min/max temp error

Hi there!

Problem:
I get the error Min Temp, and when I then switch off and on again (after 15 sec) I get the error max temp.

So… Background…

I just set my new TAZ 4 up on thursday, so I’m very much the noob at this, but committed to getting to pro… :slight_smile:

I’m afraid I might have broken something but I’m not sure how to find out, soi I’d appreciate some help…

I got a clogged nozzle and a lot of oozing along the threads, out over the heater element (read up on it) and after trying to remove as much as possible by “fishing” with a strip of metal wiring I ended up realising that I’d have to remove the nozzle.

I didn’t realise I had to turn the machine off for removing the nozzle, since I used the display to make sure I was at the recommended 160 degrees, which might have been my big mistake (read in another thread that this was a good way to short the circuit board).

My heater element was really loose, which led to it moving a lot when I removed the nozzle (wiggling say ± 15 degrees). After I cleaned the nozzle out and replaced it, tightening the element’s three screws at the same time, as soon as I turn the heater on, I get the error Min Temp, and when I then switch off for 15 sec and on again the max temp error shows up and the extruder switches off…

How do I run a diagnostics on this to find the problem?

I’ve checked the wiring, and it’s not broken anywhere that I can see… The green inset (heater element?) is loose though, so I can actually move it back and forth a little bit…

Any help appreciated!

Here’s the readouts from Printer Interface when I started it up…

Connecting…
start
Printer is now online.
echo: External Reset
Marlin 1.0.0
echo: Last Updated: Nov 5 2014 14:09:59 | Author: (Aleph Objects, Inc, TAZ config)
Compiled: Nov 5 2014
echo: Free Memory: 3114 PlannerBufferBytes: 1296
echo:Hardcoded Default Settings Loaded
echo:SD init fail
Setting hotend temperature to 235.000000 degrees Celsius.
Setting bed temperature to 85.000000 degrees Celsius.
Print Started at: 15:46:04
Paused.
Error:0
: Extruder switched off. MAXTEMP triggered !
Error:Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
Reset.
echo:Hardcoded Default Settings Loaded

echo:PowerUp
Marlin 1.0.0
echo: Last Updated: Nov 5 2014 14:09:59 | Author: (Aleph Objects, Inc, TAZ config)
Compiled: Nov 5 2014
echo: Free Memory: 3114 PlannerBufferBytes: 1296
echo:Hardcoded Default Settings Loaded
Error:0
: Extruder switched off. MINTEMP triggered !
Error:Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
echo:SD init fail
Disconnected.
Reset.
Connecting…
start
Printer is now online.
echo: External Reset
Marlin 1.0.0
echo: Last Updated: Nov 5 2014 14:09:59 | Author: (Aleph Objects, Inc, TAZ config)
Compiled: Nov 5 2014
echo: Free Memory: 3114 PlannerBufferBytes: 1296
echo:Hardcoded Default Settings Loaded
echo:SD init fail
Error:0
: Extruder switched off. MINTEMP triggered !
Error:Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)

echo:PowerUp
External Reset
Marlin 1.0.0
echo: Last Updated: Nov 5 2014 14:09:59 | Author: (Aleph Objects, Inc, TAZ config)
Compiled: Nov 5 2014
echo: Free Memory: 3114 PlannerBufferBytes: 1296
echo:Hardcoded Default Settings Loaded
Error:0
: Extruder switched off. MAXTEMP triggered !
Error:Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
echo:SD init fail
echo:Hardcoded Default Settings Loaded

echo:PowerUp
External Reset
Marlin 1.0.0
echo: Last Updated: Nov 5 2014 14:09:59 | Author: (Aleph Objects, Inc, TAZ config)
Compiled: Nov 5 2014
echo: Free Memory: 3114 PlannerBufferBytes: 1296
echo:Hardcoded Default Settings Loaded
Error:0
: Extruder switched off. MAXTEMP triggered !
Error:Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
echo:SD init fail

Update:

No breaks on the cables, although there is a chance the thermistor ptfe tubing might be damaged at one place although I don’t know if it has touched the heater block or not. 5.7Volt over the thermistor and 100kOhm.

When I turn on the printer, it says TAZ Ready and shows correct temperatures. When I heat the bed, everything works fine. When I heat the hotend, it goes to about 40C and then it turns off saying Err: Mintemp and then the temperature jumps around a bit, and finally it stopped on 20C, although when I touch it, it’s closer to 50 (hot but not scalding).

Thermistor shot or something on the Rambo board?

Any suggestions?

Anytime you have a MIN TEMP error the RAMBo electronics has lost the thermistor reading. That’s typically due to a connection issue: (connector pin that’s not fully seated within the connector, wiring break, loose connector on the electronics enclosure. Power down the printer, and unplug from any USB connection and from the power supply. Then reseat everything.

You mentioned a break in the PTFE tubing- a picture of that would be great.

After it’s confirmed that the PTFE insulation is fine, you can then move the wiring around (wiggle it, just a little bit (sorry…)) to see if you can cause the error to appear again.

Ok. The error returns every time I try to heat up the hot end. The printer has been standing still for the last three days which is very frustrating… I assume the board hasn’t been shot yet if it shows the bed temperature fine? And it heats the bed properly… I read at the seemecnc forum that there is a common control circuit for all thermistor connectors on the board, so if that was shot, all thermistor reading should be out the window, right?

I’ve played around with the thermistor seating and the tubing quite a lot, and there is no difference in symptom. I’ll try and get a good picture of the ptfe tubing, but I am sure it’s not touching the heater block…

Would it make a difference to replace the thermistor? Or is it ok? I’m pretty handy with mechanical things but electronics were never my thing… :slight_smile:

As you can see, there is some damage to the tubing, but it’s also clear that it’s still insulating the wire from the block…

I filmed a video as well when I start it, all is fine, then I heat the bed, all is fine. Then I start the hot end, which heats to 30 something, then comes the error mintemp and then it jumps down to 14C…

So, replace the thermistor and tubing?


Thanks for the pictures- a thermistor may be exactly what you need. When you held onto the heater block with a tool the thermistor insulation and potentially the thermistor itself could have been damaged. Send your information into Support@LulzBot.com and we’ll see what we can do- send in your:

  • Order number

  • 3D printer serial number

  • Contact information

  • Shipping information

Thanks!

Thanks for your feedback, Orias! I really appreciate it.

I finally spoke to Support yesterday and they are helping me out with a new hot end!

Big kudos to the Lulzbot team for the exceptional service.

// A much happier Homer

Well, to finish off this thread properly, here’s a picture of the culprit…

I dont necessarily see something super wrong with that picture, can you describe your problem? Last night my hot end just cooled down in the middle of a print, I caught it before it made too much of a mess (clog, etc.). But now my hot end wont heat up anymore and I get Err: MIN TEMP on my LCD display when i want to heat up the hot end.

I guess I will be contacting support :frowning: I hope I dont need a new hot end :frowning:

Anytime you have a Min Temp error it’s hot end thermistor related. Start there, check for continuity and resistance and trace back until you find the break/connection

But now my hot end wont heat up anymore and I get Err: MIN TEMP on my LCD display when i want to heat up the hot end.

Unplug your thermistor/heater cartridge harness. Get an ohm meter and check what the thermistor reads. It should be around 100kΩ at room temp. If your meter displays “ol” or whatever the screen looks like when your leads are not connected to anything then your thermistor is blown. If it reads a really low resistance–say <50Ω–then the thermistor wiring is shorting on the heater block. Hope this helps.

Indeed it was my heat temp resistor! Replaced and back up and running thanks to Lulzbot support.