STT-8300M guide chip problem

Discussion in 'STT Series' started by jliles01, Nov 5, 2016.

  1. jliles01

    jliles01 Cyanogen Customer

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    We used DriverChecker(newest version) and updated both the drivers and the firmware for our STT-8300M w/FW8G-STT today. All indications were that both updates were successful. Now we have a problem that we didn't have before. We have always had a problem with the guide chip intermittently losing the guide star for a couple of seconds. Rarely was that bad enough to abort the image, but it did happen sometimes. We are using CCDOPS, and had no problems before the update.

    We found a bright star in the imaging chip. Went to start guiding and no guide stars seen. We increased the exposure repeatedly all the way to 10 seconds. We did move the scope around looking for stars. We finally swapped chips and used both "Focus" & "Grab" with no success. All images with the guide chip looked basically like a dark frame, dark with noise.

    We finally hooked up our light box we use for flat fields. the main chip was blasted out to max, the guide chip was still dark. We changed from "internal" guide chip to "external", no change. Back to "internal", no change. These were still at 10 sec exposures.

    Suddenly, it started working. There were stars in the guide chip. We decided to go through the procedure from the FW8G-STT manual to adjust the position of the Pick-off Mirror and focus the guide chip. We got that done and locked down the Pick-off Mirror. We took another image using the guide chip, and it went back to dark w/noise. No stars, whereas before their were multiple stars in the image. We tried the light box again, still dark.

    All of the images using "Focus" & Grab" were dark w/a little noise (like a dark frame). Most of the "dual-chip" images were the same for the guide chip. The main chip always saw stars. But a few times, the "dual-chip" image was very strange. I saved one that I could send. The guide chip was totally black for about 90% of the bottom of the chip, with the top 10% "dark w/noise".

    Another problem we had was with the downloads. A few times, while downloading the image from the guide chip using "Grab" or ""dual-chip" , it would get extremely slow. This only happened when the guide chip was used. And it never happened in "Focus" or using the main chip alone.

    I don't know if the updates had anything to do with this. And I saw an earlier post from the beginning of 2015 about bad HDMI cables. We purchased the camera & filter wheel Dec 2014 and it was delivered Apr 2015. But have not had these problems until now.

    Like I said, I have the "dual-chip" image that I could send. It's FITS, and about 30Mb but can be converted. Also, I'm home now and don't have easy access to the camera & computer at our observatory. It would take a few days to try anything or get more info. I know on my home computer, I use CCDOPS Ver. 5.57 Build 3-NT. We try to keep the same version here and at our observatory, but I can't say for sure it is. I didn't think to check that before I left tonight.

    Thank You.
     
  2. jliles01

    jliles01 Cyanogen Customer

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    I just read this thread by Keith Shank on Sep 27, 2016: http://forum.diffractionlimited.com/threads/stt8300-fw8gstt.2662/.

    The symptoms sound exactly like what is happening to us. In the "Dual Chip" image we took and saved, it does look like a shutter is in front of about 90% of the guide chip. I am going to check this to see if our shutter is sticking. But it doesn't explain all of our "no star on the guide chip" ima

    But something else in that thread I didn't understand. Doug said the guide chip needs to be set as EXTERNAL. We've been using the camera and imaging for over a year. We have some good images. But we've had our camera set up, via CCDOPS, with the guide chip set to INTERNAL and it's been working & guiding. It was set on INTERNAL when we started yesterday. We tried changing it with no success.

    We will do some more experimenting.
     
  3. jliles01

    jliles01 Cyanogen Customer

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    Finally figured out how to upload a file here. This is the Dual Chip image I was referring to.

    Well, thought I did. Uploading images doesn't seem to work. Progress bar goes to 100% and just sits there. Click POST & no attachment in my reply.
     
    Last edited: Nov 6, 2016
  4. jliles01

    jliles01 Cyanogen Customer

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  5. Colin Haig

    Colin Haig Staff Member

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    Hi James, I successfully downloaded your images from DropBox. There is some data in the guider chip area of the dual chip fits files. What happens if you just grab a bunch of images from the guide chip, on its own?
     
