Octopus v1 - 12v not working on FANS

[Lee Schofield]

Hi,    I've fried 3 x 12v FANS, now I discover that even though the jumper is set on the middle jumper to send 12v it still sends 24v to my FANS.  
I'm a bit cross with myself for taking so long to test the voltage with a multi-meter to confirm that the fan pins are pumping out 24v. 

5v works ok, with the jumper on the uppermost pins.  Obviously 24v works, but I can't set them to 12v.

 

Maybe I've caused this damage, whilst frying my 12v FANS, or maybe they have always pumped out 24v.    I'll never know,   but everything else works perfectly.  

 

 

[Lee Schofield]

Hi all,   

I have an Octopus Pro v1.  I'm using the latest Marlin 2.1.2.1

I've fried 3 x 12v FANS, now I discover that even though the jumper is set on the middle two pins to send 12v it still ALWAYS sends 24v to my FANS.  
This appears to be the case for all of the FAN0 through 7 (including the 2 permanent FANS, ie J50 to J56)
I'm a bit cross with myself for taking so long to test the voltage with a multi-meter to confirm that the fan pins are pumping out 24v. 

5v works ok, with the jumper on the uppermost pins.  Obviously 24v works, but I can't successfully set them to 12v.
Maybe I've caused this damage, whilst frying my 3 x 12v FANS, or maybe they have always pumped out 24v.    I'll never know,   but everything else works perfectly.  

Has anyone else had the same problem ?  or even better maybe a solution ?

[Lee Schofield]

I solved this myself, so posting the solution here, to help others in the future.
I had 4 x fans connected in total.  I've discovered that one of these fans (cooling blower) was sending 24v back to the Octopus motherboard, so everything else connected to the 12v fans rail was receiving 24v. 
I discovered the root cause by disconnecting all of the fans, and testing the voltage with a multi-meter, starting with the 2 x permanent fans pins.  These were correct at 12v which matched my 12v pin selection !!!  which was good news, so continuing to test...  I added each other fan one at a time, as soon as I connected the culprit fan, all of the fans incorrectly received 24v.

It turned out to be my blower cooling fan.  Tomorrow, I'll take a closer look at its wiring.   I'm using the original Geeetech A20M wiring loom, I suspect it must somehow be spliced with a 24v connection.
I'm very happy that my Octopus motherboard is working as expected, so I haven't caused damage to it  and I have a way forward using the inbuilt variety of Octopus voltages and I dont need to use any additional buck voltage stepdown boards.

If anyone has the same problem, please test the same, remove all fans, then add them one at a time and test voltages as you progress. 

I hope this helps someone.