Printrbot Talk Forum

Hello,

I have an PrintrBoard Rev. D laying around and want to give it a try on my current build.
I have two 5V fans (2 wires) for layer cooling and I wonder how or if I could connect these to my Printrboard.
I only see one fan (2pin) connector which is 12V I guess for hotend cooling.
Then there are two EXP slots (EXP1 + EXP2). I guess they only deliver 5v for logic.
Else I only see those endstop connectors of which I would only need XYZ. E endstop delivers 5V I guess. But again only for logic and not for driving a 5V 0.15A fan.

So, is it possible to drive two 5V 0.15A layer cooling fans with this board? They should be controllable by the firmware when cooling overhangs and the like.

On a Rev D board, the connection for the fan is speed-controlled for part cooling. Fans for cooling hot ends came along later. But the bottom line is you will need to get creative if you want to run a hot end cooling fan continuously from 12V. As in figure out a way to pick up the 12V from somewhere off the board. It's easy if you are using an ATX power supply because there are unused connectors. Yellow is +12V; Black is Common (or "ground").

If you're electronics savvy...you can solder leads from backside of the printrboard (backside of the 6pin atx connector) and run that to a mosfet in conjunction with a pin from one of the expansion headers to turn the mosfet on and off. You would then configure Marlin to use the expansion pin to control the fan.

Thanks for your answers.

I forgot that the fan labeled pin is for part cooling. That's interesting. I can hook up a step-down converter to the fan pin and the 5V cooling fan on the other end.
Then use an expansion pin to switch the mosfet on and off as cbxbiker said.
I will think about that.

Okay so regarding my creativity on solving this issue...well, I am not that creative currently. So I decided to push the 5V fan setup back and concentrate on the core functionality.
Which is to run my e3d v6 hotend just with a hotend cooling fan and no print cooling fan.

RetireeJay, you said that the FAN connector on the Rev. D board is software controlled for part cooling. Am I able to route my hotend fan via firmware (Marlin 1.1.9) to be driven by that pin when the hotend goes above 50°C?
In Marlin there is #define E0_AUTO_FAN_PIN [INSERT_PIN_NUMBER]. This enables auto fan control for the hotend.
Theoretically, when inserting the pin number of the FAN connector on the printrboard REV. D the firmware could switch on the hotend fan automatically when the temperature goes above 50°C.
Can you confirm that this is correct?

I found a thread about pin mapping in this forum and a link to a google docs
viewtopic.php?p=32001#p32001

I am assuming this is the pin mapping for a Rev D because I want to assume it
So it says :
Fan FAN_SOFT_PWM | FAST_PWM_FAN /PWM-FAN 41
Then 41 is the pin number for controlling the FAN connector.

I, or better said the firmware, should be able to control the hotend fan automatically when I define #define E0_AUTO_FAN_PIN 41 in Marlin's Configuration.h.
I will test this and report back for completness.

Good luck. The one code I've never been able to crack is the correlation between "logical" pin numbers in Marlin and physical pin numbers.
But normal unmodified Marlin configured for the Printrboard uses the Fan connector for proportional speed control (part cooling). If you want to use that connector for extruder body cooling with that 50C threshold, you'll have to disable the existing code as well as enable your new code.