Anycubic Mega S & Chiron randomly stops printing. Troubleshooting tips.

3D Printers, Hardware, Tech Support

I’ve created a list of list of possible issues that can cause the Anycubic MEGA S and Chiron to randomly stop during printing.

  • Loose connectors
  • Bad thermistors
  • Corrupted SD card file system
  • Failing SD card reader board
  • Broken wiring

Anycubic print stoppage error message

Symptoms often include:
  • A random (heartbreaking) print fail.
  • Your printer will sound it’s power up chime. (Then you sing a four letter aria that would make Pavarotti proud.)
  • When attempting to manually move the print head or build plate you get an error message, “The Machine is running, please try again later.”
  • An inevitable power cycle to regain gantry control to unbury the print head from the 90% completed garden gnome sized baby yoda you were printing for your grandma.
  • General disgust.
Loose Connectors:

You’ll notice most of the connectors on your Anycubic printer have blobs of hot glue on them.. this struck me as odd until I watched this YouTube video about similar random print fails. The hot glue acts as a lock minimizing the chance of connector back out.  I was really surprised to see the temp sensor for the heated bed glued to the mother board. If you’ve purchased your Chiron recently, you’ll also see the hot end data/power cable is cinched to the cage using a zip tie locking it in place.

Loose connector resolution:

Pretty straight forward.  You simply go connector to connector checking to see if they’re seated and tight. If you’re feeling frisky you can add reinforcing hot glue.

Bad thermistors:

Thermistors are used in the hot bed and heater block as part of the feedback loop that keeps the printer on task.  If the thermistor fails, gives bad data, or gets disconnected the print head will halt immediately and the hot end cooling fan will kick on full speed. I think it does that so it can’t hear me cussing. “T0 sensor abnormal”

Hot bed thermistor Resolution:

To test if your hot bed thermistor is causing problems, you can turn off the heated bed in your slicer and run a few test prints.  If the intermittent fail goes away, you’ve got your culprit (and hopefully a bunch of double sided tape). In the case of my Mega S, my print would fail at 3 hrs out (randomly), then 1 hour, then during the skirt print,  then it just wouldn’t start. Anycubic customer support recommended turning off the hot bed and sure enough it printed to completion. Anycubic will work with you to get the bed replaced or you can learn more about replacing the hotbed thermistor here: https://youtu.be/UEfxie6aVtw

Heater block thermistor resolution:

The easiest solution is to install the spare hot end that came with your Anycubic.

Heater thermistor combos are not that expensive if you’re comfortable splicing wiring. 24V 100KΩ NTC3950 Thermistor & Ceramic Cartridge Heater 12V 40W.  Consider using thermal paste when installing your thermistor and ceramic heater cartridge.

anycubic V5 hotend

Corrupted SD card file system:

The file system on your SD card has become corrupt or you have a memory failure going on.

Corrupted SD card file system resolution:

Reformat your SD card using fat32 for the file system or try a new SD Card.

Failing SD card reader board:

So it’s possible (rare) the SD card reader daughter board is acting up and causing intermittent failures.

Failing SD card reader board resolution:

Remove the SD card from your printer and plug a USB cable from your Anycubic to your PC to run the print directly from your slicer. (At the time of this writing I was  literally 15min from completion on a 7hr Cura/PC to Chiron test print (1 of 3) to determine if my SD card reader is flaking out. Just one of the reasons I decided to make this list.)

Broken wiring:

Chiron heated bed cable breakIn my experience broken wiring normally affects the hot bed where the power and thermistor wiring come off the bed and begin running down the Chiron frame. They really need a cable plug assembly mounted to the bed that reduces stress on this cable and allows you to simply unplug the connector from the bed to replace or service it.  You could build it into the bed clamp assembly for added strength.

Broken wiring resolution:

Shoot a pic to Anycubic customer support and they’ll work with you on getting it replaced. OR if your handy with a soldering iron and heat shrink tubing, the fix is straight forward.