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Old 01-10-2015, 09:38 AM
elken2004 (Australia)
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ZWO asi 174mc TEC modifications

Hi just thought I would share info on adding TEC cooling to the ASI174mc CCD.

I added a Melcore TEC I bought about 20 years ago.
It is a 12volt 127 couples TEC
I added thermal paste to both sides of the TEC and used a Northbridge heatsink from a PC mother board, it had two mounting holes that matched perfectly the diagonal 39mm holes on the CCD.
Then I screwed a ball bearing type CPU (older style) fan to the heatsink fins
I dob of epoxy the screws to keep the fan in place, then added tape to ensure airflow was pulled thru the heatsink to maximize on cooling.
The fan pulls air from the heatsink and expels it out the rear.
My tests on the bench, were first at 5 volts approx 1 amp draw. This reduced the operating temp of chip from 37 degrees down to about 15 degrees.
I then increased the voltage to 12 volts which drew about 3 amps, this reduced the temp down to about 12 degrees.
However the potential fan vibration might cause a negative effect on imaging.
I found the optimal was about 8 volts with 2 amps drawn.
This also was the best as far as condensation and fan vibration.

Oh PS the ambient temp was approx 22 degrees during these tests

The heatsink performed perfectly not at all warm, however the gain of cooling at 1o volts might be good, condensation not with standing of course.
A reduced fan speed at this 10 volt level would be good, I will have to modify the feed circuit to do this, as at the moment the fan is connected using a 6 ohm resistor, (very basic).
I will test using Zener to reduce its voltage from a common 12 volt source, minimizing the connections to CCD, I think a voltage of 6 or so volts will give enough heatsink cooling with nil vibration.

Each pair of photos show the temp graph and resultant 30 secs image with black cap on CCD.

The test software was FireCapture

all of this is to see how it performs for deep sky objects.
It will also certainly improve planetary photos too, plus plus gain

The weight increase in not significant either still quite a light package overall and good for grab and go imaging.

to be continued..........
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Click for full-size image (cooled 13.2.jpg)
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  #2  
Old 01-10-2015, 09:45 AM
elken2004 (Australia)
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I forgot to show pics of CCD mods

These pics are at full 12 volts as you can see condensation was high, when driven at lower voltage it was minimal.
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Old 01-10-2015, 10:53 AM
glend (Glen)
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You can reduce or eliminate fan vibration by sitting the fan on silicon pads on the heat sink. There are some very efficient heat pipe type PC graphic card or cpu coolers that fit TEC dimensions really well and are light weight.

I run a cold finger cooled DSLR and easily achieve -25C below ambient temp.. however, optimal is -5C to eliminate any sensor signal noise. A simple temperature controller will allow you set point temperature hold without having to fiddle with voltage control yourself.

Good to see people adapting the ZWO cameras.
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Old 01-10-2015, 11:16 AM
elken2004 (Australia)
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mods

I would love to pull unit apart and do a cold finger, but considering how much they cost, nup.

I will see how time goes with this because i can do both TEC on and off.

as far as temp regulation, again keeping it simple

Cold finger I will do to my 1000d, as I have done a full spectrum mod to it.

i also just got a EOS1d markiii for very very little money as it was faulty, two hours later fully functional. was mighty chuffed.

I am also considering offering a service to do all these kinds of mods, as i have full workshop and tools to do this kind of work.
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Old 01-10-2015, 12:46 PM
glend (Glen)
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To stop the dew, stick the camera in a ziplock bag with a cutout for the lense and the TEC. Put some dessicant; n the bag or fill it with a gas like Argon. I use this on my DSLR and it works great.
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