Heatbed Automatically Starting?



  • Hi Again!
    I'm trying to avoid spamming up these forums by reading as much as possible but i'm finding myself struggling to get some information. That aside, i've got an issue with my heatbed.

    I've wired everything up now (once i had confirmed i could home all axes and generally that everything except heating worked), and have found that upon powerup, my heatbed starts. It rapidly approaches 60deg, at which point i decided this probably wasn't normal behavior and turned it off.

    My first thought was that this was a short, so i've turned it off and looked it over, but haven't found anything which would normally suggest a short. Anyone experienced something similar? Have i botched something? I went over my config.g and didn't find anything of relevance to the heatbed specifically, i will attach below however incase i missed something.

    Cheers,
    Shiven

    [[language]]
    ; Configuration file for Duet WiFi (firmware version 1.17)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Sat Jul 22 2017 23:44:03 GMT+0000
    
    ; 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
    
    M667 S1 ; Select CoreXY mode
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X200 Y190 Z155 S0 ; Set axis maxima
    
    ; Endstops
    M574 X1 Y1 Z1 S0 ; Define active low and unused microswitches
    M558 P0 X0 Y0 Z0 H5 F120 T6000 ; Set Z probe type to switch, the axes for which it is used and the probe + travel speeds
    G31 P600 X0 Y0 Z2.5 ; Set Z probe trigger value, offset and trigger height
    M557 X15:185 Y15:175 S20 ; Define mesh grid
    
    ; Drives
    M569 P0 S0 ; X Goes Forwards
    M569 P1 S1 ; Y Goes Backwards
    M569 P2 S0 ; Z Goes Backwards
    M569 P3 S1 ; Drive 3 goes forwards
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X87.489 Y87.489 Z4000 E420 ; Set steps per mm
    M566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
    M203 X6000 Y6000 Z180 E1200 ; Set maximum speeds (mm/min)
    M201 X500 Y20 Z250 E250 ; Set accelerations (mm/s^2)
    M906 X1400 Y1400 Z1400 E1400 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout
    
    ; Heaters
    M143 S260 ; Set maximum heater temperature to 260C
    M305 P0 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 0
    M305 P1 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 1
    
    ; 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
    
    ; Network
    M550 PHypercube ; Set machine name
    M552 S1 ; Enable network
    M586 P0 S1 ; Enable HTTP
    M586 P1 S1 ; Enable FTP
    M586 P2 S0 ; Disable Telnet
    
    ; Fans
    M106 P0 S0.3 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 S1 I0 F500 H1 T45 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Custom settings are not configured
    
    


  • MOSFET died short most probably.



  • So a small update (i'm still trying to figure this out). I've flicked it on and tried to run it to 0, when that failed tried holding it at 60. It kept going well past 60 so i flicked it off.

    I'm feeling like the FET on the board is suspect. Is there a way to bypass said FET and run it off E1; alternatively, whats the difficulty level in replacing the fet? I'm confident of my soldering skills but less enthused by causing more damage…



  • @sigxcpu:

    MOSFET died short most probably.

    Ah apologies i was still writing it when you said so. I tend to agree, i'm not sure how to solve it though.


  • administrators

    1. With the bed heater disconnected, does the bed heat LED turn on as soon as you apply VIN power to the board?

    2. Do you have the bed heater connected directly to the bed heater output terminals, or some other arrangement?

    3. What sort of bed heater are you using, and what VIN voltage are you using?

    4. How long have you had the board? Your supplier may be prepared to replace it under warranty.



  • @dc42:

    1. With the bed heater disconnected, does the bed heat LED turn on as soon as you apply VIN power to the board?
    No, Light doesn't come on at all, unless heat bed is connected

    2. Do you have the bed heater connected directly to the bed heater output terminals, or some other arrangement?
    Connected directly to the output terminals.

    3. What sort of bed heater are you using, and what VIN voltage are you using?
    I believe it is a prusa heatbed mk 2. Red, standard aluminium(?) platter. Quite old (6 years?). VIN voltage is 12V off a standard ATX PSU (quite literally pulled from my old ramps board into my new Duet Wifi.

    4. How long have you had the board? Your supplier may be prepared to replace it under warranty.
    4 Days, though i imported it from England so its going to be difficult to do any sort of swap over. (I am Australian)

    Thanks for all the help thus far, seems like i'm looking at doing a changeover.



  • Scratch this entire post, apologies, my board appears to be playing fine now. I plugged the connectors back in (after removing in the first step) and its not going crazy anymore.

    I don't have a reason why, but its working. Apologies on that.


  • administrators

    @Shiven:

    1. With the bed heater disconnected, does the bed heat LED turn on as soon as you apply VIN power to the board?
    No, Light doesn't come on at all, unless heat bed is connected

    That indicates a short between one of your bed heater connections and ground. If the problem was the mosfet on the Duet, the LED would be lit even without the bed heater connected.



  • Hi,

    I'm having the same problem that this person originally reported. I have done a modest amount of printing, and I am accustomed to the heated bed staying cold on start, with no activity on bed heat LED until I kick things into gear. Furthermore, that light would rapidly flash as the PWM did it's thing. Now, I get instant-on, and "M140 S0" has no impact – just keeps on heating. Temperature readings appear correct, at least :)?

    Answering your questions:
    1. With the bed heater disconnected, does the bed heat LED turn on as soon as you apply VIN power to the board?
    Yes.

    2. Do you have the bed heater connected directly to the bed heater output terminals, or some other arrangement?
    Yes. There is an inline thermal fuse, but thus far hasn't been tripped.

