Camera Fan Vibration

[Dasman56]

I thought i would post a new thread explaining some troubles i have had with fan vibration on my camera as it may be of some interest to others that run into similar issues.

I bought a second hand QHY163c and was using it on a Hyperstar + 9.25HD for a little while with what seemed like no issues. But when i switched to the Native F10 focal length i was getting streatched stars. Which i first thought might be collimation or back focus. Now a lot of advice was saying you need a OAG at F10 or else. But you don't get streatched stars with 1 sec exposures. Now i had come across some info on people having fan vibration issues with ZWO cameras, and sure enough as soon as i disconnected the 12v power on the QHY perfect sharp round stars.

So here is what i did. The first thing i tried was a new fan with no improvement. Removing the filter draw did make a noticable improvement, my imaging train without the draw is a solid billet macined assembly. Whilst a major effort was made to isolate the fan it did not completely solve my problem. I finally got nice round stars but they still looked slightly bloated.

Now without the more extreme distortion at the start i probably would not have questioned my stars. But they were still not as sharp as with the fan off. My fix was to add a 50ohm resistor to slow the fan, along with the isolating and my problem is solved. . I wonder how many people experience slight star bloating from fan vibration and don't even know?

[joshman]

I would say quite a few. it's a known phenomena that has been discussed at length over on the cloudynights forum. Though it mostly seemed to affect the ZWO camera. I've replaced my fans with the Fractal Designs R3 Silent fans, and they've been really good.

[Leo.G]

I have to agree with Josh on this point, fan quality is far from any standards, a high quality fan is worth it's weight in gold.
My fan experience is only playing with modified cameras (A lot of experience playing with computers and electronics cooling systems) where I've stripped the guts out and put them in a jiffy box/case, not professional astro cameras obviously. I have however found out along with high quality fans, good quality soft fan mount rubbers have had a huge impact on my designs where they can be fitted, not possible on everything I do know that.


Many people will tell you you need a fan with Japanese bearings, the common brands suggested on various forums do always seem to work well.
This is great if you can actually get in to replace the fan, not always possible without manufacturers intervention.
The resistor which is effectively reducing the voltage to the fan and reducing the fan speed which reduces the vibration, it doesn't affect the operation of the camera?

[Dasman56]

That is something i should have mentioned. I only replaced the fan with what i could buy locally. (Not PRC made but not Japan either) On the QHY the fan is hard mounted to the heatsink. So soft mounting it did stop the elongated stars, but that's when i realised although the stars seemed fixed they were still not as sharp as they were without the fan on.

I am going to order a Fractal Designs fan that Josh Mentioned. I had a search and they look good. I could still maintain -5c (thats what i use) without a fan at all. So hopefully in the hotter weather the fan can keep up with the resistor installed.

[Leo.G]

Ebay is your friend when searching for fans, what size is the fan?
RS components also sell decent fans, they used to have free delivery but now charge but some items are better buys than you'll find most places, sometimes not but I always check there.

Noctua branded fans always get very high regards for quality. There are cheaper in the range and price often reflects the quality.

https://gamersnexus.net/guides/779-computer-case-fan-bearing-differences

https://blog.louwii.com/2021/11/pc-case-fans-bearing-types-whats-the-best/

It often comes down to the bearing and blade designs and I find the noisier fans generally vibrate more, partial blade design, partial bearing design.

I recently purchased a new computer case for my son and built him a new system with used parts I found extremely cheap on the local plaza notice board. It just so happens to be a Fractal designs case (Define R5) with 4 fans (from memory, the case cost more than I'd usually spend on an entire build for my own purposes) and I can tell you the box is SILENT and not the smallest amount of vibration through it. I'm quite experienced with computer gear and my son has a server cabinet sitting in the middle of our kitchen with 16 high spec twin (and quad) Xeon processor blade servers populating the cabinet, when the thing starts up it sounds like a 747 taking off and the entire house vibrates. HP know how to design fans for the intended purpose, alloy blades like shaped jet turbines.

But it's nice to sit behind on a summers day when it starts up. As long as my toupee doesn't blow off.....

[floyd_2]

I had a problem with the fan on my ASI533MC-PRO late last year. Suddenly my star images made it look like the mount was ever so slightly circling the stars during an exposure. I was at a loss as to what could have been causing it at the time, until I wondered if the fan had a bad bearing. I put my hand on the camera and took a shot - it was perfect.

I ended up grabbing a Noctua NF-A4x10 FLX to replace the fan in my camera. It came with silicone mounts which I also used (instead of the stock screws). It's as good as silent and absolutely vibration free. The mounts keep the fan somewhat isolated from the frame of the camera which also helps.

For $30 I thought that it was money well spent.