Jump to content
Ultimaker Community of 3D Printing Experts
WTFockewulf

Fans not working after shorting fan leads *solved*

Recommended Posts

Hi Guys,

I have a very annoying Problem with my UM2. Due to a faulty duct (it broke during an overnight print) one fan came loose and the cable got smoldered thus causing a short circuit. After this, the (new) fans would only run on 100%. between 01 and 99% they would only "quiver". I replaced the 817 Transistor and when I measure the Voltage you can see it go up nicely to 24V as I increase the steps in the menu. But again, the fans only start up at 100%...

Any Ideas are much appreciated...

Rgds,

Philipp

Edited by Guest

Share this post


Link to post
Share on other sites

Wow the problem persist after changing the 817.. I'm clueless. Can you plug the led on the fans to see how the respond? Maybe is the actual fans the ones that died?

The leds use the same v so if they work the same way the cheapest solution could be to change the led to the fan making a custom firmware and changing the pin.h assign table.

Share this post


Link to post
Share on other sites

Oh I see you replaced also the fans? Umm try the led on the fans to see if the pwm works. Maybe the fns you got ain't PWM-able? Are they from UM resellers?

 

OK, I wired up the LED to the PWM and it works perfectly. I can regulate the brightness of the LEDs with the FAN control. Fans wont work on the LED control though...

Is it possible that the little controller in both fans could be shot? The other fans are not original UM. Best guess is these are not PWM fans... Would make sense. Seeing the cables of one of mine are cooked, where can I get replacement fans?

Share this post


Link to post
Share on other sites

Any UM reseller have them. I think they are 10-13€ each? I bought a couple a few months ago.

Nice at least the board is ok now that you fixed it.

 

Neotko,

yes, very glad the board is fixed. I will order the fans tomorrow. Hope they arrive quickly, I have customers waiting :p

Rgds and thanks for the help, its much appreciated!

Philipp

Share this post


Link to post
Share on other sites

Best guess is these are not PWM fans...

 

Technically speaking, none of the fans in the UM2 are PWM fans; that would require a third lead for a triggering signal. The UM2 runs ordinary DC fans as PWM fans by chopping the power input. Not all fans react equally well to this, and the PWM frequency may be the issue here.

Share this post


Link to post
Share on other sites

 

Best guess is these are not PWM fans...

 

Technically speaking, none of the fans in the UM2 are PWM fans; that would require a third lead for a triggering signal. The UM2 runs ordinary DC fans as PWM fans by chopping the power input. Not all fans react equally well to this, and the PWM frequency may be the issue here.

 

It would be interesting to actually know what specs an user must search for, to have fans that work on um2 boards.

Share this post


Link to post
Share on other sites

Agreed, there's an annoying lack of specs regarding fans (airflow/pressure/etc).

I've been wondering awhile whether or not there's anything to be gained by replacing the side fans with thicker ones for greater pressure. I have this sneaky suspicion that angling the airflow as aggressively as it is done on the UM2+ head assembly might severely limit the airflow due to lack of static pressure.. the fans are awfully thin after all so I can't imagine they produce much. Then again I'm not that sort of engineer, and airflow is a surprising thing sometimes so I can't say for sure. I'd like to try to replace them with something else, but it gets somewhat random when you don't have any specs to compare with.

Regarding the PWM issue, it would be a quick modification to replace the fans with proper PWM controlled ones, as long as we have access to the PWM output and a suitable power bus. But again, with no fan specs, it would be random experimentation.

Share this post


Link to post
Share on other sites

Agreed, there's an annoying lack of specs regarding fans (airflow/pressure/etc).

I've been wondering awhile whether or not there's anything to be gained by replacing the side fans with thicker ones for greater pressure. I have this sneaky suspicion that angling the airflow as aggressively as it is done on the UM2+ head assembly might severely limit the airflow due to lack of static pressure.. the fans are awfully thin after all so I can't imagine they produce much. Then again I'm not that sort of engineer, and airflow is a surprising thing sometimes so I can't say for sure. I'd like to try to replace them with something else, but it gets somewhat random when you don't have any specs to compare with.

Regarding the PWM issue, it would be a quick modification to replace the fans with proper PWM controlled ones, as long as we have access to the PWM output and a suitable power bus. But again, with no fan specs, it would be random experimentation.

 

A bit offtopic, but, since you mentioned it. I think the best alternative atm is @Gudo fan system

https://www.youmagine.com/designs/35x35-12vdc-um2-family-centrifugal-fan-shroud

Curiously @Gudo uses the 24V of the same fans UM did use on the UM3 (UM uses the same model but 5V version on um3). Also his design is much more centered airflow-wise. So the air should be pretty nice.

Share this post


Link to post
Share on other sites

Right, FWIW, my UM2 is working again.

After changing the 817 I first bought a set of Sunon Maglev MC30101V2-0000-A99 Fans. They do not work with the board. I then bought some cheap fans from here:

Click me softly and they do the trick although they have the same specs as the more expensive Sunon ones... go figure.

Both are brushless, both are 12V...

Share this post


Link to post
Share on other sites

After changing the 817 I first bought a set of Sunon Maglev MC30101V2-0000-A99 Fans. They do not work with the board. I then bought some cheap fans from here:

Click me softly and they do the trick although they have the same specs as the more expensive Sunon ones... go figure.

Both are brushless, both are 12V...

 

The problem here is that these are DC fans and as such, have their own internal circuits for switching the stator windings on and off in order to make the rotor spin. What we're doing when we try run them of a pulse width modulated fan bus, is turn the entire fan (and thereby the switching circuits) on and off at an alarming rate. It won't necessarily work on all fans, and is often dependent on the PWM frequency.

A DC fan designed for PWM operation is supposed to be powered on all the time, and instead takes the PWM signal on a third wire - and the fan electronics never lose power.

So yeah, it's hit and miss with this sort of thing. Most normal DC fans can be run with a PWM signal just fine, provided the PWM frequency is low enough. Ideally though, you would want to move the frequency somewhere above 20KHz since a great many fans will appear to become much louder when switched with a frequency inside the range of human hearing. Unfortunately not all fans react equally well to this.

Share this post


Link to post
Share on other sites

Thanks for the Input. These are ball raced according to the product description.

Truth be told, I am quite suprised These DC brushless fans work with PWM at all. The little controller must initialize first, check the position of the bell and then power up... and all this pulsed many times per second. I work a lot with brushless motors in my rc hobby and thats a lot of work for the ESC to do. Thats probably also the reason why the UM Board has a short 100% pulse when turning the fans on. Its easier for the ESC to determine the RPM of a moving bell.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!