DEIMOS Maintenance Log

Purpose

This file documents all modifications and changes to DEIMOS which are noteworthy.

Change Log

CCD 1A and 1B video signal coax swap [2003-Aug-19]

Having determined that the SMA/SMB swap appeared to fix the intermittent dropped bit problem, Bob had Hector swap the video signal coaxes, thus introducing a second swap which has the effect of undoing the SMA/SMB swap of two weeks ago. The next effect is that the output images are back to normal. See this document for further details.

CCD1 SMA/SMB connector swap [2003-Aug-05]

We have been having occasional problems with dropped bits on CCD 1A. To diagnose the source, Bob Kibrick swapped the SMA/SMB connectors on CCD1. This will swap the data in the resulting output image.

Ne lamp replaced [2003-Jul-30]

Replaced dim neon lamp.

DEIMOS Guider Shutter Repair [2003-May-07]

Replaced the guider shutter with p/n 2000734. Of the three shutters that were tested this is the only one that worked like shutters should. The voltage that opens the shutter is 14vdc, however, the voltage fluctuates anywhere from 8vdc to 14vdc. More tests are needed on the shutters that have the star shape pattern.

Dewar Filter WHeel Repair [2003-Jan-07]

Filter wheel quit rotating during a reconfig. Removed panels and found the motor spur gear slipped on the motor shaft to disengage the filter wheel. Repositioned the spur gear, R&R the set screw to apply Lock-Tite blue, and reinit the stage. Stage appears to be working ok.

Cleaned Slitmask Cassette [2002-Oct-31]

Rodriguez and Wagner performed the following service as requested except for using air. Dust was excessive and it was felt that contaminating the optics was highly probable.

Recommend modification to stage to allow easy removal of cassette for cleaning outside of instrument. Modification would involve changing blind bolts to accessable bolts where cassette attaches to actuator plate.

Replaced Failed Guider Shutter [2003-Oct-07]

Removed the filter wheel to inspect the shutter. Verified that the shutter was opening partially and needed to be replaced or secured open. After inspecting the filter wheel assembly, the decision was made to remove the shutter. In order for this to happen, one of the two filter wheel plates needed to be removed. Remove the filter wheel plate closest to the filter wheel. Removed and replaced the old shutter (p/n 04l214-6v; s/n 9913243) with a new shutter (p/n 04l214-6v; s/n 9913245). This was the ESI spare shutter. Needed to replace the 6vdc cable in order to install the DEIMOS connector. Verified that the new shutter operated properly before installing on to the camera head. The filter wheel plate that was removed was not put back into the instrument. This should not effect any filter wheel or guider camera operations, and will facilitate replacing shutters in the future. Mounted the filter wheel and verified proper rotation. Installed camera access cover.

Install Pull-Up Resistors to Cure LED Problem [2002-Sep-24/25]

Partial Implemented ECR 255. Verified TV filter stage and TV focus had the pull-up resistors installed. Modified Grating select stage , slitmask stage , and Slitmask cassette environment sense control box. with 1K pull-up resistors. Verified operation. On-going.

Completed implementation of ECR 255. Installed pull-up resistors in the CCD focus and translatiion stages, filterwheel stage, grating tilt #3 stage, and grating tilt #4 stage. Functional check good.

Slitmask Cassette Repair [2002-Sep-13]

Troubleshoot DEIMOS problem with slitmask juke box jamming. We weren't able to move slit mask assembly. Found grating cover was missing a screw and dismounted from its normal position. Screw was found inside instrument. The cover was then caught against juke box during moves. The grating cover was bent from the incident. The cover was bent back and reinstalled properly with locktite. Slitmask mechanism was then moved mechanically and verified to be operational. Instrument Specialist and Astronomers are informed of the situation. Pictures of grating cover forwarded to G. Wirth.

During troubleshooting, metal filings were removed from the brass guide rollers in front of the slit box mechanism. We also found leaky glycol fitting at the guide camera. Installed teflon on fitting and verified no leaks.

