Trouble powering part cooling fan

  • Hi,

    My part cooling fan decided to blow itself to bits last night. I thought it would be simple to swap it for a new but for some reason it won't power up.

    I quick meter reading says I am getting 24v out of the pins on startup of the duet. Shouldn't it read 24v?

  • I'm measuring the 2 pins on fan2

  • By default Fan 0 is the part cooling fan. Did you have Fan 2 configured to work as the tool fan before?

    I'm confused by your first post. You said you are getting 24v, is that not what you'd expect?

  • My config should be good to go as the only thing that has changed is that I have fitted a new fan.

    I wouldn't expect 24v until I send the gcode to turn the fan on. Or is that assumption incorrect?

  • Can you post your config?

    How did the fan blow up?

    If your config is correct the problem is beyond me. Sorry.

    I think you may have a shorted fan header?

  • I'm away from my printer at the moment but the config is fine as i've been printing for the last 6 months on the same config.

    Judging by the way the fan exploded, I can only assume a fault with the blades or a jam. I wasn't around when it happened.

    I guess my questions are:

    a) how do I measure the board to ensure it's not shorted
    b) how can I test if the replacement fan is also faulty

  • Hi @totalitarian,

    Just thought I'd chime in and note that to the best of my knowledge the power control of the fan connectors on the Duet is done by toggling the ground pins rather than the VCC pins.

    So assuming you are indeed measuring the 2 pins on the connector itself (VCC & GND) - and not taking GND from somewhere else when measuring the voltage on the VCC pin - then it sounds to me that @Phaedrux's guess about a shorted fan header is the most likely explanation (it would also explain why the previous fan failed).

    To check if there's a short or not in the fan header, completely disconnect the board from the power supply and switch your multimeter to measuring the minimal amount of resistance it can. Then touch the 2 fan connector pins with the 2 multimeter probes. The reading ought to be '1' meaning 'open circuit' . On the other hand, if you get any positive value when reading the resistance, then there's a short.

    To test the fan itself, you can connect it to a separate power supply with the correct voltage. Alternatively, you can also connect it to one of the two 'always on' fan connectors on the Duet and see if it runs as expected.

    Hope this helps.

  • Ok the fan works perfectly fine when connected to the always on pins. When I measure the reading on fan 2 pins, it stays at 1 as suggested. I guess that means there is no short?

  • Is it possible to use one of the always on fans as a part cooling fan? Basically fan0 & fan2 appear to be dead.


    I don't know how to turn them on via gcode...

  • It would help to know how you have them configured in config.g

  • Here you go

    E; Configuration file for Duet WiFi (firmware version 1.20 or newer)
    ; executed by the firmware on start-up
    ; generated by RepRapFirmware Configuration Tool on Sun Dec 17 2017 21:18:18 GMT+0000 (GMT Standard Time)

    M551 Pv1deoworld ; machine password
    ; General preferences
    M111 S0 ; Debugging off
    G21 ; Work in millimetres
    G90 ; Send absolute coordinates...
    M83 ; ...but relative extruder moves
    M555 P2 ; Set firmware compatibility to look like Marlin
    ; Automatic saving after power loss is not enabled

    M667 S1 ; Select CoreXY mode
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X300 Y275 Z300 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y2 Z1 S0 ; Set active high endstops
    M558 P0 H5 F600 T6000 ; Set Z probe type to switch and the dive height + speeds
    G31 P600 X0 Y0 Z2.5 ; Set Z probe trigger value, offset and trigger height
    M557 X15:285 Y15:270 S20 ; Define mesh grid

    ; Drives
    M569 P0 S1 ; Drive 0 goes forwards
    ;M569 P1 S0 ; Drive 1 goes forwards
    M569 P2 S0 ; Drive 2 goes forwards
    M569 P3 S0 ; Drive 3 goes forwards
    M569 P4 S1 ; Drive 4 goes forwards
    M584 X4 Y1 Z2 E3
    M350 X16 Y16 I1; Configure microstepping with interpolation
    M350 Z16 E16 I1 ; Configure microstepping without interpolation
    M92 X80.203 Y80.203 Z1122.854 E412 ; Set steps per mm
    M566 X330 Y330 Z90 E1500 ; Set maximum instantaneous speed changes (mm/min)
    M203 X12000 Y12000 Z600 E4000 ; Set maximum speeds (mm/min)
    ;M203 X20000 Y20000 Z600 E4000 ; Set maximum speeds (mm/min)
    M201 X800 Y800 Z15 E3000 ; Set max accelerations (mm/s^2)
    M906 X1200 Y1200 Z1200 E960 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout

    ; Heaters
    M307 H0 A141.2 C597.9 D0.7 S1.00 V24.4 B0
    M305 P0 T100000 B4725 R4700 ; Set thermistor + ADC parameters for heater 0
    M143 H0 S120 ; Set temperature limit for heater 0 to 120C
    ;M305 P1 T100000 B4725 C7.06e-8 R4700 ; Set thermistor + ADC parameters for heater 1
    M305 P1 X200
    M143 H1 S280 ; Set temperature limit for heater 1 to 280C
    M307 H1 A390.0 C198.6 D10.5 S1.00 V24.4 B0

    ; Tools
    M563 P0 D0 H1 F2; Define tool 0
    G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
    G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C

    ; Network
    M550 Gecko ; Set machine name
    M552 S1 ; Enable network
    M587 S"xxx" P"xxx" ; Configure access point. You can delete this line once connected
    M586 P0 S1 ; Enable HTTP
    M586 P1 S1 ; Enable FTP
    M586 P2 S1 ; Enable Telnet

    ; Fans
    M106 P0 S0 I0 F500 H-1 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P2 S0 I0 F500 H-1 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned off

    ; Custom settings are not configured

    ; Miscellaneous
    T0 ; Select first tool

    M307 H3 A-1 C-1 D-1 ;
    M558 P5 X0 Y0 Z1 H5 F120 T2000; F probe speed - T Travel speed
    G31 X37 Y0 Z1.1 P5
    M557 X37:263 Y37:263 S75.3 ; probe from X=30 to 270, Y=30 to 270mm with a mesh spacing of 80mm

    ;Allow moving of axis without the need to home
    M564 H0

  • administrators

    @totalitarian the always on pins are hard wired into the power so they run all the time at fullmpower so not necessarily appropriate for part cooling. They can be fine for hotend cooling if you are happy to have the hotend cooling fan on all the time.

  • I think that is the way I have to go. Always on for the hotend fan and fan 1 for part cooling

  • administrators

    @totalitarian said in Trouble powering part cooling fan:

    I think that is the way I have to go. Always on for the hotend fan and fan 1 for part cooling

    Either that, or get the blown fan mosfets replaced.

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