  6. jliles01

    jliles01 Cyanogen Customer

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    I'll try to do that. May take a couple of days. We took plenty last night, but didn't save any. As to what happens, they look like dark frames, no stars but a little noise. And as I said, it stopped working, then it started working, then it stopped again. While it was working, 4 or 5 fairly bright stars in the field. Did not move the scope, change exposure times, change settings, or clouds rolled in between the working & not-working images.

    Is it possible the shutter is getting stuck partially open? Would part of the image that's uncovered look normal and the rest look like a dark frame? When I look at the very top of the dual chip image it looks like the top of the guide chip/image is starting out normal, then the bottom 90% is covered.
     
    Last edited: Nov 6, 2016
  7. jliles01

    jliles01 Cyanogen Customer

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    Well, the last 2 nights have been strange with our guide chip.

    Last night, it was cloudy so we set the light box on the scope to use as a light source. Using CCDOPS. The first couple of images at .12 seconds were dark, then the guide chip started working and each image looked like a normal Flat Field. We used both GRAB and SELF-GUIDE. I saved some images from both, the SELF-GUIDE images being the guide chip frame waiting for us to pick a guide star. We did this using both the INTERNAL & EXTERNAL setting for the guide chip. They both worked, but it would flip the image left and right. There was a dust spot that would move from one side of the frame to the other. So we thought we had it working again, but as I said, cloudy so no images or guiding.

    Tonight, it was really strange. It was clear and we had the scope on a star and centered in the imaging chip. Guide chip showed no stars. We tried this and that, then came across a sequence that would get the guide chip to show stars for one (1) frame.

    1) Take a 2 second Dual Chip image. Star in imaging chip, no stars in guide chip.
    2) Take a 2 second Grab on the imaging chip w/no dark frame. Star in image.
    3) Switch chips, take a 2 second Grab on the guide chip w/no dark frame. Multiple stars in the image!
    4) Take another 2 second Grab on the guide chip w/no dark frame. No stars in image again.

    We went through this same sequence 6 or 7 times. It worked the same every time! We tried this using both settings for the GUIDE CCD, Internal & External. That made no difference, it worked the same with both. We had the scope tracking, and every time we checked the star was in the same place on the imaging chip. We were using CCDOPS. We randomly tried taking images with the guide chip using Grab & Self-guide, images always dark & no stars. But every time we went through the above sequence, it worked the same way.

    2 second dark frame with guide chip
    Image 1.FIT

    2 second light frame with guide chip
    Image 2.FIT

    2 second light frame with guide chip AFTER taking a 2 second light frame with imaging chip
    Image 3.FIT

    .12 second flat field from previous night. GUIDE CCD set to External
    Image 5.FIT

    .12 second flat field from previous night. GUIDE CCD set to Internal
    Image 6.FIT

    .12 Self-Guide image saved while waiting to pick a guide star. GUIDE CCD set to External
    Image 7.FIT

    .12 Self-Guide image saved while waiting to pick a guide star. GUIDE CCD set to Internal
    Image 8.FIT

    Dual Chip Image. Too large for here. https://www.dropbox.com/s/f1cko5xw1ntfs6m/Image 4.JPG?dl=0

    Drivers & Firmware
    Firmware.jpg
    Drivers.jpg
     

    Attached Files:

    Last edited: Nov 10, 2016
  8. Colin Haig

    Colin Haig Staff Member

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    James, I had a fast look at your images. Can you upload the FITS of Image4 to dropbox?
    I noticed that some of your images (1,2,3) are taken with the IR filter in place, and the rest are with the Blue (5,7). Also, I see some have autodark subtract (7), and others dont.
    A consistent set makes it better to debug what's going on. Also, they don't reflect the sequence you describe in your tests.

    Image 3 has a note that says "NOTE = 'Local time:11/10/2016 at 18:33:59.000. took dual, took main grab' "
    It looks like the only good star exposure. What's that NOTE about?
    Images 7,8 seem like flats. Are they? If not, where's the illumination coming from?

    Have you checked for hardware weirdness? e.g. had a look at the camera on the workbench, and seen if the shutter is opening /closing for the guide exposures? And is the filter wheel turning when the exposure is running, or does it complete turning?
     
