Loss of images after cooling turned on.

Discussion in 'Aluma Series' started by Tom Haugh, Apr 25, 2020.

  1. Tom Haugh

    Tom Haugh Cyanogen Customer

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    The last two clear evenings have started out poorly. After powering up my AL3200 I can take images up until the time I turn on cooling. At that time the output image is completely black without anything visible at all. It then becomes an exercise in power cycling, warm up/cool down iterations. Once I can get the camera to put out an image while cooling on, the camera works fine for the rest of the session. Is there a required order of operation that I am violating? Some sort of interlock? I am concerned this is a snowball starting down the hill.

    I am using the power supply and extension provided with the camera.

    Thanks,
    Tom Haugh
     
  2. Doug

    Doug Staff Member

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    That isn't something we have seen before. In fact I'm not sure how that can happen. The power supplies for the rest of the camera's electronics are completely independent of the cooler's.

    Are the images you get completely all zeros?

    One thing to try as an experiment - set the cooler setpoint high and then move it down gradually.
     
  3. Colin Haig

    Colin Haig Staff Member

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    Tom,
    What's the firmware version in the camera ?
    DLImaging driver version?
    What software program are you using and version?
    DL Config will give you the firmware version.
    Camera serial number would be good to know too.
    Thanks in advance.
     
  4. Tom Haugh

    Tom Haugh Cyanogen Customer

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    Further investigation looks like this camera is very sensitive to the CCD temperature, but not predictively so. Due to clouds I started the evening of the 25th with the scope pointed to my flat panel. The flat panel has a setting range of 0-255. A 1.2 second exposure at a setting of 75 gives me a adequate flat. With the cooling set to my normal -10C I was getting totally blank images. On a lark I started increasing the flat panel setting. At a setting of about 150 I noticed a couple of exposures had a smattering of individual pixels along the right edge. The Maxim Information window set on 'area' showed a maximum of between 45 and 70. However, the majority of the exposures read all 0's.

    I set the flat panel back to 75, set the cooling to warm-up and started taking images. The first image to show anything had a reported temp of 4.15C. It was not a good image though. It had a wide gradated bright horizontal band. The next image less than a minute later with a reported temp of 7.1C had a normal looking image. The skies finally cleared and I pointed to the star Regulus as the target and continued to take 1.2s images at different temps. Sometimes the star was visible sometimes not. I have a series of images taken during the hour long session. I can send them if you want.

    Last night, the 26th, was different. I could not get any image until I turned ON the cooling. Over the course of the evening I incrementally decreased the CCD temp without any negative effects. I was able to image several hours. By the time I quit I had the cooling down to -5C.

    Firmware - 20
    Driver - couldn't find that but I downloaded "SetupDLApi.exe" on 18 Feb 2020
    Software - MaximDL 6.21
    Serial # - AL3200M-20020501
     
  5. Tom Haugh

    Tom Haugh Cyanogen Customer

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    I noticed that the cooling never goes below 13% even if the cooling temp is set above the current CCD temp. It is at 13% when cooling is turned on and never goes below after warm-up. Is that expected behavior?
     
  6. Doug

    Doug Staff Member

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    The cooling system has a minimum power level and can't go all the way to zero; 13% is the minimum. (Most cameras on the market work the same way, but lie about being completely "off". The engineer who developed the firmware for Aluma decided to report the actual power level.)

    We've bounced this around and we're all scratching our heads. If you could upload a couple of your oddball images (FITS format please) we'd be very interested to have a look.

    It might have to come back for an investigation. Let's see your images first.
     
  7. Tom Haugh

    Tom Haugh Cyanogen Customer

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    There are quite a few, how to you want them transferred? Can I use Maxim to bin them down?
     
  8. Doug

    Doug Staff Member

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    The images must be unmodified.

    You could use FileZilla (free download) to upload them to our ftp site, ftp.diffractionlimited.com

    Or you could use dropbox or similar.
     
  9. Tom Haugh

    Tom Haugh Cyanogen Customer

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    Can they be zipped without losing info?
     
  10. Colin Haig

    Colin Haig Staff Member

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    Yes, Zipping is lossless compression.
     
  11. Tom Haugh

    Tom Haugh Cyanogen Customer

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    Files on the way.
     
  12. Tom Haugh

    Tom Haugh Cyanogen Customer

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    I think I have found a pattern during testing on the evening of the 27th. I powered up the AL3200 without cooling on and took an image - all zeros. I then took an image 15 minutes later - all zeros. Fifteen minutes after that showed an image. I then took a couple to verify and again had images. I then turned on cooling set to 5°C. The next image all zeros. 5 minute delay - good image. I continued the pattern; a decrement in temp led to all zeros. 5 minutes or so later an image. I went down all the way to my standard -10°C and and after the 5 minute wait and the images resumed they were good for the rest of the evening.
     
  13. Colin Haig

    Colin Haig Staff Member

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    This is ringing a bell about an image being 1 behind.
     
  14. Colin Haig

    Colin Haig Staff Member

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    Got the images.
     
  15. Colin Haig

    Colin Haig Staff Member

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    Here's a first step to help resolve this.

    The power supply input voltage to the camera seems a bit low; it is 11.59V in many images. It's not so low that we know the power supply has failed, but it could be a bit better.

    The FITS header value is "INPUTV".
    This might be a connector isn't making good contact in either the power pack to DC extension cord or DC extension cord into the camera.

    With the power supply unplugged from the wall, can you check that there are no damaged or bent pins ?
    Specifically no bent pins in:
    Male connector on the DC power supply low voltage cable that goes into the extension cable
    Male connector on the DC extension cable that plugs into the camera

    Can you double check the DC cord is plugged firmly (but gently) into the extension, and the extension into the camera?

    Low voltage can happen when the cooler is running, as it draws a fair bit of current.

    After we check/eliminate this as a possibility, then we'll see what else is going on.
     
  16. Colin Haig

    Colin Haig Staff Member

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    Also, what is your "CV" filter?
     
  17. Colin Haig

    Colin Haig Staff Member

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    My colleague @Adam Robichaud is wrapping up work on some software updates that we will want to get you to see if it clears up the off-by-one effect.
    It will be a few days before it will be ready.
     
  18. Tom Haugh

    Tom Haugh Cyanogen Customer

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    No bent pins on the plugs nor evidence of bent pins on the receptacles. All connections were secure.
     
  19. Tom Haugh

    Tom Haugh Cyanogen Customer

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    From the AAVSO site: "CV: Clear (unfiltered), V-band comp star magnitudes (this is more common than CR)". I use some of the groups analysis software so I standardized the use of their codes for all my images.
     
  20. Colin Haig

    Colin Haig Staff Member

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    Ok thanks.
    Can you take a couple images with the cooler off, and let me know what the INPUTV value is?
     

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