Guider Repair [2002-Aug-11]

Continued from previous day

The key was that we discovered that one of the boards in the head, which we found out today was the serial clock board, could be swapped with the spare even though they were different versions. It made sense to swap this since the original error was a serial clock error. We didn't do it Saturday because we didn't know if we could swap different version boards. Once the swap was made, the camera worked.

In order to install the camera we discovered the filter wheel is outfitted with a quick disconnect so the filters can be kept safe while the filter wheel mechanism goes in. After the camera was all hooked back up together, turned on the glycol flow and took good images. Sandy and Mason aligned the camera. It is in proper focus when viewing from the front the camera is rotated to the maximum clockwise position that the slop in tne mounting bolts allow.

Other Stuff to be aware of that we did and checked --

removed air so that we could manually move hatch up and down. air reconnected.
removed hatch b. replaced hatch b.
removed front two lower quarter panels on snout with guider camera oriented horizontal on lower half of snout. panels were replaced.
covered window with low lint optical cloth. removed cloth.
the hatch covers around the PXL CEU2 controller were removed. hatch covers replaced.
DEIMOS was undefined, then later defined.

The RBC PXL head is being brought down to be sent back for repair. Miguel has details.

Guider Repair [2002-Aug-10]

DEIMOS Guider is NOT functional. The guider will not be available for the rest of the DEIMOS run. Efforts should be made to form a backup observing plan.

Today's efforts were focused on removing the DEIMOS guider camera head and trying to get it or the spare head to work. We were unsuccessful.

The basic status is that last night's troubleshooting was aimed at isolating the failure. It was isolated to the DEIMOS PXL camera head. Because the camera head alignment was very difficult, the goal was to try to repair the DEIMOS camera head and put it back in with as little disrupt to alignment as possible.

A VERY arduous process was undertaken to get the camera head removed so we could inspect and swap boards. Thanks to Dave Cowley for the procedure. I did get a few pictures that should help. The following steps were taken --

drove tel up and over to NRT2/RT4 position
backed DEIMOS up to get access to front
rotated so hatch was horizontal on lower half of disk
locked DEIMOS
removed lower 2 arc panels on snout
removed unused side B hatch (dropped a washer in snout, didn't realize it wasn't tapped, could not locate washer, probably fell thru grating)
Tim put low lint cloth across back of window and cardboard to protect it.
Disconnected compressed air and bled lines in prep for removing 4" beam in front of snout.
Taped hatch closed.
Turned out we didn't need to remove beam to get camera and filter wheel out. Tim did need to fabricate two cut-off allen wrenches, though.
Unplugged filter wheel cables
Unplugged camera head cables except DB25 power cable which was screwed on.
Released mounting bolts from front (have pictures) and camera head and filter wheel with their respective mounting plates came out together. This step very awkward and difficult and somewhat risky. The filter wheel was separated from the camera head and stored in safe location. The camera head was still attached by the power cable and glycol lines, Removed power cable.
shutoff glycol to PXL
removed PXL QDs on cooling lines
unrouted PXL head cables to give enough slack to test camera outside side of snout.

This took about 4+ hours.

Once the camera head was out we proceeded to troubleshoot. There are 4 boards in the camera head. 3 of the boards are easily accessible, so we tried swapping them, one at a time, with the RBC guider camera head. This did not work -- same serial clock error. In order to try the fourth board, we had to de-mount the camera head from it's mounting plate.

When we got the fourth board out we realized they were different versions. Decided not to take a chance and jeopardize the CCD. Instead decided with Sandy Faber to try and put the RBC camera back together (what we were calling the spare) and try it in DEIMOS.

Configured RBC back to original configuration. Connected to DEIMOS controller thru DEIMOS cables and got a green light on the controller. Tried to take and image but got an error in kcamtest that pointed to a controller prom needing to be swapped. Swapped the PROM. This time no error.

At this point encountered a major irritation. Could not take images with kcamtest on huakini and couldn't get exceed to work from a PC. It works all the way up until you read out an image then it crashes. WE NEED TO FIX THIS.

