Resolved Loss of images after cooling turned on.

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

 

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

 

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?

 

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

 

Can they be zipped without losing info?

 

Files on the way.

 

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.

 

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

 

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.