Geeetech i3 Prusa Pro B fans don't work

[molekuul]

Hi,

I just build my Geeetech i3 Prusa Pro B, it came with two 2 wire fans, however they don't work. Both fans have 3 pin connector, with only the red and black wire connected. I connected the fans at Fan1 for the extruder, and Fan3 for the boardcooling fan.

What can I do to get these fans working as they should?


Kind regards,

Joris Weijters

[William]

I think you should replace the "Q5"--- AP2306AGN

[molekuul]

Hi Wiliam,

I thought from the schematic Q5 is only for the PWM Fan
not for the 12volt fans.

Kind regards

Joris

[molekuul]

Hi,

I measured the output of the 7812, ther is no power at the output.
There is 12Volt at the input of the 7812.
This normaly means, it's defective, or there is a short circuit behind this 7812.
What is behind the the 7812? Other than the Fans?

Kind regards,

Joris Weijters

[molekuul]

Hi William,


I found the problem. There was an short circuit between the + and the - of fan3!
see picture below
https://i.imgur.com/wcmbzEV.jpg


I insert the jumper, now my fans work

I removed Q4 and the 7812
I still don't know what Q4 is needed for.

Kind regards,

Joris Weijters

[William]

Q4 is for
No matter PSU is 24V or 12V
The output interface of fan voltage is 12V also