrives at the concentrator in the field rack (D1102045 #36, on cable 73), but I didn't continue tracking the problem beyond that.