New Allen Telescope Array Development

Nov 14/15, 2018

2j was reporting 0 watts and 0 rpms for the Turbo pump. The cryo temp was >200k. The auto initialize function did not make any difference, it is supposed to re-initialize the turbo pump. It seemed to try, meaning on reset of the feed controller board the watts would jump up to 77 and the rpm would be at ~60,000, but it would wind down and in 10 minutes be at 0 again.

Rob Spencer showed me a set of commands to try. After issuing these commands to 2j the turbo pump went up to 77 watts then back down, but this time it went down to 13 watts, which is good! The rpm is now at ~90,000 and the cryo is holding at 65K. THIS TOOK 8 HOURS to SETTLE DOWN AND ACHEIVE 65K.

One thing of note: after all this, the “TC” command to the feed controller board showed “65.0”, but the ata command “atagetcrotemp 2j” reported:

ant2j: Comm problem with Feed controller / Sunpower cooler controller - null

I fixed this by bringing the JSDA server on ant2j down then back up. That fixed it:

ataant@antcntl:~> ataantsyscntl -d 2j
ataantsyscntl -u 2j

After this, I went back to tumulus:

obs@tumulus:~/jrichards 08:20:09 > atagetcryotemp 2j
ant2j  65.0

It now seems 2j is back in action!

You should check some set-up values.

command               response

p010                          1
p023                          111
p024                          000
p025                          000
p027                          001
p035                          003
p700                          000020
p701                          000090
p707                          010000
p708                          070
getfanpwm               100

If the values are correct (or even if you have to change them), one trick to help the vacuum recover is to just 
run the roughing pump on high over night or a few hours.

          24v & 48v ON.
          Shutdown the Cryo SET SSTOP=0
          Shutdown Turbo                 p023=000
          Roughing pump                   p024=009
          Roughing pump                   p035=007

 

Vacuum restart after high speed roughing.

          p035=003
          p024=000
          p023=111
          p010=000
          p010=1

The Turbo will restart & go through it normal run-time, if we got enough garbage out with the rougher it should be OK.

The normal start-up is to try to reach 90k rpms for about 20min, if it doesn’t make it the Turbo shuts down & waits 40min & try’s again.

After several attempt the Vacuum system will give up, “run-time error”.

If there is a vacuum leak we will never get to 90k rpms, if the Turbo stalls out at 15 or20K rpms, that an indicator that there is a leak.

Turbos stalling out at 30 to 50 or 60k rpms can with the about help get to 90k.