2 RAMPS 1.4 boards, both have a problem

Hi all,

I'm trying to build a Delta Printer i bought from China (the HE3D delta printer). I actually managed to get it to work with my first set of Arduino Mega 2560 and a RAMPS 1.4.

In the beginning I made a mistake by connecting one of the end-switches to the + and - while it is a normally closed switch. So ofcourse it shortned out. On the RAMPS 1.4 board there is no visible damage but on the Arduino the voltage regulator was burnt. This isn't actually such a big problem because the printer will work as long as i have the USB serial cable connected. with this cable connected i made a few prints and it actually worked quite well.

Later i wanted my printer to work properly without the USB cable connected, So I bought a second set of Arduino and a RAMPS 1.4 board just in case the RAMPS did actually take some damage from the short circuit.

Now the new Arduino works perfectly and with the new RAMPS board it works without the USB cable. But to make calibrating easy i still sometimes want to connect it to my computer.

The only problem is that when the RAMPS board is connected on the Arduino my Serial connection doesn't work anymore. programming the arduino will only succeed if the ramps board is disconnected.

so then i tried my first RAMPS board on my new arduino and it has the same problem as with the first Arduino. it only works when the USB cable is connected.

so a short summary:

RAMPS 1 can only work properly if a USB cable is connected to the Arduino, it doesn't matter if I take the fried Arduino or the new one.
RAMPS 2 stops the Serial connection of the Arduino. if the RAMPS board is disconnected the USB serial connection with the Arduino works again.

Has anyone have any experience with those problems or any idea to solve at least one of them?

For those who need to know :
HE3D Delta Printer
Arduino Mega 2560 Clone (CH340 USB to Serial chip) + RAMPS 1.4
RepRap Smart Controller
Dual Extruder & Heated bed
Repetier host 1.6.2 and Repetier Firmware 0.92.9
Windows 10

Thanks in advance!

Edited 1 time(s). Last edit at 01/16/2017 10:08AM by Morph1.

In my opinion you should never upload the firmware to the Arduino with the Ramps connected. I always disconnect my Arduino before I connect it to my laptop to update the firmware. The Arduino just seems to not respond well to being programmed while all of it's pins' are connected. I'm not sure why or if it's absolutely necessary but that is what I have noticed in my experience. I also disconnect the USB before I plug the Ramps back in. And I always plug the USB in before connecting power. Again, not sure if it is absolutely necessary but that is the process I follow and it has seemed to work just fine. There are commands you can send in Repetier to change some settings while in operation which might be worth looking into if you are looking for a more convienient way to tune your set up.

When you try to connect USB to arduino with the RAMPS 12V power supply ON, make sure Computer and printer-PSU use the same mains circuit ( wall socket ) otherwise you can get "ground loop" issues that can damage the PC or printer.
The USB cable can get very hot and melt, too.

Thanks for your reactions,

With a little searching i found a topic on this forum which said that some RAMPS boards have te problem that the 12V power input on the ramps board is somehow directly connected to the RX pin of the arduino. So that's why I couldn't program my arduino with the RAMPS board connected. Before i fixed that problem I already fried my new arduino and even the USB Ports on my laptop...

Seems like I will be printing again with both usb cable and power supply connected for a while...

Anyway Thanks!

HI,

Can you help me by tell me how to fix the problem of 12V in rx pin of RAMPS?, I have exactly that same problem.

Thank you so much