[Rana Zach Koji]
We tracked down the MC locking issue to be associated with the power supply problem.
Replacing a fuse which had incomplete connection with the new one, the MC started locking.
We still have the MC autolocker not running correctly. This is solely a software problem.
We went down to the IOO electronics rack to investigate the electronics there. After spending
some time to poking around the test points of the MC servo board, we noticed that the -24V
power indicator on the MC demodulator module was not lit. In fact, Steve mentioned on Wednesday
that the -24V Sorensen supply had lower current than nominal. This actually was a good catch
but should have been written in the ELOG!!!
We traced the power supply wires for the crate and found one of the three -24V supply has no
voltage on it. Inspection of the corresponding fuse revealed that it had a peculiar failure mode.
The blown LED was not lit. The connection was not reliable and the -24V power supply was flickering.
We then replaced the fuse.This simply solved all of the issues on the MC servo board. The electronics
should be throughly inspected if it still has the nominal performance or not, as the boards were exposed
to the single supply more than a week. But we decided to try locking ability first of all.
Yes, we now can lock the MC as usual.
Now the newly revealed issue is MC autolocker. It was running on op340m but op340m does not want to run it now.
It should be closely investigated.
Also turning on WFS unlocks the MC. Currently the WFS outputs are turned off.
We need usual align MC / check spot position / adjust WFS QPD spots combo.