ITMX seemed to be extra sensitive to larger ground motions--it was often the only ISI to trip.  Of course somebody had to be the most sensitive so could be a wild chase.  FRS 5948.

LHO aLog 28567 -- Investigation first report finds wierd reversal of current in Stage2 H2 CD.  Some more data from EQ (only ITMX tripped) 28621.

LHO aLog 28649 -- Direct excitation of CD leads to finding bad voltage regulator on coil driver.  Entire unit replaced (no spare voltage regulator available.) No funny behavior seen on Current monitor.

LHO aLog 28948 -- 9 Aug: Original Coil Driver replaced (with replaced voltage regulator) but no excitation drive experiment done to confirm good behavior.

Today, drove Coil Driver w/ 3000 Ct 0.05 Hz sine, I_INMON responds to greater than 110 counts with no ill behavior observed, see attached.  Before repair, the I_INMON reversed and spiked to very large output (340cts) when the current reading hit 50-60 counts.  This suggests the coil driver is back to nominal behavior.  And, there have not been any ground motion events where ITMX was the only platform which tripped.

Deem this problem fixed and will move FRS 5948 to pending and recommend closure.