In the last couple days, as the IMC ringdowns have been going on, we have noticed that the MC is behaving bad. Misaligning, drifting, etc.
Gautam told me a horror story about him, Koji, and melted wires inside the sat boxes.
I said, "Its getting too hot in there. So let's take the lids off!"
So then we:
- Removed the lid (only 4 screws were still there)
- cut off some of the shield - ground wires and insulated them with electrical tape
- squished the IDC connectors on tightly
- left it this way to see if MC would get better - certainly the painfully hot heatinks inside the box were now just 110 F or so
After some minutes, we saw no drifting. So maybe my theory of "hot heatsink partially shorting a coil current to GND through partially melted ribbon cable" makes sense? IF this seems better after a month, lets de-lid all the optics.
Let's look at some longer trends and be very careful next to MC2 for the next 3 days! I have put a dangerous mousetrap there to catch anyone who walks near the vacuum chamber.
gautam: the grounding situation per my assessment is that the shield of all the IDC cables are connected to a common metal strip at 1X5 - but in my survey, I didn't see any grounding of this strip to a common ground. |