[Closed] Print fan wine noise at lower than full speed  

Re: Print fan wine noise at lower than full speed

did you end up replacing the fan? same issue here

Re: Print fan wine noise at lower than full speed

I have the same problem. I noticed it when printing flexible filament where fan speed is quite low.

Re: Print fan wine noise at lower than full speed

I have the same problem too.

Re: Print fan wine noise at lower than full speed

I have the same problem too.

I have the same problem. I noticed it when printing flexible filament where fan speed is quite low.

Prusa is replacing mine under warranty.

video

Re: Print fan wine noise at lower than full speed

Same noises coming out of my print fan at low speeds.

Can someone who receives a replacement confirm that it does not exhibit the same noise? I was operating under the assumption that it wasn't a defective fan, but rather the way its motor reacts to PWM. I use plenty of small motors in robotics applications that whine similarly when using PWM to slow their speed.

Re: Print fan wine noise at lower than full speed

It is caused by the specific PWM frequency that the microcontroller uses. Replacing the fan is unlikely to change anything, unless your fan also happens to have a different problem making it even worse than normal.

I put a request for the Prusa devs to consider switching to software PWM if possible, which fixes this problem on Marlin-based printers, but I don't know if it will be possible due to the limitations of the Einsy board.

https://github.com/prusa3d/Prusa-Firmware/issues/460

If many people give a thumbs up or reply to this issue on Github, it is more likely to get their attention.

Re: Print fan wine noise at lower than full speed

It is caused by the specific PWM frequency that the microcontroller uses. Replacing the fan is unlikely to change anything, unless your fan also happens to have a different problem making it even worse than normal.

good info, I wonder why it only affects a few of us?

that said, it would be nice if it was just a regular 12v blower fan, then at least we could swap in different (more powerful) fans. I couldn't find a single 5v pwm fan on amazon.

Can someone who receives a replacement confirm that it does not exhibit the same noise? I was operating under the assumption that it wasn't a defective fan, but rather the way its motor reacts to PWM. I use plenty of small motors in robotics applications that whine similarly when using PWM to slow their speed.

I'll report back when I get mine, hopefully this week. Are PWM controllers in PCs that different? I have dozens of pwm devices sitting next to me (pumps, fans, etc) and the motherboard controller and external pwm controller have never whined like this.

Re: Print fan wine noise at lower than full speed

Hello,

i have the same problem. I already contacted suppport and got a spare fan. I changed the fan but the wine noise is still there.
This is how it sounds:

I tested different capacitors connected between the power supply and ground of the fan. 10µF worked the best but the noise is still there espacially on low duty cycles.

You can turn the print fan on without print anything over Settings->Temperature->Fan Speed

Re: Print fan wine noise at lower than full speed

It is caused by the specific PWM frequency that the microcontroller uses. Replacing the fan is unlikely to change anything, unless your fan also happens to have a different problem making it even worse than normal.

good info, I wonder why it only affects a few of us?

The default PLA runs the fan at 0% and 100%, I expect this is why. Mine also whines when not at 100%

Re: Print fan wine noise at lower than full speed

Thank you everyone for your response.. Good to know, I'm not alone. In my opinion, this could be handled by software.. So hopefully within a new firmware, there will be some changes about PWM

Re: Print fan wine noise at lower than full speed

Same problem here. Noticed it today when I printed with PETG for the first time. It‘s really extreme, I had to stop the print...

An official statement would be nice!

Re: Print fan wine noise at lower than full speed

It is caused by the specific PWM frequency that the microcontroller uses. Replacing the fan is unlikely to change anything, unless your fan also happens to have a different problem making it even worse than normal.
Does anyone know what the timer usage is on the processor? If there's a dedicated timer generating the PWM (probably both fan PWMs), then simply setting the base frequency of the timer would solve things.

... just looked at the code:
// The fan interrupt is triggered at maximum 325Hz (may be a bit more due to component tollerances),
// and it takes 4.24 us to process (the interrupt invocation overhead not taken into account).
ISR(INT7_vect) {

... just couldn't find out where INT7 is coming from.

- Martin

Re: Print fan wine noise at lower than full speed

In temperature.cpp
#if defined(FAN_PIN) && (FAN_PIN > -1)
SET_OUTPUT(FAN_PIN);
#ifdef FAST_PWM_FAN
setPwmFrequency(FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
#endif
#ifdef FAN_SOFT_PWM
soft_pwm_fan = fanSpeedSoftPwm / 2;
#endif
#endif

FAST_PWM_FAN is there, but disabled in configuration.h:
// Increase the FAN pwm frequency. Removes the PWM noise but increases heating in the FET/Arduino
//#define FAST_PWM_FAN
This would shift PWM frequency up to 31 kHz (assuming F_CPU to be 16 MHz), which would definitely eliminate the whine. The question is if the fan is connected to a timer output pin.

- Martin

Re: Print fan wine noise at lower than full speed

Have got an replacement fan from Prusa, unfortunately still the same problem. The noise is really unbearable. 😥

Re: Print fan wine noise at lower than full speed

Have got an replacement fan from Prusa, unfortunately still the same problem. The noise is really unbearable. 😥

The noise is from the PWM control and exchaning the fan won't make a difference. The PWM frequency should be moved outside the audible range (up or down), which is a software task. There's an issue already:
https://github.com/prusa3d/Prusa-Firmware/issues/460
Vote there if you want it to get fixed. Currently they seem to be occupied by other tasks...

- Martin

Re: Print fan wine noise at lower than full speed

The noise is from the PWM control and exchaning the fan won't make a difference. The PWM frequency should be moved outside the audible range (up or down), which is a software task. There's an issue already:
https://github.com/prusa3d/Prusa-Firmware/issues/460
Vote there if you want it to get fixed. Currently they seem to be occupied by other tasks...

- Martin

The support told me (via chat) that the noise is not normal, he tested some printers and they don't show this noise. That was the reason for sending me a replacement fan...

Re: Print fan wine noise at lower than full speed

Just went searching to see if there was any solution to this as I agree with others, it's pretty unbearable anywhere less than 100%. Voted up the github issue, I guess no one has just built the firmware themselves with the option enabled? Might have to give that a go if I can find the time if not.

Re: Print fan wine noise at lower than full speed

The Golden Rule of PWM is never run it in the range of audio frequencies.... ie up to 20 KHz. I suspect Prusa never got the memo. The PWM typically is run up around 40 KHz. I don't know how they set the frequency. I always did it in software, so it is a doable fix for Prusa to fix this if they did it in the code or microcontroller initialization. Unfortunately changing the oscillator speed can throw a lot of other stuff out too.

Re: Print fan wine noise at lower than full speed

Same problem here as well. Reported the issue to Prusa and got a new fan, but still the same noise. I have to run the fan at full speed to be able to sit next to the printer. Not good for my ears (and I work as a sound designer).
Other than that I am very pleased with the printer so I hope they fix it.