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A5 randomly crashes with the message "closing mashine ...."


my A5 randomly crashes with the message "closing mashine ....". It hapens when i print direct with the USB Stick OR when i print with Cura from the computer. Sometimes everything is fine and sometimes it crashes in the middle or during the print. It has nothing to do with the files i am printing. I am printing the same file an sometimes it works and sometimes not.
I also happend when i change the filament. After ejecting the filament i got tis message. No always but sometimes.

i am using now the firmware 1.19c und the LCD Firmware 3.03. But i had the problem also with stock firmware.

I found nothing in this forum and Google also has no answers? :#


  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    edited March 6
    Welcome @hanzfranz !

    Sounds frustrating :disappointed: I've never seen that message before though! I'm convinced the MKS tft28 lcd module has poor quality control from MakerBase. So many seem to be flakey/unreliable garbage :tired_face: ... and it causes so many problems - it is the Achilles heel in some A5. I would bet that yours is faulty...

    I suggest unplug the LCD module from the motherboard, and then try print from USB cable via PC, and see if the problems keep happening.

    Post edited by Samuel Pinches on
  • hanzfranzhanzfranz Member Posts: 9
    Hi Samuel,

    thanks for your quick answer. Perhaps i have bad luck with my A5. I got my printer with a brocken X motor. After changing the x motor i am happy with the prints with PLA.

    I am not able to print ABS. All my attempts failed because the ABS does not want to stick to the bed. The maximum temperature i get with the bed is 104 degree!! Any idea?

    i found this MKS tft28 on german amazon store:ÅMÅŽÕÑ&keywords=MKS+tft28&qid=1551942121&s=gateway&sr=8-1

    Is this the right one?

    Thanks also to all your excellent videos on youtube. They helped me a lot!!!!!

    I also get this message during nearly every print with cura and printing via PC. The print continues with no error.

  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    When gcode is sent from the LCD to the motherboard, or from the computer to the motherboard, it has a mathematically calculated number added to the end of each line as a check to make sure the line wasn't corrupted. This number is a checksum, and it is always the same number for a specific line of text. When the motherboard receives a line, it calculates the checksum number too, and then compares it to the checksum number that was sent. If there is an error, you will get this message.

    Typically, this indicates a communication problem between the device sending the gcode and the motherboard. I am very confused why this message would be occurring on the LCD when printing from the computer? Do you see this error message in the pronterface log as well?

  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    edited March 7
    If you are printing from a USB drive, then I would not be surprised by this error, because the MKS LCD module is prone to making errors. I researched this problem, and in one case I found the MKS LCD was reading a USB stick incorrectly, while printing from SD card was working fine.

    I really don't like the MKS LCD module.... I wonder if in this case, the MKS is hearing the gcode from the computer, but it is being corrupted between the motherboard and the LCD... so that the LCD module is detecting these errors. It might be worth trying to shield the LCD cable between the printer and the LCD with foil tape, similar to what I did recently to the A1 printer screen cable.

    Post edited by Samuel Pinches on
  • Der_MuckDer_Muck 🌟 Super Member 🌟 Posts: 238
    Some ABS filaments stick better and some less to the black diamond plate.
    Try cleaning it very well with spiritus and use a 10-15mm skirt on your prints. Also the first layer high has to be 100% correct.    I printed ABS with the standard JG A5 hardware setup well so its passible.
  • Enrique RiriEnrique Riri 🌟 Super Member 🌟 Posts: 36
    edited March 8
    I agree the fact to shield the LCD cable. I made that too. Also the length of the cable is too long. that can increase interference and noise capture too. Another thing to take care: Shield of the USB connector. On last A5, you have a plastic Isolator to avoid hazardous CC between usb metallic sticks and case shield who is directly connected to 220v earth . A5 have serious concept issues. You can easely distroy the mother board, if you have insulation issue with your extruder temp probe too. (screew and small metal pièce). this happens often, when you replace the nozzle and you Don't take care. By the way, going back to your actual issue, take a look on the 2 USB connectors on the right and insulation with the chassis and check when you plug PC computer cable or USB stick, you don't create hazardous contact  between shield of the USB and chassis.

    For info, logic GND and and 220v GND are not the same and you have booth in the printer. Jgaurora took to much risks and in some points we can create an Shortcut between them and cause dammage on the logic boards.

    Personnally I had similar issues on the past and the solution was: LCD replacement and I only print with USB sticks without metalic shield (same stick as delivery with the printer). I also replaced the heating nozzle with that (more accurate temp sensor probe) :
    Thanked by 1Samuel Pinches
    Post edited by Enrique Riri on
  • Der_MuckDer_Muck 🌟 Super Member 🌟 Posts: 238
    I thought it would be only a problem with the unearthed printers, the old once dont have a case earth extra, they are simply earthed with the MW power sup. case and that dont work well because the JGs case is isolating to much.
    As i saw, the isolator of the USB port does nothing than set the USB port little back. I dont understand that solution because the USB port itself is plastic and is allready isolated. So why another plastic isolation when the USB port is plastic to.... The older JGs should have some V on the case, the newer should not have that problem. I thought that was the problem because over the V on the ground you short to the USB ground.
  • hanzfranzhanzfranz Member Posts: 9
    edited March 15
    Thanks for all the answers!!
    When i print via PC und remove the LCD cable before printing, i don´t have any problems!! That tipp worked very well. Would pasting over aluminum foil to the LCD cable maybe work to?

    I got the "closing mashine ..." message nearly every time when i push out (change) the filament with pluged  in LCD cable!!

    Is there a way to change filament with cura or other programs because i don´´t wont to plugin the lcd cable every time i have to change filament.


    By the way. I shield the LCD cable but without success. The cable is unnecessarily too long!!     

    I think i have to buy a new LCD Board.

    Post edited by Samuel Pinches on
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    edited March 15
    @hanzfranz I think it is worth a shot - if you don't have aluminum tape, you could try aluminum foil, and then put regular tape on top to insulate. It would be bad if the aluminum foil contacts the other components on the board.

    Rather than replace the LCD, you may find it worth investing in a raspberry pi 3B+ for running octoprint
    Post edited by Samuel Pinches on
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    I split this conversation into two topics, the second half is here:

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