Fans running only when tool is inactive

  • Possibly a stupid question, but I have a 24v system using an E3D V6 with it's stock 24v 30mm fan and a part fan that is a 24v 50mm blower. I'm having a problem where the fans only run when the hot end is inactive. When I power up the system, the hot-end fan runs 100% and the part fan is off - as expected. However, when I activate the hot-end, the hot-end fan immediately stops. This happen whether the hot-end fan is plugged into an always-on connection or in one of the controllable connections. Any ideas why this is happening and how to fix it would be greatly appreciated. Using a Duet2 Wifi, firmware 2.01, config code below...

    ; Configuration file for Duet WiFi (firmware version 1.21)
    ; executed by the firmware on start-up
    ; generated by RepRapFirmware Configuration Tool v2 on Sun Jun 09 2019 20:10:50 GMT-0400 (Eastern Daylight Time)

    ; General preferences
    G90 ; Send absolute coordinates...
    M83 ; ...but relative extruder moves

    ; Network
    M550 P"Duet A30" ; Set machine name
    M552 S1 ; Enable network
    M587 S"XXXX" P"1234567890" ; Configure access point. You can delete this line once connected
    M586 P0 S1 ; Enable HTTP
    M586 P1 S0 ; Disable FTP
    M586 P2 S0 ; Disable Telnet

    ; Drives
    M569 P0 S1 ; Physical drive 0 goes forwards
    M569 P1 S1 ; Physical drive 1 goes forwards
    M569 P2 S1 ; Physical drive 2 goes forwards
    M569 P3 S0 ; Physical drive 3 goes backwards
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X80.00 Y80.00 Z400.00 E415.00 ; Set steps per mm
    M566 X600.00 Y600.00 Z30.00 E600.00 ; Set maximum instantaneous speed changes (mm/min)
    M203 X9600.00 Y9600.00 Z1800.00 E3000.00 ; Set maximum speeds (mm/min)
    M201 X3000.00 Y3000.00 Z50.00 E2000.00 ; Set accelerations (mm/s^2)
    M906 X800.00 Y800.00 Z800.00 E800.00 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout

    ; Axis Limits
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X320 Y320 Z420 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y1 S1 ; Set active high endstops

    ; Z-Probe
    M574 Z1 S2 ; Set endstops controlled by probe
    M307 H4 A-1 C-1 D-1 ; Disable heater on PWM channel for BLTouch
    M558 P9 H5 F120 T6000 ; Set Z probe type to bltouch and the dive height + speeds
    G31 P500 X48 Y-2 Z1.75 ; Set Z probe trigger value, offset and trigger height
    M557 X20:300 Y20:300 S40 ; Define mesh grid

    ; Heaters
    M307 H0 B0 S1.00 ; Disable bang-bang mode for the bed heater and set PWM limit
    M305 P0 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 0
    M143 H0 S120 ; Set temperature limit for heater 0 to 120C
    M305 P1 T10000 B1504 C7.060000e-8 R4700 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S285 ; Set temperature limit for heater 1 to 285C

    ; 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 T100 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on

    ; Tools
    M563 P0 D0 H1 ; 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

    ; Automatic saving after power loss is not enabled

    ; Custom settings are not configured

  • administrators

    Are both the red and black wires form the the fans connected directly to the fan outputs? You would get that symptom if you shared the positive wire ot the extruder heater with the positive wires to the fans, but you picked the wrong heater wire to share.

  • I know the hot-end fan is using both ground and power directly. The part fan may be sharing power in that I’m using the pcb connection board from the Geeetech A30 and it shares for the part fan. I’ll try bypassing the pcb completely and see how that does. Appreciate the response!

  • Okay, so I've run wires directly from the fans to the board. When I connect a fan to the "always on" it runs. When I connect a second fan to the second always on and turn on the power, the fuse blows. If I have one fan on the always on and one one a PWM connection, the always on runs, the PWM is idle, and when I make the hot end active and set a temp, the fuse blows. I've tried multiple fans in multiple configurations so I'm pretty positive it's not the fans or the connection wiring. Have I damaged the board somehow? Any thought would be greatly appreciated!

  • administrators

    @pkirill said in Fans running only when tool is inactive:

    When I connect a second fan to the second always on and turn on the power, the fuse blows.

    Do you have the red and black wires the right way round? If you do then that second fan is probably faulty. I am assuming that they are not very powerful fans such that the combined total load is well over 1A.


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