Error: MINTEMP triggered, system stopped! Heater_ID: 0

Well I’ve fought this all week and I’m stumped. I thought I blew my Mini’s Rambo board when I accidentally pulled the wires out of the Titan Aero’s thermister while cleaning off some nylon filament gooped onto the nozzle and wires while heated. I didn’t hear any pop or smell smoke or anything. I was able to remove the filament and change to another filament and extrude a bit to purge out the old filament, but when I shut done the printer and turned it back on and tried to connect to Octoprint it would connect, then shut down with a MinTemp Error:

Recv: FIRMWARE_NAME:Marlin FIRMWARE_VERSION:1.1.5.64 EXTRUDER_TYPE:SingleExtruder SOURCE_CODE_URL:https://code.alephobjects.com/diffusion/MARLIN PROTOCOL_VERSION:1.0 MACHINE_TYPE:LulzBot Mini EXTRUDER_COUNT:1 UUID:351487b6-ca9a-4c1a-8765-d668b1da6585
Recv: Cap:EEPROM:1
Recv: Cap:AUTOREPORT_TEMP:1
Recv: Cap:PROGRESS:0
Recv: Cap:PRINT_JOB:1
Recv: Cap:AUTOLEVEL:1
Recv: Cap:Z_PROBE:1
Recv: Cap:LEVELING_DATA:1
Recv: Cap:SOFTWARE_POWER:0
Recv: Cap:TOGGLE_LIGHTS:0
Recv: Cap:CASE_LIGHT_BRIGHTNESS:0
Recv: Cap:EMERGENCY_PARSER:1
Recv: ok N1 P15 B3
Send: M21
Recv: ok P15 B3
Send: M155 S2
Recv: ok P15 B3
Recv: T:0.00 /0.00 B:0.07 /0.00 @:0 B@:0
Recv: Error:MINTEMP triggered, system stopped! Heater_ID: 0
Changing monitoring state from ‘Operational’ to 'Error: MINTEMP triggered, system stopped! Heater_ID: 0

Recv: Error:Printer halted. kill() called!

I got the same MinTemp Error when trying to connect via USB in Cura 2.63. I talked to Lulzbot support and they said the Rambo wasn’t blown but there was probably a break in the cables somewhere between the thermister and the board. I checked the thermister and heater cables as best I could and could not find any obvious problems in the cables. I also checked them with my multimeter and they have signal. I even ran some new wires to the heater and thermister just to be sure and still I get the MinTemp error. Am I missing something? Maybe the Rambo is damaged. It seems to function, but just keeps triggering the Min Temp error. I even reflashed the the firmware, reflashed it again with an older version, and reflashed it with the newest firmware, and still get the same error. The board responded while flashing and Cura reported successful firmware upgrades each time.

I’m out of ideas and think I should just spring for a new Rambo and hope for the best. If anybody has any ideas, I sure would appreciate the help.

One thing you can do to check if the board is damaged is switch the thermistors for the heated bed and the hotend where they plug into the board. The thermistors for these components are similar enough that you will get a reading unless the board is damaged. DO NOT attempt to heat either the hotend or the bed after you have done this because the loop is open and there is no control anymore.

Do you still have the Titan Aero mounted? That Firmware output says SingleExtruder. Not sure if that would cause that error, but they do use different thermistor. Maybe try reflashing with Aerostruder firmware build? I doubt that’s it because I think they both use the same thermistor table, but worth a try.

If you did switch back to the SingleExtruder, double-check that the extruder plug is mated properly (not offset or reversed).

Thanks, rufu5, that’s something I didn’t think to try. Unfortunately it still displayed the MinTemp error, so the board must be shot.

Do you still have the Titan Aero mounted? That Firmware output says SingleExtruder. Not sure if that would cause that error, but they do use different thermistor. Maybe try reflashing with Aerostruder firmware build? I doubt that’s it because I think they both use the same thermistor table, but worth a try.

If you did switch back to the SingleExtruder, double-check that the extruder plug is mated properly (not offset or reversed).
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No, I reinstalled the original Hexagon toolhead and reflashed the firmware. I rechecked the plugs and everything is okay there. I talked with support quite a bit and we went through extensive cable checks and all cables are good and we tested the heater cartridges and thermistors on both the Hexagon and Aero toolheads and they are fine, so the conclusion was it’s a problem on the board. So I ordered a new 1.3 Mini Rambo from them. Hopefully that bring the ol’ Mini back to life. Thanks for everybody’s help.

One last thought… Did you check fuses? One of the 5A fuses (F3?) is responsible for the thermistor outputs (and the hotend fans, I think). That fuse being blown might be consistent having shorted the thermistor wires, and with subsequently getting 0C reading from both thermistor inputs as your MINTEMP error showed.

Thanks, ScottW, the fuses were the first things I checked. They both looked okay, but I checked them with the multimeter to be sure and they were good. I even tried different fuses, but no luck. It even stumped the support guys on this one. I’ve been running the ol’ Mini 15-20 hours a day for over 2 years. Maybe it just wore out. :wink: The new Rambo should be here tomorrow so we’ll see. Thanks again.

Well, the good news is the new Rambo works! :smiley: So it was the Rambo after all. Flashed the firmware with Cura 2.6.63 and it’s working in Cura. Now to get it working with my Pi2 and Octoprint again. Octoprint can’t detect the baud rate for some reason and won’t connect. I’s always something with these robots…

Set the baud rate to 250000 with the new firmware for Cura2 – for some reason, the “Auto” setting on Octoprint doesn’t “auto” that baud rate…

Thanks, that was it! It’s back online and running well. Thanks you all again!