I have been printing successfully for a couple of months now. every once in a while the print will stop or I cannot connect. but now It is constant. I can get it to connect sometimes for a minute or two then it will loose the connection. I have not made any changes to my environment , I am printing from a laptop through a powered USB hub to the printer. here are the logs below I keep getting this error before I lose connection echo:Unknown command: "" I have reinstalled the USB driver and have rebooted several times. it almost seems like something is wrong with the printer circuit board. thanks for any help John 20:32:26.102 : echo: External Reset 20:32:26.102 : Marlin 1.0.0 20:32:26.102 : echo: Last Updated: Jul 22 2013 15:56:56 | Author: (none, default config) 20:32:26.102 : Compiled: Jul 22 2013 20:32:26.102 : echo: Free Memory: 5522 PlannerBufferBytes: 1232 20:32:26.367 : Error:0 20:32:26.367 : : Extruder switched off. MINTEMP triggered ! 20:32:26.367 : Errorrinter stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting) 20:32:26.601 : echo:Unknown command: "" 20:32:27.319 : FIRMWARE_NAME:Marlin V1; Sprinter/grbl mashup for gen6 FIRMWARE_URL:http://www.mendel-parts.com PROTOCOL_VERSION:1.0 MACHINE_TYPE:Mendel EXTRUDER_COUNT:1 20:32:30.018 : FIRMWARE_NAME:Marlin V1; Sprinter/grbl mashup for gen6 FIRMWARE_URL:http://www.mendel-parts.com PROTOCOL_VERSION:1.0 MACHINE_TYPE:Mendel EXTRUDER_COUNT:1 20:32:31.188 : Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting) It starts off with a temp and then when it looses connection the temp is reset to 0 degrees. then it will not reconnect. i can send the M999 command and it will raise the extruder .But I cannot manually move the extruder up/down left right etc. I would think that the system would still allow you to move the extruder even if the heater is off. when it was showing a temp I moved the wires around quite a bite and I could not make it short. I have to reboot the PC and the printer several times to get it back. i am going to try another PC next. Just tried a different PC and USB cable. same result. must be something on the Robo. I cannot get the Robo to respond except for the M999 command. the temp says 0 degrees. any ideas ? bad circuit board? open circuit ? any ways to test ???