Ramps 1.4 shorting Power Supply (also, a Marlin laser engraver)

Ramps 1.4 shorting:
The main issue at hand is a new Ramps 1.4 board I am using will immediately short the LED power supply soon as the power supply is turned on. The first attempt was with motors, end stops, and the Arduino mega plugged in and on with Marlin code. All wiring was identical to my 3D printer, with endstops 2 cable with signal and ground. Since removing the Arduino and unplugging everything else, I have found that it is connecting Pin 3 (5A line) to the power supply that produces the short (Reprap Ramps Diagram, bottom left corner). Does anyone know where I can test with a volt meter to identify where the short is, or if the machine can fully operate without Pin 3's power?

The machine in question:
I am building essentially a Marlin printer (same as folgertech's Reprap), but intending to disable the thermal couples and heated elements, and use a laser diode plugged into D9 in place of the fan using codes M106 and M107. Currently it'll use two Y motors (paralleled and inverted of each other) and an X motor, with endstops for both ends of each motor. I also intend to include two Z motors in the future, and program in either auto leveling or changing the height to follow the depth of cut for multiple layered cuts. The only other necessary connection is D9 for the laser diode.

The laser engraving:
The laser diode being tested is a 500mW 445nm from banggood, which will be replaced with the 2.5mW laser diode or possibly CO2 or other lasers. The laser diode did not come with any circuit (unless its inside the heat sink), but had a wall plug for a simple 5V at 1.15A DC. Due to having several parts on hand, I didn't order the kit and ordered individual required parts. Turns out ordering the laser diode and circuit individually results in not having a power supply for the circuit, so I used my 3D printer's spare. The next issue was the lacking of software features and horrible documentation. I tried 3rd party stuff such as grbl, and got the motors to work, but either the preloaded sketch on the Arduino nano was in relative mode (didn't use end stops without manually sending gcode), or simply wasn't programed to use end stops. Additionally, grbl used M3 and M5, but it was clear the preloaded sketch used some other code to turn on and off the laser. That led me to try and use the spare parts I had for my 3D printer and try using Marlin, since it is slightly familiar, so that I could use the gcode generator of my choice. This has led me to several questions with contradicting answers whose answers probably depend on some small details left out by other articles.

Questions about using Marlin for laser engraving/cutting:
- The only error I encountered prior to the ramps shorting out was the thermal couples (and ideally heated bed and extruder heater) needing to be disabled. Using Repetier only to move the motors resulted in errors. Google results got me that setting #define TEMP_SENSOR_0 6 to 999 would disable the thermal couples, but it errored in compiling and I saw no where in the thermal couple code on how the code would interpret 999 or any other odd results. It appears setting the min temperature to 0 may have worked (no errors in Repetier), but that was just as I encountered the Ramps short. Any suggestions on how to properly disable these via the sketch?
- The Gcode for turning on the fan (D9) allows for power between 0 and 255, but regarding whether a laser diode can operate at any power, I had conflicting answers. I saw a github project for a 40W CO2 laser that I believe controlled its power by pulsing the laser on and off. Other articles suggested laser diodes can be controlled simply by the amount of current passing through them. Meanwhile, other articles said the only way (or easy way they were willing to try) to control their power was with the travel speed. If anyone has knowledge on this matter regarding a laser diode it'd be helpful to know, else the 500mW laser may be getting sacrificed for science.

Thanks in advance.

Did you unplug the driver modules? You may have one plugged in the wrong way round.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The driver modules were plugged in right the first attempt (compared to 3D printer's and read their labels) unless they're simply not true clones are are incompatible. The ramps board is as bare bones as it was delivered with no drivers and only the little connectors connected that are under the drivers to determine the resistance or whatever. The power cables are soldered on due to using the connector being used on the printer, but with 5mm gaps between them and I already used a knife to scrape between them to ensure there was no connection.

Edited 1 time(s). Last edit at 01/27/2017 04:44PM by Gunslinger.

Which way round a driver module goes (i.e. which end the pot is on) depends on the driver. But if you have unplugged the drivers and you still have a short, then perhaps one of the electrolytic capacitors has gone short circuit.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Pin 3 supplies 12 v to the motor drivers,so yes you will need this operate the motors, As DC said, there are 6 100UF capacitors across this 12 supply allso check D2(reverse voltage protection) diode.

The D2 diode is working fine. Still working on reading the capacitors since my multimeter doesn't have a capacitance reading. So far tried setting it to Ohms and charging the capacitor for 10 seconds, then swapping the probes, but the reading immediately drops to 0 Ohms just as fast as connecting the probes together. Getting the same response on the working 3D printer's capacitors, so that doesn't seem to be working as advertised.

If you have a short (0 ohms) between pin 3(+12v) and pin 4 (-v) then you need to un-solder each capacitor or diode to test them

will if any of you have some issues with connecting lasers or need a special PCB for powerful lasers, since you need to do some changes inside electronics when you run 5W+ lasers... they consumes 3-5Amps and 12 volts...

please let me know gfomitchev@gmail.com
or whatsapp, viber +79162254302

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