Subject: Re: [sloan-25mlog 3798] 2.5m obslog 20171214 (SJD 58102)
From: John Downey
Date: Fri, 15 Dec 2017 09:39:05 -0700
>=20
> Notes
> =3D =3D =3D
> 1. Scissors lift tripped the circuit breaker #26 on the first cart =
change.
>   Reseted. No time lost.
>   After the reset it doesn't work properly: it moves ~ 5 sec, then =
stops,
>   irrelevant to the standard loading positions.
>   It is doable to operate it, but please check in the day time.
>=20
>=20
> --
> During the cart change the scissors lift got stuck in the middle of =
moving.
> Motor was working on a very uneven way, mumbling, stopping and =
starting. In a
> few seconds it stopped. We've found that the mirrors are not relevant, =
nd found
> a tripped breaker (#28) for the lift. Reseted the breaker, the problem
> disappeared. After that the list started moving smoothly. No time lost =
for this
> problem.=20
We've not been able to repeat the problem this morning.
I don't think we can conclude that the mirrors were not relevant in this =
case, as in all other respects this sounds like a light curtain problem. =
 Although it is a mystery why the problem disappeared after tripping and =
resetting the breaker, I suspect that is coincidence.
We are working on plastic mirror mounts that should remove the =
temperature dependence of the light curtain if anything can.  I am =
hoping to have them installed during January engineering time.  If that =
does not correct these ongoing problems, I believe we will have to have =
an infrastructure discussion concerning the light curtain, whether we =
need it, what other options exist, and how long we need to maintain it =
(SDSS5 need to be in that discussion as well).=