Ran xguide instead since we knew PROM was compatible. Image read out but image had all zeroes. This same configuration was tried last night during troubleshooting and worked so something has failed between then and today. Most obvious thing was the video cable from head to controller since we know we read all zeroes when it becomes unplugged. Inspected and buzzed cable. All ok. Tried a spare set of cables, still all zeroes.

It could be that during the swapping of camera head boards that one of the boards were damaged or the boards got mixed up. Opened up the spare camera head and double checked serial numbers again...all correct as we had assumed. Last gasp was to try the video board from the DEIMOS head in the spare head. This time we did not get all zeroes, but we did get an awful looking image with big stripes of all zeros and stripes of a few hundred counts. Anyway totally not functional. Saved a cam image for later analysis.

At this point Sandy/Greg decided to observe without the guider.

We've put the front and rear hatches and panels back. Both guider heads and filter wheel are removed and in the instrument lab. The inside of the snout was checked and double checked. The low lint cloth was removed from the window. Air is back on, hatch works, PXL glycol left off. DEIMOS is defined, fill complete. Glenn is in the process of changing a grating for tonites modified observing plan.

We did not have time to put metal tape along all the seams for light tightness along the hatch covers.

The following things were taken to the instrument lab --

Both guider camera heads. (I will ask Glenn to cart them down tomorrow assuming we have a less busy day tomorrow.)
The filterwheel assembly
guider mounting plates for RBC and DEIMOS
cables and hardware

Huge thanks to Bill Healy, he's been here with me since 9am. Thanks also to Saloga for helping demount the camera and to Glenn for helping out and staying late. Thanks to Jason, Tom, Steve and Glenn for staying late last night to troubleshoot. Sorry to the observers, I really don't think we could have done much more.

