Troubleshooting RAMPS 1.4/A4988 Stepper Drivers

My RAMPS 1.4 will not power on continuously from a 12V power supply. I have a real arduino MEGA 2560 for RAMPS 1.4 and an OEM 12V 30A power supply taking in 110V.
The problem is only present when I have 3+ A4988 stepper drivers connected. With each additional stepper driver connected the power supply fan speed increases, making me think that something is wrong with the stepper drivers.

I have adjusted the stepper driver potentiometers Vref voltage down to 0.4V and still have the problem that with 3+ stepper drivers the power supply appears to not be able to power RAMPS. I do not have any heat bed or extruder connected in this instance. In fact, I have the problem when the only things connected are the A4988 stepper drivers.

Without stepper drivers connected, I can connect to RAMPS and measure temperatures using the thermistor and detect endstop status. I can also download firmware without issue.

1. Are my stepper drivers defective or burned out in some way? Is there a way to test for this?

2. Could my RAMPS board be damaged or defective?

I am a bit baffled at this point, as this is the second printer I have built with RAMPS 1.4 and I have done nothing different than last time. Any help or suggestions are greatly appreciated and I would be happy to test anything suggested. Thank you!

Reading your story, it seems you completely disregard the fact that it might aswell be the PSU not functioning well.

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http://www.marinusdebeer.nl/

I don't think it's a PSU issue. I had an ATX PSU (360W) hooked up to it and experienced the same problems, so I thought it was an issue with the PSU initially. So I got this OEM PSU instead.

Additionally, the board doesn't cycle on/off when the stepper drivers are not connected.

If you suspect your RAMPS 1.4 just trade it out with your first machine. If your problem moves with the board you do have a problem with the board.
If your problem stays with the new machine I would suspect motors, wiring or power supply or firmware setup.

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andyinyakima

Open Book, Open Source, You have to Open it to Know what's in it!

I wish I could, but I made that machine for a university that I have since moved from and am now building one at home.

I went through a lot of problems with my RAMPS. Change all the MOSFETS for heaters and fans.
The ones that failed were P55NF06 which I replaced with IRLB8743, but you say that is not your problem.

I had a stepper stick fail also it was the one that drives the two z motors. I called Pololu and talked to a tech.
From that conversation I believe the stepper sticks are only made to drive one motor. They had two devices
that could drive the stepper motors so I opted to purchase the one that could handle 20% more current.
I installed the new stepper stick and the z axis motors seem to run smoother, but the chip was still getting
warm from trying to handle current of both motors constantly. I run Marlin firmware and there is a setting in the configuration.h
where you can shut the power off to the motors in idle. I left drive to x and y alone because they are belt drives and single motors.
I did disable power to z motors in idle and now my stepper stick stays cool.

Make sure you voltage is 12 volt going into your RAMPS. Put a stepper stick into x slot and make sure the motor runs smoothly.
If it checks good check all the other motors using the x plug this will eliminate the motors.

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andyinyakima

Open Book, Open Source, You have to Open it to Know what's in it!

I need to do a follow up on my last post.

When I trouble shoot digital equipment I always keep my problems minimal.
Don't know what drwils01 setup is but mine is a Prusa i3.

I assume that you do shut your power supply when you make changes.
I even shut my connection to my host GUI and sometimes reboot my computer
You may have already checked things out individually.

This video gave me some very good pointers.
[www.youtube.com]

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andyinyakima

Open Book, Open Source, You have to Open it to Know what's in it!