Astrovid Stellacam EX

CPU Fan Modification!!!

Created:       09-21-2002.
Last revised: 09-25-2002.

While the Stellacam Ex is a great video camera, it has one little drawback, "warm pixels".

This is the 'false star' effect you get when the ambient outdoor air temperature is warm (>70 F), the camera begins to heat up internally, and the deep-sky settings are at maximum. They show up as bright stationary 'stars' while in deep-sky mode, (sense-up to x128, manual gain 18db), and are present because the CCD chip in the camera is not cooled.
After reading several articles on using CPU fans to air cool webcams & digital cameras, I decided to try and reduce the 'warm pixel' problem on my Stellacam. I picked up several small 'mini' CPU fans at a local Hamfest/computer show. (invested $5.00). There are basically two types, a standard low speed (thin) fan, and a high speed model (thick). After hooking up a battery and trying each one, I decided to go with the high speed model, as it had a much greater air flow.
Opening the camera: Remove the four (4) small phillips flat head screws. The top cover (which covers 3 sides) has a snug fit, but will come off with little trouble. On the inside there is one main circuit board that goes the length of the camera. There is a small circuit board perpendicular to the main board that holds the CCD chip. At the rear is the connector that supports the power and video connectors. Gently loosen the 'Auto Iris' from the bottom cover and remove the cover. Be careful of the little white flat wire strip that plugs into the front circuit board. You can accidentally knock it out of the socket. If you do, then just gently plug it back in.
Making the Mod: The first step is to drill several small exit air holes in the bottom cover.
Next step is to outline the size of the fan on the top cover. I chose to mount the fan on the side, but the top may be a better location. (When the camera is mounted on my SCT, the fan very narrowly misses hitting the autofocus motor)
Now comes the step that's not for the weak of heart. (cutting the cover). Actually, before I did this, I first tried out the fan by popping out the 'auto iris', and mounting the fan over the small hole. There was a noticeable decrease in 'warm pixels', so I decided to cut a much large hole that would allow maximum air flow from the fan.
(unfortunately, I have a well earned reputation for not being able to cut straight :) Step #4 (after you recover from cutting the cover), reassemble the camera.
From an article on digital cameras in the October 'Sky & Tel", I went with mounting the fan by using velcro. So the next step is to apply stick on velcro around the new opening on the side of the camera. (this helps to hide my less than perfect cut job).
Apply velcro to the corners of the CPU fan. Try not to cover up too much of the fan's air flow. Then position the fan over the new cover hole and press the velcro together. I also applied black electrical tape around the fan sides to direct the air flow into the camera and not out the side gaps around the fan. It also helps to keep out dust.
I wired a 9-volt battery connector to the fan so that I can power it. As this was a little underpowered, I made a power adapter from another 9-volt connector that snaps onto the first connector, (keeping the 9-volt battery option), but allows me to plug the fan into either AC wall wart, or a 12-volt DC battery. You should be able to find everything you need at a Radio Shack.
That wraps up the Stellacam Ex CPU Fan Modification.
My next project is to figure a way to get chilled air to the CPU fan. (maybe dry ice in a small cooler with an air hose drawing air from the bottom of the cooler and attaching to the CPU fan?)

Preliminary test results look good, But.......

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