I bought an ASI294MM Pro recently off CN that had a buzzing fan noise. It is somewhat constant depending on the angle you hold the camera, but it is its worst when the camera is moving around. Sounds like the fan has some considerable wobble causing some pieces to mechanically touch. So I decided to order a brand new replacement fan and it has the same precise noise 'issue'.
I figured maybe it could be the fan blade just barely brushing against the washers for the fan screws so I tried with the fan detached from the mounting holes but it has the same noise. So the noise comes from within the fan itself.
My ASI294MC Pro (from 2018?) does not have this noise at all. I compared the two fans and they seemed to have switched to a different model fan from the same manufacturer. The older fan model is a 0.8Watt while the newer one is a 0.43W. I believe I can even tell that less air is pushing through the newer model fan so I wonder why they made such a change. The replacement fan is sold as universal, so they expect you to put the 0.43Watt model in just any cooled camera that it fits in.
Anyway, does anyone notice this issue on their later model ASI cameras with the smaller cooling fans? (not the larger cooling fan models).
Here is a video demonstrating the noise of the brand new fan installed in the ASI294MM Pro. You may need headphones to really hear the buzzing, it is most noticeable when the camera is moving around.
Newer 0.43Watt ZWO Fan models (with the buzzing):
Fan model in the 294MC Pro I have (0.8Watt):
Edited by dwyer2bp, 18 May 2022 - 08:07 PM.