Keep it Running

Some equipment around the observatory is thirty or more years old. As you would expect, keeping it running can be a challenge.

A redesigned small signal PCB for an Inland Motor FCU-100-30 amplifier power supply
A redesigned small signal PCB for an Inland Motor FCU-100-30 amplifier power supply

There are two ways of dealing with this old equipment… Replacing it with something new is the preferred way. When it becomes difficult to locate spare parts, when it breaks down too often, just replace it with new gear. For much of the equipment this is the usual answer and is often a major part of the job.

Some equipment is not so easily replaced. When replacement would require wholesale redesign of a system it becomes more of a challenge. Sometimes the only choice is to keep that old gear running.

This is the case with our servo amplifiers. Twelve amplifiers supply the power that drives the telescope, one amplifier for each motor. Eight amplifiers and motors drive azimuth, four drive elevation. Three hundred and seventy tons moved by twelve relatively small DC motors. While much of the telescope control system was recently replaced, it was decided to keep the old servo amplifiers.

You might notice that these servo amplifiers are just a wee bit critical.

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Oops, a little too much power there…

How powerful is the K1 AO laser?

For someone who has lately been used to working around relatively harmless power levels, beams of a few milliwatts, this is a reminder that lasers are potentially very dangerous. With a milliwatt power level beam there is no danger in getting a hand in the beam, be mindful of your eyes, but otherwise not a lot of concern. This is vastly different, beam power here is measured in tens of watts… The bright yellow beam looks so innocent, appears so harmless. Give that beam a chance, a momentary slip, and it will burn you… badly.

Anything in the beam is at risk, even components we thought were robust enough to withstand the power levels. In this case a reflective ND filter that was to reflect most of the beam into a beam dump, allowing a small amount to continue up the beam train for use in alignments. So much for the ratings on the manufacturer’s data sheet, the beam punched through the coating and even started to melt the glass…

Burned Filter
A reflective ND filter burned through by the K1 AO Laser

SCRAM!

Shut it down! Shut it all down!

I get home from shopping in Kona and unloading a pile of groceries from Costco. Looking forward to a relaxing Saturday evening. That changed when I checked my e-mail.

Keck Webcam 4 Jun 2011
Several inches of snow in the Keck Telescope parking area on June 4th!
Oh joy…

Much of the systems on the summit are automated, up to and including sending e-mails when thing go wrong. The system works pretty well at letting the engineering staff know when attention is needed. The automated messages do tend to bomb a person’s inbox when it really goes bad.

Dozens of warning messages have flooded my inbox…

WARNING! K2AO temps are warm! dmrackTemp=45.42 degC, enclosTemp=37 degC

Ugly numbers indeed! 37°C is about 100°F in the AO electronics room. I have no choice… shut it down. Messages from MKSS indicate that the power lines have been hit by lightning and the power is out to the summit. The backup power is holding out, but the glycol cooling system is off. Without cold glycol flowing in the lines many of the rooms are without cooling systems to take away the heat generated by all of the computers and other electronics.

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