@fcwilt Yes, I am using PID mode. After replacing the fuse it did heat up just fine the first time and sustained a temp around 90C to complete a PID autotune. I received the faults when I then tried to run off a print afterward.

I've soldered the wires to the bed and was able to heat it again and begin a print. I suspect the issue was probably due to the cruddy connection where the wires enter the bed probably adding a bit of resistance there. My bed and hot end sensors now give matching readings at room temp whereas before they were at least a few degrees apart so this theory seems to check out so far.

Thanks again.

@fcwilt Yes, I am using PID mode. After replacing the fuse it did heat up just fine the first time and sustained a temp around 90C to complete a PID autotune. I received the faults when I then tried to run off a print afterward.

I've soldered the wires to the bed and was able to heat it again and begin a print. I suspect the issue was probably due to the cruddy connection where the wires enter the bed probably adding a bit of resistance there. My bed and hot end sensors now give matching readings at room temp whereas before they were at least a few degrees apart so this theory seems to check out so far.

Thanks again.

I am using a 24V PSU so I will plan to add the fet while I am doing my other upgrades.

The faults stated the bed was not heating as fast as expected.

Thanks for the help!

I do not know off hand how much current it is supposed to draw but I am measuring 1.4 ohms on the bed.

I'm linking below to a bed heater that is sold as a replacement for the black widow but I think this one would be an upgrade for my machine which is likely part of the issue at hand. My widow is an early version that came with a PCB heatbed and before they started shipping with the mosfet, as I said before. The stock connector that came with the kit has always been a little shoddy with voltage and ground split over four wires. There was a reason they started shipping them with mosfets afterall. I know one popular mod is to solder the wires directly to the bed for a better connection so I will start there but I wonder if I should still plan to add a mosfet if I want to use my current heated bed with the Duet.

I was able to run a PID autotune and heat the bed up 90C without burning out the new fuse, however each subsequent attempt at heating the bed has so far resulted in a fault.

https://keenovo.store/products/keenovo-silicone-heater-250mm-x-400mm-for-tevo-black-widow-3d-printer-build-plate-heatbed-heating-upgrade

@fcwilt well now I feel just a little dumb.. The fuse is the issue.

Now I wonder what should be done moving forward? I know the black widows started shipping with an external mosfet at some point after I purchased mine but I never installed one. I read some posts from other black widow users on the forum that didn't seem to think the external mosfet was necessary, but if I tripped the fuse presumably on the first attempt at heating the bed I wonder will it be safer to install an external mosfet?

Thanks for the help.

@Veti the heated bed was working with the stock MKS gen 1.4 board.

I upgraded the firmware on the duet before setting it up so I did not try the heated bed with the older firmware.

Config file below. So far I've tried with both PID and bang bang mode set for the bed. Thanks.

; Configuration file for Duet WiFi (firmware version 3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.2.2 on Fri Jan 22 2021 13:40:37 GMT-0500 (Eastern Standard Time)

; General preferences
G90                                                    ; send absolute coordinates...
M83                                                    ; ...but relative extruder moves
M550 P"Sulla"                                          ; set printer name

; Network
M552 S1                                                ; enable network
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 S0                                             ; physical drive 1 goes backwards
M569 P2 S0                                             ; physical drive 2 goes backwards
M569 P3 S1                                             ; physical drive 3 goes forwards
M584 X0 Y1 Z2 E3                                       ; set drive mapping
M350 X16 Y16 Z16 E16 I1                                ; configure microstepping with interpolation
M92 X80.00 Y80.00 Z1600.00 E837.20                     ; set steps per mm
M566 X900.00 Y900.00 Z60.00 E120.00                    ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00                ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00                    ; set accelerations (mm/s^2)
M906 X1000 Y1000 Z800 E800 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 X370 Y250 Z300 S0                                 ; set axis maxima

; Endstops
M574 X1 S1 P"!xstop"                                   ; configure active-high endstop for low end on X via pin !xstop
M574 Y1 S1 P"!ystop"                                   ; configure active-high endstop for low end on Y via pin !ystop
M574 Z1 S1 P"!zstop"                                   ; configure active-high endstop for low end on Z via pin !zstop

; Z-Probe
M558 P0 H5 F120 T6000                                  ; disable Z probe but set dive height, probe speed and travel speed
M557 X15:215 Y15:195 S20                               ; define mesh grid

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4092         ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0                                  ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B1 S1.00                                       ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0                                                ; map heated bed to heater 0
M143 H0 S120                                           ; set temperature limit for heater 0 to 120C
M308 S1 P"e0temp" Y"thermistor" T100000 B4725 C7.06e-8 ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1                                   ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 B0 S1.00                                       ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S280                                           ; set temperature limit for heater 1 to 280C

; Fans
M950 F0 C"fan0" Q500                                   ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H-1                                         ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"fan1" Q500                                   ; create fan 1 on pin fan1 and set its frequency
M106 P1 S1 H-1                                         ; set fan 1 value. Thermostatic control is turned off

; Tools
M563 P0 S"E0" D0 H1 F0                                 ; 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

; Custom settings are not defined

I am working to upgrade my Tevo Black Widow with Duet 2 Wifi running RRF 3.2

I am having an issue that I am not getting any response when trying to heat or tune the bed heater. No change in temperature at all. I put my voltmeter on the terminals when the bed should be heating and reads only around 1v. Since the bed is stock I'm not sure I've entered the correct parameters when setting up firmware in the RepRap configuration tool, but I would expect there to be more current there regardless. Did I miss something in the configuration? Are there some steps I should take to troubleshoot the Duet board itself?

Any input is greatly appreciated. Thanks.