No Start Signal Detected - Forcing Start

My QUB ThreeUp V3 on Windows 7 partially ran for a few days. Using Repetier-Host V 1.5.6, I could manually turn on the extruder and heated bed, but was unable to move any of the stepper motors. The X-Axis stepper motor didn't appear to move at all during test printing (everything else did). I decided to swap stepper controllers on the Ramps 1.4 to see if it was a bad controller. Unfortunately, I did this with the power on and fried the Arduino 2560 and possibly other stuff. The result was if the PS was connected to main power and Arduino/Ramps and then I plugged in the USB in to the computer, the computer completely shutoff immediately. So, I ordered a new Arduino 2560, Ramps 1.4 and stepper controllers and installed all of them. I "believe" I flashed the Arduino using Marlin file from GitHUB. I have no way to know if the Arduino is flashed or not. Repetier Host connects but I am unable to send any commands to the printer (no movement or warming of extruder/bed). When the computer connects there is an instantaneous bump in all of the stepper motors (I assume just a power surge). When RH starts it says: "No Start Signal Detected - Forcing Start." Then after waiting about 30 seconds it says "Communication Timeout - reset send buffer block". It will not do anything else except repeat the Communication Timeout message. Since then I have played around with COM ports, USB cables and even switched to a different computer running Windows 10 with no luck. I set COM40 as the com to avoid conflicts with the other ones.  The Baud Rate is 250000.  At this point I cannot go any further.


  • Host shows connected simply because it connected to a com port available. This does not mean there is communication or communication with right baud rate. In both cases you see behaviour you describe. So you are using wrong com port/baud rate or no firmware i son your arduino or firmware is hanging.
  • Check in windows device manager what com port has been allocated to the arduino when you installed the driver,
    then set the same com port and baud rate in RH
  • Ok, so Arduino went through the verify process without error using the Marlin files from github.  Then it uploaded without error.  Instructions say to set Baud Rate at 250000 in printer settings.  Windows 7 only goes up to 128000 bits per second.  I set both at 115200 but it still has same errors.  Any checks I can do?
  • Ignore what windows says. We are not using that setting. Set the correct baud rate in host, that is all you need to do. Also set transfer protocol to autodetect.
  • Ok, so I figured out what happened.  The new Arduino 2560 I bought was the real one but it was different looking than the one that came with the kit.  So, for some reason the new Arduino 2560 didn't work.  I ordered another Arduino 2560 but found one that looked identical to the original one from the kit.  Bingo, everything uploaded correctly and the unit started working.
Sign In or Register to comment.