24v 2 wire PWM fan

General Discussion
1

Basic Information:

Printer Model: Voron 2.4
MCU / Printerboard: Octopus v1.1
Host / SBC: mainsail
klippy.log
klippy (6).log (853.8 KB)

Fill out above information and in all cases attach your klippy.log file (use zip to compress it, if too big). Pasting your printer.cfg is not needed
Be sure to check our “Knowledge Base” Category first. Most relevant items, e.g. error messages, are covered there

Describe your issue:

…I recently purchased a 5015 24v 2 wire Berserker fan for my stealthburner. The seller listed it as PWM.

When I installed it and tried to turn it on, nothing happens. I took it out and tested it on my benchtop power supply and it worked fine.

Do I need to change something in my config to get it to turn on?

Thanks in advance!

2

Just a little background on fan control and the terminology because a fan being listed as “PWM” is a little misleading:

“PWM Fans” are an actual specific thing vs a fan being controlled by PWM via it’s power.

All 2 wire fans are capable of rudimentary speed control via PWM.
In that scenario (with 2 wire fans specifically that is), all that it does is connect and disconnect the fan from the ground at a variable frequency.

With the effect of the fan seeing a roughly “average” power of the ratio of the on time and off time.

The circuit looks like this.
image

I say rudimentary because there is no actual “control” mechanism, it’s literally just turning the fan off and on really fast at different rates to make it look like variable power and thus speed control.

I say this because there are actually TRUE PWM fans with 3 and/or 4 wires (4 wires if there is a tachometer signal as well). These actually have built in circuitry to take a PWM input and it will match the fan speed to the duty cycle (ratio of on vs. off).

This actually HAS a control mechanism (the circuitry in the fan) and thus is more reliable and accurate. But of course they’re more expensive.

image

But to your question.
I’m assuming NHK is an LDO Nighthawk.
If that’s the case then your config file looks fine and the fan should work.

[fan]
pin = nhk:gpio6
max_power = 1.0
kick_start_time = 0.1
off_below = 0.1

You should be connecting it to the part cooling fan in the top right. WIth the power to the right most + pin and the ground to the left most - pin.

image
image596×528 76 KB

3

Thanks for that awesome explanation!

So, I tried it again and still nothing. But when I removed the front of the SB, the entire piece was warm. I touch the fan and it was hot. I then made sure it wasn’t bound up and it would spin freely by hand.

I took it to my bench top power supply and the fan started right up.

I put the fan back in and reversed the polarity and still nothing.

Now I’m at a complete loss. I think I’m going to put my original fan back in so I can get some printing done and then give it another try later on.

4

Did you spin it through several revolutions by hand? Sometimes they get bound up slightly at certain parts and that’s enough to stall it.

Also, Are you SURE it’s a 24V fan?
I’d check the front of the label to be sure.

You said you tested it on the benchtop power supply so that SHOULD prove it’s 24v but weirder things have happened.

If it’s getting hot it usually means…

A.) It’s stalled
or
B.) It’s running at the wrong voltage (too high)

5

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.