	DEIMOS Maintenance Log
DEIMOS Home Page NEWS Config form Slitmask database DEIMOS temps (internal) Index Keck Instrument Ready? Archive (KOA) Observer Home Page Tel Schedule Instruments Home Keck Home Observing Info ToO Policies Weather MK Forecast CFHT SkyProbe MK Seeing CFHT Cloudcam Summit Cams Keck Cloud Cams Planning Tools Starlist Tool Finding Charts IRSA Finder Charts Observing Planning Tool Offset/PA Tool Contact Us Contact Info Post-Observing Comment Form WWW Keck Web Site	Purpose This file documents all modifications and changes to DEIMOS which are noteworthy. Change Log CCD 1A and 1B video signal coax swap [2003-Aug-19] Having determined that the SMA/SMB swap appeared to fix the intermittent dropped bit problem, Bob had Hector swap the video signal coaxes, thus introducing a second swap which has the effect of undoing the SMA/SMB swap of two weeks ago. The next effect is that the output images are back to normal. See this document for further details. CCD1 SMA/SMB connector swap [2003-Aug-05] We have been having occasional problems with dropped bits on CCD 1A. To diagnose the source, Bob Kibrick swapped the SMA/SMB connectors on CCD1. This will swap the data in the resulting output image. Ne lamp replaced [2003-Jul-30] Replaced dim neon lamp. DEIMOS Guider Shutter Repair [2003-May-07] Replaced the guider shutter with p/n 2000734. Of the three shutters that were tested this is the only one that worked like shutters should. The voltage that opens the shutter is 14vdc, however, the voltage fluctuates anywhere from 8vdc to 14vdc. More tests are needed on the shutters that have the star shape pattern. Dewar Filter WHeel Repair [2003-Jan-07] Filter wheel quit rotating during a reconfig. Removed panels and found the motor spur gear slipped on the motor shaft to disengage the filter wheel. Repositioned the spur gear, R&R the set screw to apply Lock-Tite blue, and reinit the stage. Stage appears to be working ok. Cleaned Slitmask Cassette [2002-Oct-31] Rodriguez and Wagner performed the following service as requested except for using air. Dust was excessive and it was felt that contaminating the optics was highly probable. Recommend modification to stage to allow easy removal of cassette for cleaning outside of instrument. Modification would involve changing blind bolts to accessable bolts where cassette attaches to actuator plate. Replaced Failed Guider Shutter [2003-Oct-07] Removed the filter wheel to inspect the shutter. Verified that the shutter was opening partially and needed to be replaced or secured open. After inspecting the filter wheel assembly, the decision was made to remove the shutter. In order for this to happen, one of the two filter wheel plates needed to be removed. Remove the filter wheel plate closest to the filter wheel. Removed and replaced the old shutter (p/n 04l214-6v; s/n 9913243) with a new shutter (p/n 04l214-6v; s/n 9913245). This was the ESI spare shutter. Needed to replace the 6vdc cable in order to install the DEIMOS connector. Verified that the new shutter operated properly before installing on to the camera head. The filter wheel plate that was removed was not put back into the instrument. This should not effect any filter wheel or guider camera operations, and will facilitate replacing shutters in the future. Mounted the filter wheel and verified proper rotation. Installed camera access cover. Install Pull-Up Resistors to Cure LED Problem [2002-Sep-24/25] Partial Implemented ECR 255. Verified TV filter stage and TV focus had the pull-up resistors installed. Modified Grating select stage , slitmask stage , and Slitmask cassette environment sense control box. with 1K pull-up resistors. Verified operation. On-going. Completed implementation of ECR 255. Installed pull-up resistors in the CCD focus and translatiion stages, filterwheel stage, grating tilt #3 stage, and grating tilt #4 stage. Functional check good. Slitmask Cassette Repair [2002-Sep-13] Troubleshoot DEIMOS problem with slitmask juke box jamming. We weren't able to move slit mask assembly. Found grating cover was missing a screw and dismounted from its normal position. Screw was found inside instrument. The cover was then caught against juke box during moves. The grating cover was bent from the incident. The cover was bent back and reinstalled properly with locktite. Slitmask mechanism was then moved mechanically and verified to be operational. Instrument Specialist and Astronomers are informed of the situation. Pictures of grating cover forwarded to G. Wirth. During troubleshooting, metal filings were removed from the brass guide rollers in front of the slit box mechanism. We also found leaky glycol fitting at the guide camera. Installed teflon on fitting and verified no leaks. Guider Repair [2002-Aug-11] Continued from previous day The key was that we discovered that one of the boards in the head, which we found out today was the serial clock board, could be swapped with the spare even though they were different versions. It made sense to swap this since the original error was a serial clock error. We didn't do it Saturday because we didn't know if we could swap different version boards. Once the swap was made, the camera worked. In order to install the camera we discovered the filter wheel is outfitted with a quick disconnect so the filters can be kept safe while the filter wheel mechanism goes in. After the camera was all hooked back up together, turned on the glycol flow and took good images. Sandy and Mason aligned the camera. It is in proper focus when viewing from the front the camera is rotated to the maximum clockwise position that the slop in tne mounting bolts allow. Other Stuff to be aware of that we did and checked -- removed air so that we could manually move hatch up and down. air reconnected. removed hatch b. replaced hatch