Ramps 1.4 testing without Extruder or Heated bed connected

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GeneTimothy
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Joined: Mon Apr 16, 2018 8:24 pm

Ramps 1.4 testing without Extruder or Heated bed connected

Post by GeneTimothy » Mon Apr 16, 2018 8:59 pm

Hello everyone -

I am new to this forum after watching Tom's Dolly Clone and deciding to try my hand at building a 3D printer from scratch.

I have the Ramps 1.4, stepper drivers, LCD and 12volt 20amp power supply connected, and have been testing the endstops for the past few days making changes to the marlin Firmware trying to get the correct direction movements, etc.

I have not hooked up anything as far as the extruder and the heated bed. Everything has been working with no issues, the steppers move fine using the Printerrun software. i was just having issue trying to get the homing setup.

last night while testing I saw on the internet that I might have the endstop wires plugged in the wrong way. So I changed them around as I saw on the post on the internet and plugged the power in. I immediately saw the famous white smoke coming from between the arduino and ramps board, so I unplugged the power as fast as possible.

My question is this.... was I supposed to have the heatbead and extruder plugged in to test the just the stepper? is there a setting I was supposed to turn off in the firmware while just testing the endstops and stepper movement.

I am assuming that the Mosfet is now burnt out. ( see attached photos )
opposite_MOSFET.jpg
Notice discoloration and start of bubbling of the board
opposite_MOSFET.jpg (202.44 KiB) Viewed 121 times
There is no noticable damage other than the discoloration of the backside of the board where the MOSFET is soldered, you can see in the other photo that there is no noticeable damage to the MOSFET itself.
MOSFET_side.jpg
Notice no apparent damage to the MOSFET on this side
MOSFET_side.jpg (108.18 KiB) Viewed 121 times
I guess am going to have to replace the Mosfet or buy a new ramps board. or start suing an external Mosfet board. is there a way to test the circuit to see if it is indeed burnt out?

Any of you more experienced users have any tips for me?

Thanks in advance for any help you may provide and please excuse my ignorance!!

Stefan
Posts: 92
Joined: Thu Jun 15, 2017 12:46 am

Re: Ramps 1.4 testing without Extruder or Heated bed connected

Post by Stefan » Mon Apr 16, 2018 11:10 pm

Hi GT,

Welcome to the forum, and congrats on your Dolly.

The mosfet you are indicating is the one for the bed. It carries the highest current on the board (10-11 amps). You MAY have not blown it out. I'm not sure how you would have managed to short it from the endstop pins, but who knows. Don't swap wires (or adjust drivers) while the power is on; it's a big hassle, but saves you a lot of trouble. Also, clean off the goop from underneath the board. You want to make absolutely sure that no solder spatter is shorting leads.

You should have no problems testing the steppers independently of the other circuits. Unless you turn on the bed from the firmware, it SHOULD be fine. Grab your multimeter (you have one, right?) and connect it to the D8 ports. In Pronterface, set you bed temp to something higher than room temp. If the voltage goes to 12, you are probably ok.

-Stefan

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GeneTimothy
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Re: Ramps 1.4 testing without Extruder or Heated bed connected

Post by GeneTimothy » Tue Apr 17, 2018 12:17 am

OK thanks -

I changed the endstop wiring while the POWER was OFF.

I will give your suggestions a try and see what I find.

Thanks for the reply and the info!!

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GeneTimothy
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Re: Ramps 1.4 testing without Extruder or Heated bed connected

Post by GeneTimothy » Mon May 07, 2018 12:52 am

I tested the D8 and the voltage seems to be OK, so I am thinking that the MOSFET has not burnt out...however now the LCD will not give a display UNLESS I have the USB plugged in from the PC.

I have the power hooked up from the 12 volt power supply and the ramps board has the D1 soldered from the factory. I have done some research and other folks say that the problem is a blown voltage regulator on the Arduino.... resulting from reversing the endstop when plugged in. However I tested the Voltage regulator on the Arduino with a meter and it gives 5.04 volts, which seems to be OK....

Am I missing anything obvious? Anything else I can test to see why the LCD won't work without the USB connected?

I am not opposed to having to use the PC to print at this point, until I learn enough. Will it do more damage if I do so?

Thanks in advance for any help!!

Stefan
Posts: 92
Joined: Thu Jun 15, 2017 12:46 am

Re: Ramps 1.4 testing without Extruder or Heated bed connected

Post by Stefan » Tue May 15, 2018 6:05 am

I always print with my USB connected, so I don't imagine that will hurt.

There are two power connections into the ramps: one is just for the heated bed and the other is for everything else. Note: I have seen ramps with just one set, too. I wonder if you blew a polyfuse?

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