Yesterday during Maintenance, at 17:11:22UTC, there was a TCSY laser output off verbal alarm.  Patrick ran some trends, and Betsy took a look, and neither found a reason for TCSY to have tripped off.

Betsy and I went out and looked at, and reset, the laser controller, and the teperature LED was light up, however no temperature signals had gone high or low.  We reset with the key and pushed the Gate button, which restored TCSY to it's nominal configuration.

Attached are multiple plots of TCSY channels, various time frames, and from these I can see that something changed about 400 seconds before the verbal alarm, however it's not clear how these 400 second changes would cause the laser to trip off.  In the last 70 seconds before the verbal alarm, there's a very small glitch on H1:TCS-ITMY_CO2_PWR_SUPPLY_V_OUTPUT at -20 seconds from 0, and the glitch is barely noticable but may hold a clue.  At -60 seconds there's a jump in H1:TCS-ITMY_CO2_PWR_SUPPLY_V_OUTPUT, again, very small.  At -55 seconds there's a glitch in H1:TCS-ITMY_CO2_LSRPWR_MTR_OUTPUT and H1:TCS-ITMY_CO2_RIN_OUTLOOP_OUTPUT (though I'm not sure the TCS ISS is currently used).

No obvious reason for the TCSY laser to trip off.

Related to Jeff Kissel's alog about Maintenance Recovery: alog 51561

PLOTS:

1. time zero set to when gains started changing more rapidly, about 1200 seconds total
2. a longer time scale, about 30000 seconds, showing that rapid changes are not that unusual
3. an even longer time scale, about 500000 seconds, as a reference
4. the last 70 seconds before the laser trips off, features described above