RAMPS help - K40 laser cutter conversion

Projects General Guidance
1

Hello,

I'm attempting to convert my K40 laser cutter to run on Marlin but having an issue with the RAMPS modification.

I've modified my RAMPS board as described here: https://weistekengineering.com/?p=2406

Basically I've replaced both poly fuses with a section of solid copper wire and removed the D1 diode.

Now when I plug the arduino mega into my laptop with the RAMPS board on it's not recognising it's connected. The red leds initially light up like normal but then fade out after a few seconds. The arduino mega board is also getting warm next to the power jack (little black component - not sure what it is?)

If i remove the RAMPS board then the arduino mega is recognised and works like normal so the issue is definitely down to the RAMPS modification.

Any ideas on what's gone wrong?

2

I guess you have created a short between GND and the 5V line, maybe while removing the diode.

3

I don't think i have.

here's a picture of the front and back of the board...

The back isn't the neatest but i don't think there's s short?

Can you see anything untoward?

4

I can not see anything unusual.

Did you try it without the driver modules?

Did that board work before you modified it?

5

Whandall:
I guess you have created a short between GND and the 5V line, maybe while removing the diode.

Hi thanks for looking at my build logs. From my experience you have a short, the little black thing you are referring too is a voltage regulator. It may not seem like it but a short can be so tiny you sometimes can't see it with your eyes alone.

My suggestion would be to apply some good flux and re solder the joints including the diode you removed, also clean the bottom of the ramps board with some isopropyl alcohol and a tooth brush. If you have a multimeeter with continuity testing, test 5v and ground your meter will beep forever while attachrd to those points if there is a short. Don't worry about a short chirp usually the caps are charging.

Let me know what you find.

6

Thank you both for your comments.

I can't remember if I tried it without the drivers or not.

Annoyingly I didn't test it before modifying the RAMPS board :confused:

I shall get my multimeter out and give the board a good clean. It'll have to be next weekend now though.

7

When you remove D1 you are disconnecting the Arduino Vin pin from the RAMPS input supply. This is necessary when the RAMPS stepper drivers are being run above 12V (maximum input for the Arduino voltage regulator). How are you powering the Arduino? On a RepRep 3D printer you would probably be powering the Arduino through USB.

8

johnwasser:
When you remove D1 you are disconnecting the Arduino Vin pin from the RAMPS input supply. This is necessary when the RAMPS stepper drivers are being run above 12V (maximum input for the Arduino voltage regulator). How are you powering the Arduino? On a RepRep 3D printer you would probably be powering the Arduino through USB.

If you look at the setup olive have on my site, on your ramps near the back right corner is a 4 pin white header. This will have 5v in and gnd on it for powering the Arduino. As well you can just power the Arduino through the usb. Don't power it through the power jack.

If powering through the header you must supply a clean 5v this header has no regulation.