Fixing a Stuck ESI Hatch

Sometimes the ESI hatch has failed to make either its open or closed position. Often it is actually within a small distance of the position, but it is difficult to guarantee this. It is also not easily diagnosed using images.

Make sure you are clicking "Move"

First of all, make sure that you are clicking on the "Move" button on the ESI GUI! Simply selecting "Closed" or "Open" from the pull-down menu will not actually move the hatch, it only expresses a desire to move it some time in the future!

If you want to try via keyword to move the hatch, open it with:

modify -s esi hatchpos = open

and close it with:

modify -s esi hatchpos = closed

If these commands do not work, proceed with the following...

Check the air pressure

• On kanaha as esieng, type "s airpwpsi". You should get a number near 50 PSI.

Fix without climbing onto the telescope

You can try to get the hatch to move by letting gravity help you:

• Move to a low elevation. (You can go to horizon if you wish, but 20° should be fine, too.)

• To CLOSE the hatch, move the rotator to ROTPPOSN = -5°.
  Try to close the hatch again.

• To OPEN the hatch, rotate to ROTPPOSN = -185°.
  Try to open the hatch again.

The sure fix

To visually inspect and/or manually help the hatch into position:

• Go to zenith (NOT horizon!).

• Set the rotator to ROTPPOSN = -45°.

• Climb onto the mirror cell. From this vantage point you can best see the ESI hatch, which is on the end furthest into the telescope, and you can reach it by hand.

• Keeping your hands well away from the hatch, have someone trigger the hatch in the desired direction (open or closed). If they report a failed move, you can carefully reach out to help the hatch in that direction.
  (The software activation charges the air cylinder in the appropriate direction, to help you out.)

• Report the circumstances of your repair (whether it was close to being in position, whether there seemed to be an air leak, etc.) in the night or day log.

• Have the person running the software confirm whether the GUI shows the hatch in the correct position now. (The "MOVE FAILED" phrase may still be lit up, but the graphic should be in the proper position.)

Notes:

December 1999
A seal was found to be leaking in the hatch cylinder. The cylinder was replaced and a new, more robust cylinder put on order.

ESI Master
27 December 1999