High pitched whining noise from the 2 outer fans

Flagship K Series Creality Flagship K2 Plus & CFS
1

A few weeks after I got my K2 Plus combo it started making this high pitched whining noise. I was able to isolate the issue to the 2 outer fans. NOTE: The noise happens whether or not the fans are turning. Disconnecting those 2 fans makes the noise stop immediately.

Creality support has been great. So far, they sent me a replacement power supply and 2 new fans. Unfortunately, that didn’t fix it.

I’m attaching a video that demonstrates the issue. I’d love to hear if anyone else had this issue and how they fixed it.

Oh - the machine is plugged directly to a wall outlet with nothing else plugged into it. There are other devices on that same circuit, though - mainly lighting.

Here’s video of the issue: https://drive.google.com/file/d/1MLgSPu4hh5OlX3ZevPCYdg1MeA3LqI5q/view?usp=sharing

2

Does the coil whines goes away when power on? I know some dc fan will coil whine at lower power/pwm signal.

Is the fan still turn on and off correctly right?

3

yes, the fans work just fine, seemingly. The whine does NOT go away when they spin, though. It’s ever present unfortunately. It’s super loud and annoying.

I wonder if a quality power strip would make a difference? It’s plugged directly into the wall outlet. I’m not entirely sure what else is on that circuit.

4

BTW, I made a short video about replacing the filament break detector and you can hear the whine in the background…

5

Do you have somthing to mesure the voltage of the cables? Maybe there is something off with their standby power?
Preferably something fine tuned to mesure 24volts and below

if it where a car electronics i would say it sounds like a grounding issiue haha, but i did once hear a simmulare sound from a potention? meter (turns the voltage upp and down for speed controll) in that case i could only get a new one.

Have you followed the cables? is there a chance they have been damaged somehow from somthing?

6

Yeah, sound like voltage issue, may need new mainboard perhaps if you already replace the fan.

7

This is the response from Creality support:

Our senior technicians have reported that the issue may be caused by a faulty lower-level motherboard or a faulty chassis fan cable.

They’re sending me those parts. Hopefully that fixes it!

8

Mine brand new 1 week old K2 SE Combo is doing this exact same issue. My printer is upstairs in a bedroom. If I leave the bedroom door open its so loud I can hear it downstairs. It resonates throughout the house. Its impossible to not hear it. So much so that I only print when Im not home. I 1000% regret buying this printer. I should have went with a Bumbu Labs like my buddy told me too.

9

looking for a bit of follow-up, as mine sings as well.

did the parts fix the noise?

10

It sounds like there is still voltage on the fans. It’s the same sound I get when I use an RPM controller on certain fans and the voltage is too low for them to start spinning.

11

Hey, I just saw your post and wanted to chime in because I’ve been experiencing a very similar issue with the chamber exhaust fans, as well as the side fans inside the chamber on my K2 Plus.

In my case, instead of a high-pitched whine, the fans make a loud buzzing noise. I reached out to Creality, and they ended up sending me four replacement fans, but the issue still persists.

I’m not sure if you’ve already managed to solve your issue, but from what I’ve found so far, it seems like this may be related to the way Creality is controlling fan speed with 2-pin fans. Since these fans only have positive and negative wires, the fan itself is not processing a PWM signal like a 4-pin fan would. Instead, it appears that the MCU is switching the fan power on and off directly.

While looking through the printer config, I noticed that under temperature_fan chamber_fan, the cycle time is set to 0.010, which corresponds to about 100 Hz. That matches the frequency my fans seem to be producing. I tried increasing the frequency, but the printer started throwing error codes like XS3000 and XS3002. That makes me think either the hardware cannot handle the change, or Creality has locked this setting from being adjusted.

For anyone wondering, I also tested the fans using a bench power supply at a lower steady voltage, and the buzzing was not present. Because of that, one possible workaround may be adding a diode on the positive side of the fan connector and placing a capacitor after the diode, across the fan’s power leads. The idea is that the capacitor smooths out the pulsed voltage, which can reduce or eliminate the whining or buzzing. Basically, Creality is turning the fan power on and off rapidly instead of lowering the voltage to control speed.

The downside is that adding a smoothing capacitor may cause the fan to run faster than expected at lower percentage settings. The purpose of the diode is to keep the capacitor’s stored charge from feeding back into the board when the fan power switches off, so the stored energy only goes toward the fan.

Another possible workaround would be replacing the fans with something like Noctua NF-A8 fans and using Noctua’s NA-VC1, or another buck converter, to step the voltage down to a suitable level since those fans are 12V. The advantage of using the NA-VC1, at least to my understanding, is that it would give the fan a cleaner control method and allow it to run more quietly. However, going this route would likely reduce airflow and fan speed since Noctua fans are generally slower and lower-CFM. That may not be ideal if, like me, you’ve added HEPA filters or need to maintain stronger exhaust airflow.

This is just what I have discovered so far, and I still have not found a proper solution without trade-offs. Ideally, I would like to keep the airflow of the original fans while also keeping the lower speed control, but without the buzzing. Hopefully this helps someone else dealing with the same issue. If anyone has managed to solve this properly without losing airflow, low-speed control, or quiet operation, I would love to hear your feedback.

Here is a Snip it of what I hear: