Display fades on and off continuously

Hi again,?

I flashed Marlin onto the board without issues. If I plug the board only to the laptop USB, the display comes on normally and allows you to browse through the menu etc.

If I plug the board to the MPCNC (12V P/S), when I turn it on, the display turns on, but it alternates between dim and bright, each time only showing the “Marlin” logo, and keeps doing that over and over.

I have 2 sets of power going to ramps board as suggested. Do I need to power the arduino 2560 underneath it seperately?


Any idea what might be happening?




Check your power supply to see if the light is blinking on and off. Either a bad connection or bad power supply. A Picture of your wiring all powered up will let us have a look and confirm everything is correct.

[attachment file=40951]
Looking at it now, it seems there is not enough power. Multimeter reads 12.5V going into the ramps board. Motors are off. I can’t hear anything coming from the motors. The LED on ramps board keeps flashing green continuously.

The power supply is a 12V 5A/60W


Is this not enough maybe?

That is more than enough. How about that picture?



I posted it above my other post. If you can’t see it I’ll post it again, but I can see it here

12.5v is good but it still sounds like yo have a bad power supply, I see the pic now, the wires seem right but, those are bad power supply symptoms.

OK I’ll see if I can find another P/S to try.

At least now I know the wiring is correct. Wasn’t sure if the arduino also needed to be powered seperately.

Will keep you posted

Thank you


I just blew the board or both the ramps and arduino, not sure.

I have a bench power supply good upto 5A. I just found out there is something wrong with it because it put out possibly upto 45V into the board. I unplugged it and measured with meter and noticed the voltage went upto 45V. The bench supply’s voltage meter wasn’t working. Anyway, plugging it back into USB, there is no flashing green light anymore.

I wonder if both boards are blown or how to find out

45V?!, look for the burnt component.

Nothing looks burnt. lights come on on the mega 2560 but doesn’t show up on the PC when plugged into the USB.

I think it’s all dead. Probably the drivers too I guess

Is it possible that I just burnt the poly fuses on the ramps?

It is possible. Looking at the thread, I think your initial issue may have been a failing 5v regulator. That would explain why they screen is correct when powered via USB, but flakey when powered via the 12v line. I have a RAMPS stack that has the same behavior and has been that way for 2 years. Normally not an issue, as when it is in operation I have both the USB (to a Raspberry Pi) and 12v from the PSU at the same time.

I noticed in some youtube videos the stepper plug has the wires in the order of blue, red, green, black. I have mine red, blue, black, green. Do I need to change it to the first mentioned order or is it fine the way it is? So basically the coil wires are switched on both coils of each stepper.


Nope that just reverses the direction they move.

Thanks Ryan,

So I would just need to invert the direction in Marlin?

Or just flip the plug.


OK I’ll try that when my replacement hardware comes.


I might be wrong about this its a little bit hard to tell… but it seems to me that on the picture the drv8825’s are reversed.

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OMG, you’re right. Thanks Jakob.

John your drivers are in the wrong way, look at my picture vs yours. the little silver pots are supposed to be facing the power plug. Chances are really good those drivers are toast now but flip them and give it a try.