  9. jliles01

    jliles01 Cyanogen Customer

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    1) Take a 2 second Dual Chip image. Star in imaging chip, no stars in guide chip. Image 4 jpg. https://www.dropbox.com/s/vv0iztjbfgu2hw7/Image 4.FIT?dl=0
    2) Take a 2 second Grab on the imaging chip w/no dark frame. Star in image. Did not save Imaging Chip frames
    3) Switch chips, take a 2 second Grab on the guide chip w/no dark frame. Multiple stars in the image! Image 3
    4) Take another 2 second Grab on the guide chip w/no dark frame. No stars in image again. Identical to Image 2. I did not save the particular image during this step.

    We started changing the filters, then realized on the FW8G-STT the guide chip is in front of the filters, so the filters are not in play.

    I started to use that "Note" thing, then decided not to. But Image 3 is the ONLY time the Guide Chip saw any stars. Image 3 was taken during step 3 in the sequence I described above.

    Images 5 & 6 were taken Dark Frame NONE with Grab using the Guide Chip. The only difference being the Internal & External setting in Setup for the Guide CCD. So they were just like taking a Flat Field.

    Yes, Images 7 & 8 look like Flats. Basically they were, but not intended that way. They were taken the previous night when the Guide Chip seemed to be working properly. It was total cloud cover. We were using the light box so the camera would see something. They were during a Self-Guide session and those images were saved after the camera took a light frame with the Guide Chip and was waiting for us to choose a guide star. I saved the image, then aborted the rest of the Self-Guide session instead of picking a guide star and clicking Resume. Images 7 & 8 were done the same way, the only difference being the Internal & External setting in Setup for the Guide CCD. During a Self-Guide, the camera automatically takes a Dark frame for the guide chip. It does the same for a Dual Chip image for both chips.

    Image 1 IS a Dark Frame ONLY taken with Grab using the Guide Chip. Image 2 is a Dark Frame NONE taken with Grab using the Guide Chip. They look almost identical. That's what makes me think of the shutter not opening.

    I have the camera here at home and getting ready to hook it up to my computer. I do not have a scope to put it on, so it will be a desktop test. I plan to look inside and try to see the shutters operate.

    Thanks Colin
     
    Last edited: Nov 11, 2016
  10. Colin Haig

    Colin Haig Staff Member

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    Ok, that clears it up. So 5,6 and 7,8 are actual good images then. Which means the guide chip is seeing light, and it is getting downloaded properly.
    Agree with you that something not right with image 2, and seems like light not getting to the chip. Bench test should help you see what is happening.

    If that's not it, then another line of thinking (may be a red herring) - Do you have a focal reducer on the 8" LX200? Am wondering if light cone is a problem / focus of the guide chip is a problem.
     
  11. jliles01

    jliles01 Cyanogen Customer

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    No focal reducer. 5,6 & 7,8 were taken 2 nights ago, and it seemed to be working. 1,2, & 3 were taken last night.

    Bench testing now. I can see the guide chip shutter open & close. But it's not consistent. I have it set up to take Dual Chip images and Auto Update. There are times the Guide Chip shutter opens and other times it doesn't. But no matter whether it's open or closed, I seem to get the same type of images. It's almost like the entire Guide Chip isn't recording an image during a Dual Chip session. I'm going to try using Grab next with the GuideChip.

    Also, When I have the pick-off mirror locked down, that's when the shutter doesn't always open. When it's unlocked, the shutter seems to always open. But the images don't change between the 2. And I can hear a difference in the sound the shutter makes between Locked & Unlocked.

    Here are 3 examples of the Dual Chip Images I'm getting today. They are slightly different, but show up randomly.
    https://www.dropbox.com/s/hxbccxj6mzx4m34/2 sec dual 1.FIT?dl=0
    https://www.dropbox.com/s/3bamucxmcgrvqmq/2 sec dual 2.FIT?dl=0
    https://www.dropbox.com/s/vq4ts1uzctbo422/2 sec dual 3.FIT?dl=0
     
  12. jliles01

    jliles01 Cyanogen Customer

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    Using Grab, the Guide Chip images look more like their supposed to compared to the Dual Chip images. I'm beginning to think using Dual Chip may not be a good test. Maybe because of different sensitivities of the chips, I don't know. Thee seems to be a lot of differences in the Dual Chip images. Some show the entire Guide Chip, some show just a little strip at the top, some show all black. And the Imaging Chip is always correct.

