Fan is running continously after Replacement

Hey,
as many others, my fan started to make strange noises. So I was looking for 3 pin 40x40 5V fan - wasn’t quite easy.
I ordered this one

https://noctua.at/de/products/fan/nf-a4x10-5v.

Of course the plug did not fit so I used the old one by splicing the wires.
Anyhow both the old and the new fan had 3 pins, yellow, red and black.

The new fan starts running as soon as I power up the PI but if I am right the fan control started to run the fan quite a bit later after a complete boot of the system.
The fan also seems to run at one speed only. So the fan control seems not to work.

Would it help to swap the red and yellow wires.
By googling the pin out I found out that there is no common standard for the VDC+ and the tachometric signal.

Is there some documentation about the pins of the fan plug at all?

THX

you might have a view

No. The original fan had 3 pins so I bought a 3 pin fan.
I the meantime support of the nf-a4x10-5v replied, stating that the fan is wired according to AMD/ Intel Standard. whatever this means. I have to check the standard.

usually a 3 pin wiring is not PWM, it is RPM
the SATA HAT 3 pin makes an exception with its PWM in the middle
you bougth a standard 3 pin NON PWM fan
for that fan is a 4 pin PWM version avail as well
for wiring of 4 pin fan to 3 pin HAT plug see link provided before

A nice white paper by noctua shows the standard and their wiring.

1 Like

can’t find the link, Could you please provide it?
Thy!

basically I was referring to my link in posting number 2

Disclaimer:
The modifications in this article are based on my experiences and if you find them useful to use you do so at your own risk.

to summarize
if your fan will be 4 pin PWM Noctua then you should connect
black to 3 pin plug black
yellow to 3 pin plug red
blue to 3 pin plug yellow (the middle wire)
green leave allone

Ok I hooked it up. Fan seems to be speed controlled now even though if I call the shutdown procedure the fan starts to turn at 100%. Also at startup. As soon the rock pi gets powered the fan goes on. After booting it slows down.
The original fan was off before start up and after shutting down.

Running at 100% is normal, since you have stopped the PWM and the signal will probably be left as a 1.
If you set the pin to 0 when you exist, the fan will stop.

Ok thx. Sorry but I am completely new to this. Where can I set the pin to 0?

Actually the code in main.py, in “def main” has a reference to turn off the fan, if it thinks you have a top_board. I retract my statement.

So if you use the “systemctl” command to stop you SATA service the fan should turn off. If you are just doing a “python3 main on” then the fan will probably stay on, if you ^C your way out of the code.

Retract that too, at least on a penta HAT. Doing a systemctl stop rockpi-penta.service" leaves you with a fan that then comes on full again. I would have to play with my Quad hat to see its behavior.

My penta-hat service did not like an explicit change using misc.py:set_mode to 0, the fan never came back when running the code, needed a reboot to reset the mode so that it would PWM again.

However, on it, and I think on the quad hat, putting: " fan.change_dc(0)" at the end of oled.py:goodbye did do the trick and retained the ability to start the service and have the fan run again.