No variable speed with fan on D9 RAMPS 1.4

Just connected a cooling fan to my M90 and have it hooked to D9 on my ramps board. M106 S### only turns on the fan if ###>=128 and any value from 128-255 just turns it on full speed. I'd like to get full variable speed control not just binary on/off. I do have the red wire of the fan connected to the + terminal of the ramps board as well.
Wondering if maybe anyone had any insight or bits of knowledge they could drop on me.

Dunno.
Everything you say seems correct to make it work on variable speed

Is it standard Marlin? Is the board defined as MOTHERBOARD BOARD_RAMPS_14_EFB?

Faulty fan, or not 12v . . . ?! Running out of ideas.

The only extra thing I can add is the Slicer's have a setting for what the minimum pulse width needs to be to have the fan turn. Usually something like 50%. It might be good to slice a few parts with Slic3r and tell it to have different speeds for different things and see if it can control the fan speed. If so... you can look at what it is doing and learn from it.

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Ed would
Dunno.
Everything you say seems correct to make it work on variable speed

Is it standard Marlin? Is the board defined as MOTHERBOARD BOARD_RAMPS_14_EFB?

Faulty fan, or not 12v . . . ?! Running out of ideas.

Its the version of Marlin pulled from Nopheads github. Should I try to use standard Marlin?

Fan works fine at full speed but cannot adjust speed. 12v measured across fan terminals while powered.

Edited 1 time(s). Last edit at 03/27/2017 01:17PM by rainswor.

Some fans just will not PWM..

Some can be fixed by adding a capacitor across the fan power inputs

12v fan I meant. I would expect Nopheads Marlin to be sorted for this and would suspect the fan.

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Ed would
12v fan I meant. I would expect Nopheads Marlin to be sorted for this and would suspect the fan.

I have not looked at NopHead's code. But if NopHead is posting code... It is probably very well thought out and it probably works... It's been a while since he has contributed to the Marlin code base, but his finger prints aren't hard to find on it. He knows his stuff!

Edited 1 time(s). Last edit at 03/29/2017 01:12AM by Roxy.