    Here are examples of Grab images. Using Grab, the Guide Chip shutter always opened when the pick-off mirror was unlocked, and it NEVER opened when the pick-off mirror was locked. BUT, when it was locked, I could still hear a little click, like it tried to open.
    Image 9 2 sec Grab, light only, no dark. Mirror locked, shutter did NOT open.
    Image 9.FIT

    Image 10 2 sec Grab, light only, no dark. Mirror unlocked, shutter DID open.
    Image 10.FIT

    Image 11 2 sec Grab Light & Dark. Mirror unlocked, shutter DID open.
    Image 11.FIT

    Image 12 2 sec Grab Light & Dark. Mirror locked, shutter did NOT open.
    Image 12.FIT
     

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  13. Colin Haig

    Colin Haig Staff Member

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    If you have the mirror locked, you're saying the shutter does not open.
    Two thoughts:
    1. can you check the status LEDs on the side of the camera when this happens? Am wondering if there is a power supply low-voltage problem. e.g. is the second LED next to the green one on, and what color?
    2. Am wondering if there is a mechanical problem, like something misaligned / caught inside the FW8G-STT. Have you considered opening up the filter wheel and seeing what's going on in there, in case something is amiss?
    You might have to contact Bill Lynch at SBIG repair for help.
     
  14. jliles01

    jliles01 Cyanogen Customer

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    Yes, mirror locked, shutter doesn't open. And I just noticed, if the mirror lock set screw is at certain positions, the shutter will open partially. I can visually see it partially open sometimes.

    The second LED is NOT on. I am using the power supply that came with the camera. Gonna look in the manual for the LEDs.

    I agree, it might be a mechanical problem. But it just seems coincidental. We used the camera the first part of the year with no problem. Almost sure we had the pick-off mirror locked. We set up about 3 weeks ago for the 1st time since May. We had a comm problem with the Scope, which took a week to correct. While we were waiting, we updated the camera drivers & firmware. We did NOT USE the camera immediately before the update, so I don't know if it had any problems then. I know it didn't last May. The problem showed up after the update. And I remember Doug saying, in another post, that one of the updates included something about "de-coupling the shutters".

    And like I said before, the Dual Chip views just don't look right, with or without the mirror locked. Even when I could visually see the Guide Chip shutter open during a Dual Chip view, the pictures didn't seem to change. But they do change during Grab with the shutter open or stuck.

    I'm just a little worried about voiding any warranty, if any, in opening up the filter wheel. I am mechanically/electronically inclined, so wouldn't have a problem in that respect.

    Some of the testing results just don't seem to make sense though.

    Colin, I want to thank you for the help. I will keep posting here about it when I find something new.
     
  15. Doug

    Doug Staff Member

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    You can open the lid to look at the inside of the wheel without any impact on warranty. After all, you have to do that to install filters.
     
  16. jliles01

    jliles01 Cyanogen Customer

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    Haven't done that yet. But just looking in the "nosepiece" side, I'm not sure If I can see anything of the pick-off mirror/guide chip sections.

    I've taken a couple of videos of me taking Dual Chip auto Update views. Gonna download from my cellphone and get them into Dropbox.

    Edit: You're right. I should be able to see it.

    Edit 2: 200+ MB video files. Gonna take an hour to upload to Dropbox.

    Edit 3: While the videos are uploading, I wanted to report some other symptoms.

    While taking the videos, I noticed times when the status window would say "taking dark frames" and the guide shutter would be open. Other times the status window would say "taking light frame" and the shutter would be closed. this seemed to happen both with mirror locked & unlocked. I don't know how up-to-date & "real life" that status window is.
     
    Last edited: Nov 11, 2016
  17. jliles01

    jliles01 Cyanogen Customer

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    Last edited: Nov 11, 2016
  18. jliles01

    jliles01 Cyanogen Customer

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    We got the camera guiding again. The guide chip is seeing stars.

    We focused the main chip, then focused the guide chip. But when I locked down the guide chip, the stars disappeared. Shutter not opening. Unlocked the guide chip, stars came back. Left it unlocked.

    We do have a new problem that just showed up tonight. I will start a new thread for it.
     

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