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Old 18-08-2014, 06:58 PM
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Paul Haese
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Join Date: Jan 2009
Location: Adelaide
Posts: 9,944
A small problem I had with my SBIG STXL

I thought it would be prudent to document this problem for anyone buying an SBIG STXL with integrated filter wheel and guide camera.

Over the last 6 months or so I had noticed images every now and then would present like the first image with odd looking artefacts. Allan Holmes from SBIG thought it might have been a clocking issue. The horizontal lines in this dark frame are not supposed to occur and I would see them in my darks and sometimes in lights. It had me worried that I had a lemon on my hands.

I brought this to the attention of SBIG and its representatives who were very responsive to the problem. After some testing it was requested to send the camera back to the States for assessment and repair. When the camera was tested at SBIG they could not find the problem and returned the camera.

Now something to note here. I only sent the camera head and not the filter wheel with integrated guide camera. It took about 4 weeks to be returned to me and I have had it back a few weeks now.

So a week or so ago I decided to test the camera again whilst waiting for an adapter to arrive. To my dismay I was once again getting the same problem with my darks. So I brought the camera home from the observatory and tried the camera again from home. I wanted to narrow down the causes of the problem and wanted to rule out anything at the observatory. With the artefacts appearing at home I knew that the cause was not in the dome via RF or power related possibilities.

So now I thought I would remove various cables until I found the route cause. There is a HDMI cable that connects the integrated guide camera to the main camera. It is quite thick and looks very robust. As it turned out the HDMI cable which supplied with the camera was the cause of the problem. To determine this I first took darks without the cable attached to both the camera and the guide camera. Darks were perfect. As soon as I attached the cable, the darks had artefacts again. Then I used a spare HDMI cable to determine if it was the HDMI cable or part of the main camera or the guide camera. In this instance it was the HDMI cable. The spare cable attached connected the guide camera and also did not create artefacts. The second image shows a typical dark since installing the new HDMI cable.

I don't know why the cable causes this problem, but if you see it on your STXL camera, this might be the cause. I would welcome any theories as to why the cable was causing this. Maybe the earth shield was faulty.
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