Measurements made yesterday indicated a problem on the SR2 (HSTS) M1 LF BOSEM channel (see LHO aLOG entry 12923), they also suggested it was an actuation issue and not sensing. This was confirmed this morning by applying offsets to each M1 channel in-turn and monitoring the sensor response (see SR2_M1_Offsets.png below).

Therefore, I've been further investigating this problem in the LVEA, first by using a break-out board at the Satellite Box (field cable H1:SUS_HAM4-10), to measure DC coil resistances as follows:-

T1 Pins = 10-23, R = 40.6 Ohm
T2 Pins = 7-20,  R = 40.1 Ohm
T3 Pins = 4-17,  R = 39.6 Ohm
LF Pins = 1-14,  R = Open Circuit

Thus verifying the issue was down-stream, i.e. either with the field cable or in-chamber.

I then repeated the same DC coil resistance measurements at the other end of the field cable i.e. the air side of the vacuum flange (HAM4-D6):-

T1 Pins = 10-23, R = 38.9 Ohm
T2 Pins = 7-20,  R = 38.4 Ohm
T3 Pins = 4-17,  R = 37.8 Ohm
LF Pins = 1-14,  R = 38.4 Ohm

Confirming that the issue resided with the in-air side of the flange with the field cable. I re-seated and tightened the connector at the flange and this rectified the problem.

Applying an offset to the M1 LF channel now exhibits the expected behavior (see SR2_M1_LF_Offset.png below).

A full set of TFs will now need to be taken to ensure there are no further issues with this suspension.

n.b. this issue is essentially identical to the loose cable connection at the air-side of the flange that was recently reported for H1 ITMX (see LHO aLOG entry 12544).