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ZWO Camera Fan Buzzing: Old and New fan buzz

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#1 dwyer2bp

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Posted 18 May 2022 - 06:38 PM

Greetings CN,

 

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.

https://drive.google...iew?usp=sharing

 

Thanks!

 

Newer 0.43Watt ZWO Fan models (with the buzzing):

med_gallery_308122_12783_533886.jpg

 

 

Fan model in the 294MC Pro I have (0.8Watt):

med_gallery_308122_12783_496183.jpg


Edited by dwyer2bp, 18 May 2022 - 08:07 PM.


#2 John Miele

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Posted 18 May 2022 - 06:45 PM

FWIW, my ASI1600MM pro fan sounds exactly the same...



#3 LuscombeFlyer

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Posted 18 May 2022 - 07:18 PM

My ASI294MC-Pro purchased in March of this year is completely silent.



#4 dwyer2bp

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Posted 18 May 2022 - 08:09 PM

My ASI294MC-Pro purchased in March of this year is completely silent.

I've edited my photos to indicate that it's not an "old vs new" fan model that buzzes. Some fans buzz and some fans do not. If you ever take the back off your camera to peak at the fan model and power rating I'd like to know which model it is in you 294MC Pro. It doesn't hurt anything to remove the back but I wouldn't ask you to do it if you don't want to.



#5 michael68

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Posted 18 May 2022 - 08:22 PM

I have an ASI294MC and an ASI1600MM. Sometimes I have to put my ear to them just to make sure the fans are working.

Completely silent. I'll pull the back off mine and see what I can find.


Edited by michael68, 18 May 2022 - 08:28 PM.


#6 michael68

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Posted 18 May 2022 - 08:37 PM

Here ya go. My ASI294MC later model.

 

IMG_1703.jpg


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#7 xiando

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Posted 18 May 2022 - 08:46 PM

I wasn't able to get your mp4 to play. Having said that, unless it's the normal whirring "buzzing of a fan under axial rotation" (effectively a gyroscopic resistance, or torque, that results in excess noise from perpendicular stresses on the axle, which IS a distinct possibility for these little fans under duress), my guess would be either bad bearings (unlikely with a new motor) or an obstruction. 

 

The fan on my camera makes a little noise, but I've never subjected it to high enough acceleration to produce axial stress...(again, I can't hear yours. the interface - under Chrome - doesn't fire up the MP4 for me)


Edited by xiando, 18 May 2022 - 08:48 PM.


#8 dwyer2bp

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Posted 18 May 2022 - 08:58 PM

I wasn't able to get your mp4 to play. Having said that, unless it's the normal whirring "buzzing of a fan under axial rotation" (effectively a gyroscopic resistance, or torque, that results in excess noise from perpendicular stresses on the axle, which IS a distinct possibility for these little fans under duress), my guess would be either bad bearings (unlikely with a new motor) or an obstruction. 

 

The fan on my camera makes a little noise, but I've never subjected it to high enough acceleration to produce axial stress...(again, I can't hear yours. the interface - under Chrome - doesn't fire up the MP4 for me)

I can hold my fan still at a certain angle and hear a continuous noise. There is the constant whirr noise that is very normal and seems higher pitch than the suspect noise I am referring to. My best description of this noise is that it sounds like the moving part is brushing against a non-moving part. The fact that I can reproduce it with motion makes me think that I am introducing just enough force to cause an imbalance that may lead to some parts touching that should not be.

 

 

Here ya go. My ASI294MC later model.

 

attachicon.gifIMG_1703.jpg

I have two of these and they both make the noise that yours does not. So maybe it's just some fans are not made as well as others.

 

I might try and source some better alternatives.



#9 dwyer2bp

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Posted 18 May 2022 - 09:01 PM

I wasn't able to get your mp4 to play. Having said that, unless it's the normal whirring "buzzing of a fan under axial rotation" (effectively a gyroscopic resistance, or torque, that results in excess noise from perpendicular stresses on the axle, which IS a distinct possibility for these little fans under duress), my guess would be either bad bearings (unlikely with a new motor) or an obstruction. 

 

The fan on my camera makes a little noise, but I've never subjected it to high enough acceleration to produce axial stress...(again, I can't hear yours. the interface - under Chrome - doesn't fire up the MP4 for me)

You might also try downloading the file and using your favorite video player.



#10 unimatrix0

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Posted 18 May 2022 - 09:13 PM

 

 

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.

 

 

 

 

 

Fans possibly changed for efficiency or so it consumes less power.  They did tests and ended up with the 0.43W that is still efficient enough to do its role. They were probably thinking about the growing number  ASIAIR owners who power them through that tiny raspberry Pi with limited power output. 
The problem would come if you notice that it's unable to keep a constant temperature, but if it does, then I don't think there is anything to worry about. 