    3. What sort of bed heater are you using, and what VIN voltage are you using?

    I'm using a 24V MK2A 300x300 bed:
    TriGorilla 3D Printer MK2A Aluminum Heatbed Hot Plate Power Supply 24V RAMPS 1.4 For RepRap Prusa Mendel 3003003mm
    VIN is 24V from a Meanwell PS (MSP-600-24).

    4. How long have you had the board? Your supplier may be prepared to replace it under warranty.
    April 2017 from Filastruder.

    Configuration below. Thanks for all your help.

    Rob

    ; Configuration file for Duet WiFi (firmware version 1.19.2)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Thu Jul 20 2017 18:24:16 GMT-0500 (CDT)
    
    ; 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
    
    M667 S1 ; Select CoreXY mode
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X320 Y285 Z335 S0 ; Set axis maxima
    
    ; Endstops
    M574 X1 Y2 Z0 S0 ; Define active low and unused microswitches (Z1 if using that endstop!)
    
    ; Drives
    M569 P0 S0 ; Drive 0 (X) goes backwards (1.19)
    M569 P1 S0 ; Drive 1 (Y) goes backwards (1.19)
    M569 P2 S0 ; Drive 2 (Z) goes backwards
    M569 P3 S1 ; Drive 3 goes forwards
    M569 P4 S0 ; Drive 4 (3rd Z) goes backwards
    
    M584 X0 Y1 Z2:4 E3 ; Map drives (as above)
    
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X100 Y100 Z400 E837 ; Set steps per mm
    M566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
    M203 X7200 Y7200 Z365 E1200 ; Set maximum speeds (mm/min)
    M201 X500 Y500 Z250 E300 ; Set accelerations (mm/s^2)
    M906 X1000 Y1000 Z1000 E800 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout
    
    ; Heaters
    M143 S260 ; Set maximum heater temperature to 260C
    
    M307 H0 A67.9 C260.8 D2.5 S0.80 B0 ; Set PID controls with new (M307) parameters, calculated for 80% PWM max.
    M307 H1 A337.6 C147.4 D4.5 S1.00 B0 ; Set PID controls with new (M307) paramters, calculated for 100% PWM and 250C.
    M305 P0 T100000 B4138 C0 R4700 L0 H0 ; Set thermistor + ADC parameters for heater 0 (bed)
    M305 P1 T100000 B4725 C7.06e-8 R4700 L0 H0 ; Set thermistor + ADC parameters for heater 1 (hotend) (from E3D documentation for RepRap > 1.17)
    
    ; Tools
    M563 P0 D0 H1 F0; Define tool 0 to be D (drive) 0, H (heater) 1, and F (active cooling fan) 1
    G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
    G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C
    
    ; BL Touch
    M307 H3 A-1 C-1 D-1              ; reserve pin 8 (Heater 3 PWM) for BL Touch
    M558 P5 X0 Y0 Z1 H4 F200 T800 R1 ; type 5, use for Z, Feed rate 200 mm/min, 
                                     ; dive Height 4mm, Travel speed 800 mm/min, wait 1s (R) before dive
    G31 X-8 Y-41 Z1.46 C0 S0 P25\.    ; this Z has me using a +0.15mm Z offset in Slic3r for PETG
    M557 X30:240 Y20:240 S42         ; S35 is 7 points in each axis. S42 is 6 in each axis.
    M280 P3 S160 I1                  ; reset probe error state
    M280 P3 S90 I1                   ; retract
    
    ; Network
    M550 PBigBoy ; Set machine name
    ;M552 S0 ; Disable network
    M552 S1 ; Enable network
    M552 P192.168.1.120  ; Set the IP address
    M553 P255.255.255.0  ; Set netmask (Subnet Mask)
    M554 P192.168.1.254  ; Set the gateway (Default Gateway)
    ;
    ; Access point is configured manually via M587 by the user, info stored in ESP8266 (not config files)
    ; M586 P0 S1 ; Enable HTTP
    ; M586 P1 S0 ; Disable FTP
    ; M586 P2 S0 ; Disable Telnet
    
    ; Fans
    ; NOTE: P0 is set (above) to be active cooling for tool 0 (which is also default).
    ; NOTE: P1 is thermostatically controlled and left alone by slicer (I hope).
    ;
    M106 P1 S1 I0 F500 H1 T45; Set fan 1 (hotend) value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P0 S1 I0 F500 H-1; Set fan 0 (active cool) value, PWM signal inversion and frequency. Thermostatic control is turned off
    ; M106 P2 S1 I0 F500 H1 T45 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Custom settings are not configured
    
    

  • administrators

    It sounds like either the bed heater mosfet or the driver has failed. These are both very unusual faults. Forum user W3DRK does Duet repairs and is based in the US, so you could send him a PM.



  • Thanks; I've sent a note to Dieter (W3DRK).

    Just for my own knowledge, is there a convenient way to map heater 2 (which I understand is an extruder heater and not meant for high current) as the bed heater and then use it to control a DC-DC SSR? Just thinking through my options; apologies if that's stupid for some reason that isn't obvious to me.

    EDIT: The M305 X parameter seems to play a role, but that isn't the whole story.

    Thanks!


  • administrators

    You can use the M140 H parameter to assign the bed heater to a different heater number.



  • Thanks!



  • Dieter confirms bed heater MOSFET was fried; board is on the way back home. Thanks Dieter :).


  • administrators

    @paralepsis:

    Dieter confirms bed heater MOSFET was fried; board is on the way back home. Thanks Dieter :).

    That's the first time I have heard of that happening. Maybe it was just a case of a bad mosfet, all the same I suggest you check your bed heater wiring carefully for possible shorts.



  • Printer back up and running, switched over to an Auber SRDD80-5F for managing bed power. All seems well. No obvious problems with the wiring.


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