How to start up the 24V fan.

[gdachs]

Mine has always had a behaviour where 0..254 = FAN OFF, and value 255 = FAN 100% ON!

All the fans are 24V fans, but geeetech forgot to set the jumper JP2 on the board near the fan connectors. Without the jumper all fans get only 12V. Full 12V lets the part cooling fan just spin, but pulse modulated with less than 100% is too less to let it run.
Just set the jumper and you should be able to get much better control. If you don't believe check the schematics for the board on github as I did.

[_kaktus_]

Mine has always had a behaviour where 0..254 = FAN OFF, and value 255 = FAN 100% ON!

All the fans are 24V fans, but geeetech forgot to set the jumper JP2 on the board near the fan connectors. Without the jumper all fans get only 12V. Full 12V lets the part cooling fan just spin, but pulse modulated with less than 100% is too less to let it run.
Just set the jumper and you should be able to get much better control. If you don't believe check the schematics for the board on github as I did.

I do not advise anyone to follow this advice.
Colleague gdachs gives advice, the consequences of which he does not know.

The best thing to do now is to explain why.

[gdachs]

Colleague gdachs gives advice, the consequences of which he does not know.

What makes you think that I don't know the consequences? That is just a lie.

Look into the comments to this youtube video where geeetech recommends to do what I told there and here.

[_kaktus_]

Hi


You wrote that you were browsing the diagram, so I think you know what you are saying ...
The problem is that you don't really know. That's my opinion and you don't have to agree with it.

See:

Zasilanie_GT2560revA+.png (31.63 KiB) Viewed 24453 times

This is a cutout with a power section from the GT2560 Rev A+ controller board. The board in version B has the same part.

Please interpret exactly what JP2 jumper does when the cap is put on it.

Writing that someone wrote something somewhere does not make sense here.
This is not an argument.

I could tell you to follow your advice and do a test. Unfortunately, I will not do that.

What do you think, why?

If you don't know, ask and I'll explain it in detail.

[gdachs]

What do you think, why?

If you don't know, ask and I'll explain it in detail.

Opposite to you I don't claim to know what you are thinking. I try to guess. The jumper bypasses the 12V regulator, so the 12V output of the regulator gets pulled up to 24V. That makes it hard for this regulator to do its job. This guy here demonstrates that the 12V regulator survives this procedure. In my opinion the regulator survives it because there is no current flowing through it if the jumper is set.

[_kaktus_]

Exactly.

The output of the positive voltage regulator is connected to a different voltage.

Making the experiences you are telling us about is, in my opinion, breakneck. This is a crashtest.
It's the same if someone said: jump out of the window on the first floor - nothing will happen to you because it's low.

This is playing with fate.
Certain things are simply not done.

In someone's case, such an electronic system can work. And for someone else he doesn't have to. Such a combination can cause more than just damage to the stabilizer.

If I had to advise you something:

• unsolder the chip first,
• then you can safely put the cap on the JP2 jumper.

I recommend this solution.
Then the circuit will always work reliably.

For me this is a design error.
In the next version of the controller board it is eliminated.

[gdachs]

Exactly.

Now that I have shown, that I am aware of the consequences I would expect an excuse.

But forget it, I have no need for a community where you get offended as invitation.

[_kaktus_]

I like an open discussion. And I don't always have to be right.
It would have been different if you had presented all the arguments at the beginning.

We can continue our deliberations, but not here. Because this is not a place for it. Maybe it is worth analyzing the internal diagram of the chip used?

I greet you cordially.

[combat341]

Hallo,
I am new in forum, my A10 is 4 days old but this is my experience:
With orig. FW - 0..254 = FAN OFF, 255 = FAN 100% ON!

With Marlin 2.0 - 0..254 = FAN OFF, 255 = FAN 100% ON!


then I opened the control board - my JP2 jumper was already on
I measured the voltage on fan - 24V.

IT WAS SW (FW) problem

I modified FW : configuration.h (in @section extras)

from

Code: Select all

//#define FAN_SOFT_PWM

to

Code: Select all

#define FAN_SOFT_PWM

now: 0..34 = FAN OFF, 35 = FAN Min ....... 255 = FAN Max ON!


Thats ALL...

[AFewSkroosLoose]

Combat your discovery is great. I have been trying to solve why there is no pwm control of the parts cooling fan and you have found it. Many thanks!