My first QHY camera sounded like it was ready to take off like a helicopter, until I adjusted the wires.  BTW, these should be easy to replace or even upgrade. If you can't find the same model, I advise to look on eBay for laser printer fans, for which Sunon supplies 1000 different types of fans.  



#11 Oort Cloud

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Posted 19 May 2022 - 09:43 AM

I can hear my fan, but I wouldn't describe the sound as problematic in any way, and it's capable of imaging stars as pinpoints if my guiding is good for the entire exposure, so it's not causing any problems with my images either.

I did see a thread on here the other day though, where folks were talking about replacing the fans and supports - I believe it was in the experienced imaging forum.

#12 TelescopeGreg

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Posted 19 May 2022 - 01:35 PM

I believe that's just the sound made by the blades as they spin by the fan's supports.  Totally normal.  You might check to be sure the wires aren't getting close to the spinning blades, as even if they don't touch they can cause a lot of noise just from the beating air flow.

 

If separately you can feel a vibration, that's bad.  I'd replace the fan in that case.



#13 dwyer2bp

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Posted 19 May 2022 - 03:17 PM

I believe that's just the sound made by the blades as they spin by the fan's supports.  Totally normal.  You might check to be sure the wires aren't getting close to the spinning blades, as even if they don't touch they can cause a lot of noise just from the beating air flow.

 

If separately you can feel a vibration, that's bad.  I'd replace the fan in that case.

It's defninately not the wires but you may be right about the support 'veins'. There are 3 slightly curved veins supporting the fan, kind of like the secondary mirror in a newtonian. The blades seem to already be very close to these veins so maybe a slight imbalance is causing some clipping.


Edited by dwyer2bp, 19 May 2022 - 03:18 PM.


#14 RogerM

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Posted 19 May 2022 - 03:40 PM

There could be residual 'flashing' from the injection moulding process, look for interference between the motor and fan blade hubs.  Injection molded parts are also prone to warpage, especially from high volume processes. That coupled with slop in the bushings could account for the 'ticking' sound as you rotate the camera body.  See if there's sufficient space between the fan and motor hubs (you might be able to increase the gap by hand)


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#15 dwyer2bp

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Posted 26 May 2022 - 01:20 AM

I ended up using a different fan: Noctua NF-A4x10 FLX

https://www.amazon.com/dp/B009NQLT0M

 

I had to modify the cable and crimp my own connector for it to mate with the zwo camera (luckily I have all the tools/parts to do this). The screw mounting holes on this fan are larger than the zwo OEM fan but this fan comes with vibration-control mounting pieces that seem to work just fine. I would probably not recommend this fan due to the work involved in using it, but so far I'm really happy (no more suspicious buzzing and it cools the same).

 

I received some feedback from ZWO (via AgenaAstro) and they basically said the noise is normal. I tend to disagree. It is a very expensive camera and they should have better standards for their fans.

 

I'll probably use the other two ZWO buzzy fans to cool my raspberry PI

 

Clear Skies!


Edited by dwyer2bp, 26 May 2022 - 01:24 AM.


#16 DirtyRod

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Posted 26 May 2022 - 01:28 AM

I have an ASI294MC and an ASI1600MM. Sometimes I have to put my ear to them just to make sure the fans are working.

Completely silent. 

Same for my 533MC Pro I bought last year and the 294MC Pro that arrived today.



#17 dswtan

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Posted 26 May 2022 - 01:46 AM

As the old saying goes - if it hurts when you do *that*, stop doing *that*!

 

Moving the camera around like that is not standard operating procedure…
 

I can hear my fans and I’m glad to, to know they’re working. YMMV!



#18 dwyer2bp

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Posted 26 May 2022 - 07:04 AM

As the old saying goes - if it hurts when you do *that*, stop doing *that*!

 

Moving the camera around like that is not standard operating procedure…
 

I can hear my fans and I’m glad to, to know they’re working. YMMV!

 

I was simulating a slewing telescope mount. If I hold at some angles, the buzz was constant. I even got the fan to stop spinning when holding at an angle (once, but could not reproduce).



#19 BucketDave

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Posted 26 May 2022 - 03:45 PM

As a former aeronautical engineer, if the fans are buzzing, I'd agree that they are probably being excited into resonance by wakes from upstream components, or by flow separations on the blades (probably because the fan is seeing too much blockage downstream). You wouldn't CHOOSE to design it that way but you might accept it if it didn't affect the camera imaging.

I think you are right to try different fans, hoping to find one that suits this installation better.


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