Geeetech PI3B Part fan slows to a stop

I have a Geeetech PI3 ProB (GT2560 RevA+) with Marlin 2.1.2 installed and a part cooling fan added.

The part fan "Hunts" speeding up and slowing down and then gradually slows to a stop while printing following the first M106 command.

Running the fan via Manual Control in Repetier-Host works as expected.

I have written a short script which starts the fan and simultaneously moves the X, Y and Z axis.
If I run this script from Repetier-Host the fan runs continuously whilst moving the axis as it should.

Has anyone else experienced similar behaviour?

Attached are the configuration files being used. Lines commented with RHB are my amendments.

Thanks in advance for help/suggestions.
Roland

There was an issue with the base PWM frequency being set to high on atmel mega2560 in that release.

When turned on full PWM is DC so no frequency issues

Use bugfix 2.1.x or release 2.1.1

Thanks for your help Dust.

Unfortunately both 2.1.1 and 2.1.x show the same issues.
I have also noticed the fan is shown as running at 93% in Manual Control though it has stopped.
If I cancel the print the fan starts running when I home the extruder and has to be turned off manually

Roland

I have now tried release 2.0.7.2 (as it was on my machine) with exactly the same result :-(

Just wiping the egg off my face here :-)
Turns out there was an internal fault on the fan connection which didn't show up when moving the print head in tests.
Moral being test the power supply.
Thanks
R