b. removed front two lower quarter panels on snout with guider camera oriented horizontal on lower half of snout. panels were replaced. covered window with low lint optical cloth. removed cloth. the hatch covers around the PXL CEU2 controller were removed. hatch covers replaced. DEIMOS was undefined, then later defined. The RBC PXL head is being brought down to be sent back for repair. Miguel has details. Guider Repair [2002-Aug-10] DEIMOS Guider is NOT functional. The guider will not be available for the rest of the DEIMOS run. Efforts should be made to form a backup observing plan. Today's efforts were focused on removing the DEIMOS guider camera head and trying to get it or the spare head to work. We were unsuccessful. The basic status is that last night's troubleshooting was aimed at isolating the failure. It was isolated to the DEIMOS PXL camera head. Because the camera head alignment was very difficult, the goal was to try to repair the DEIMOS camera head and put it back in with as little disrupt to alignment as possible. A VERY arduous process was undertaken to get the camera head removed so we could inspect and swap boards. Thanks to Dave Cowley for the procedure. I did get a few pictures that should help. The following steps were taken -- drove tel up and over to NRT2/RT4 position backed DEIMOS up to get access to front rotated so hatch was horizontal on lower half of disk locked DEIMOS removed lower 2 arc panels on snout removed unused side B hatch (dropped a washer in snout, didn't realize it wasn't tapped, could not locate washer, probably fell thru grating) Tim put low lint cloth across back of window and cardboard to protect it. Disconnected compressed air and bled lines in prep for removing 4" beam in front of snout. Taped hatch closed. Turned out we didn't need to remove beam to get camera and filter wheel out. Tim did need to fabricate two cut-off allen wrenches, though. Unplugged filter wheel cables Unplugged camera head cables except DB25 power cable which was screwed on. Released mounting bolts from front (have pictures) and camera head and filter wheel with their respective mounting plates came out together. This step very awkward and difficult and somewhat risky. The filter wheel was separated from the camera head and stored in safe location. The camera head was still attached by the power cable and glycol lines, Removed power cable. shutoff glycol to PXL removed PXL QDs on cooling lines unrouted PXL head cables to give enough slack to test camera outside side of snout. This took about 4+ hours. Once the camera head was out we proceeded to troubleshoot. There are 4 boards in the camera head. 3 of the boards are easily accessible, so we tried swapping them, one at a time, with the RBC guider camera head. This did not work -- same serial clock error. In order to try the fourth board, we had to de-mount the camera head from it's mounting plate. When we got the fourth board out we realized they were different versions. Decided not to take a chance and jeopardize the CCD. Instead decided with Sandy Faber to try and put the RBC camera back together (what we were calling the spare) and try it in DEIMOS. Configured RBC back to original configuration. Connected to DEIMOS controller thru DEIMOS cables and got a green light on the controller. Tried to take and image but got an error in kcamtest that pointed to a controller prom needing to be swapped. Swapped the PROM. This time no error. At this point encountered a major irritation. Could not take images with kcamtest on huakini and couldn't get exceed to work from a PC. It works all the way up until you read out an image then it crashes. WE NEED TO FIX THIS. Ran xguide instead since we knew PROM was compatible. Image read out but image had all zeroes. This same configuration was tried last night during troubleshooting and worked so something has failed between then and today. Most obvious thing was the video cable from head to controller since we know we read all zeroes when it becomes unplugged. Inspected and buzzed cable. All ok. Tried a spare set of cables, still all zeroes. It could be that during the swapping of camera head boards that one of the boards were damaged or the boards got mixed up. Opened up the spare camera head and double checked serial numbers again...all correct as we had assumed. Last gasp was to try the video board from the DEIMOS head in the spare head. This time we did not get all zeroes, but we did get an awful looking image with big stripes of all zeros and stripes of a few hundred counts. Anyway totally not functional. Saved a cam image for later analysis. At this point Sandy/Greg decided to observe without the guider. We've put the front and rear hatches and panels back. Both guider heads and filter wheel are removed and in the instrument lab. The inside of the snout was checked and double checked. The low lint cloth was removed from the window. Air is back on, hatch works, PXL glycol left off. DEIMOS is defined, fill complete. Glenn is in the process of changing a grating for tonites modified observing plan. We did not have time to put metal tape along all the seams for light tightness along the hatch covers. The following things were taken to the instrument lab -- Both guider camera heads. (I will ask Glenn to cart them down tomorrow assuming we have a less busy day tomorrow.) The filterwheel assembly guider mounting plates for RBC and DEIMOS cables and hardware Huge thanks to Bill Healy, he's been here with me since 9am. Thanks also to Saloga for helping demount the camera and to Glenn for helping out and staying late. Thanks to Jason, Tom, Steve and Glenn for staying late last night to troubleshoot. Sorry to the observers, I really don't think we could have done much more.
Last modified: 07/10/2020 05:20 Send questions or comments to:DEIMOS Support