Duet bed not receiving power
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So i turned on the bed heater using the web interface. The led next to the terminals for the bed turns on. However when measure across the terminals I don't get the 13v I get at vin. I have checked vin and it's 13 volts no minor( 12.9 - 13.2) fluctuations as suggested on the readout on the web interface.
I have just discovered the bed appears to load the rail so much it reports 0 volts. How is that possible, would it not affect the vin voltage as well?
Without the bed connected it reports 13v as expected. I have used ferrules on the cables like prusa have done on vin. I have also used ring terminals on the vin terminal on the bed itself. They're are tight. By ring terminals I mean The ones electricians use on a earth clamp.
I have measured the cable cross sectional area to be 3.3mm. The cable is only short maybe 17 inches. Not very accurate because the cables aren't straight. According to my multimeter, the heater is 0.9 ohms.
So do I need a bigger psu? If so how many watts would you think I need? It's a standard I3 printer just just one hot end and usual steppers and bed
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@ageis, is the Duet crashing when you turn the bed on? If it is then you likely have insufficient power produced by the power supply. If the Duet is not crashing then the next suspect would be the fuse that is on the Duet that protects the bed circuit. If that fuse is OK then it could be the FET that does the switching.
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@jens55 omg it might be the fet. The fuse next to the bed connector is fine.
If that's the right fuse. It's the only fuse I can see that could be a bed fuse. The other two are too small.
So does anyone know of a place in Manchester that does this sort of board level repair? I can't do smd work. The last time I tried, it was a complete write off. We all know the duet isn't a cheap board. So I think it'll be worth to repair it. As long as the repair shop doesn't ask for silly prices to replace a 2 quid fet. It should be straight forward for them to replace. There's schematics too so its not like they need to spend time finding the fet.
It's probably damage from the short circuit accident I had a few months ago. It appeared to still work afterward though. It's given up.
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It's probably damage from the short circuit accident I had a few months ago. It appeared to still work afterward though. It's given up.
I have found (the hard way) that shorting FET outputs is a pretty reliable way to kill the FET
I am surprised that it still appeared to work afterwards but I suppose it could be a case of it getting damaged and eventually failed completely.
The FET is much faster than the fuse so the fuse will not protect the FET. -
@jens55 Thats sad. Am just curious would a poly fuse be any better?
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Just as an FYI - it might be cheaper to just use a different output and run it through an external SSR. Of course a standard relay would work as well (reduced lifetime?) but depending on which output you use, you might need a flyback diode.
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@jens55 how would that tie in with the control logic? The firmware needs to know it's not on that output anymore?
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@ageis yes, you will need to adjust your config.g file accordingly. Post your config.g file and hopefully somebody better at interpreting things will tell you how config.g needs to be tweaked.
Please provide info of the hardware and firmware you are using as that will affect things. Please also post what I/O ports are available. For example, if you have a single hot end, you are likely using E0Heat to power that hot end and you might have E1Heat available for the bed heater. Another choice would be a fan output if you have one that is open.
These comments are mostly about a Duet2wifi as that is what I last played with. If you have a Duet3 6HC you would have different ports and different ways of configuring things. -
; Configuration file for Duet WiFi (firmware version 3.3) ; executed by the firmware on start-up ; ; generated by RepRapFirmware Configuration Tool v3.3.16 on Sun Jul 23 2023 20:00:34 GMT+0100 (British Summer Time) ; General preferences G90 ; send absolute coordinates... M83 ; ...but relative extruder moves M550 P"prusa" ; set printer name ; Network M552 P0.0.0.0 S1 ; enable network and acquire dynamic address via DHCP 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 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 X100.00 Y100.00 Z400.00 E161.3 ; set steps per mm M566 X900.00 Y900.00 Z12.00 E120.00 ; set maximum instantaneous speed changes (mm/min) M203 X6000.00 Y6000.00 Z1000.00 E1200.00 ; set maximum speeds (mm/min) M201 X500.00 Y20.00 Z400.00 E250.00 ; set accelerations (mm/s^2) M906 X800 Y800 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 X250 Y190 Z210 S0 ; set axis maxima ; Endstops M574 X1 S1 P"xstop" ; configure switch-type (e.g. microswitch) endstop for low end on X via pin xstop M574 Y1 S1 P"ystop" ; configure switch-type (e.g. microswitch) endstop for low end on Y via pin ystop M574 Z1 S2 ; configure Z-probe endstop for low end on Z ; Z-Probe M558 P1 C"zprobe.in+zprobe.mod" H10 F120 T6000 ; set Z probe type to unmodulated and the dive height + speeds G31 P500 X230 Y9 Z5.35 ; set Z probe trigger value, offset and trigger height M557 X15:235 Y15:190 S20 ; define mesh grid ; Heaters M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; 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 B4138 ; 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 H1 T45 ; set fan 1 value. Thermostatic control is turned on ; Tools M563 P0 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 definedBe grateful if someone can tell how to reconfigure the heated bed control pin to a different pin.
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@ageis said in Duet bed not receiving power:
M950 H0 C"bedheat" T0
Which pin do you want to use instead?
Find the pin you want to use and look up it's name here: https://docs.duet3d.com/en/Duet3D_hardware/Duet_2_family/Duet_2_WiFi_Ethernet_Hardware_Overview#pin-names
Then replace "bedheat" with that pin name.
