The ALS laser (Prometheus 2143A) is in a worse situation.

Yokogawa, Sugimoto and Izumi.

Yesterday, we started playing the diode temperature for diodes A and B in order to search for some parameter region where the laser runs without shutting itself down (5775). At the beginning, it ran as usual -- the diode injection current was able to reach 2.0 A with no issues while reaching 2.2 A made the laser unstable leading to a sudden shut-down in 10-20 min. We changed the diode temperature by some amount within +/-2deg in the morning and early afternoon. As we were doing so, we noticed at one point that the temperature guard indicators became red for diode A while B was orange. We have no idea what this color scheme is for and couldn't find any descriptions on the manual. 

The toughest thing is that power-cycling the laser controller doesn't reset the temperature guard indicator for A and it stayed red as far as we tried.

We are planning to have another look at it on the Monday to see if we can get back to the previous situation.