Driver board problem

Hey guys, I flashed my Mega with Marlin and tweaked the driver voltage as low as I could…about .920…

I only have the motors, extruder and extruder fan hooked up…no heated bed and no end stops. When I try to manually jog, nothing happens… I’m thinking that I should get something, even something wrong (reverse movement etc) but I’m not getting any response from the machine.

Repetier host connects but any commands time out…

Any ideas? All help greatly appreciated…


What drivers? 0.92V is really high for the usual ones.


What do you have, where did you get it, what firmware, what board? Lots and lots of details please. At this point I can’t even make a guess. Pictures, links anything.

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Hey Ryan, thanks for responding…

The Arduino board is a Mega clone off eBay, as is the RAMPS 1.4…the DRV8825 drivers I ordered from your shop. I flashed the Mega with the RAMPS version of Marlin that I got from here. Once the driver voltage gets down just below .920 the voltage jumps back up to about 2.5 ( both these numbers vary from driver to driver by a 10th or so)

The hot end is a Bowden clone, again from eBay. The extruder motor is a 37 oz in from Stepper online, the other 4 are Minebea 76 oz in. I don’t have anything else hooked up, no heated bed and no end stops.

Repetier connects but any command sent to the board times out with no response from the machine.



Extruder motor:

Hot end:



If there’s anything else I can provide, please let me know…

That is not right, something is broken, are you sure they are in the correct direction? 0.9V is too much for most single steppers. 12V, 24V?


Mac or PC? Buadrate, port?

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I’m running 12v and the drivers are oriented with the pot away from the power input connection.

I’m using a laptop with Windows 7, 32bit…baudrate is 250000 and port is set to Auto.


That is backwards, I am not sure if that kills the drivers or not.

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Must have killed’em… turned them around and can’t adjust below about 1.5v. I replaced two with spares that I had and they seem to have more adjustment range…where should the voltage be set?


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Looks like I’ll be making another driver order from you…

Sure wish I had found you guys before I began this journey…

Still seem to have a problem…after removing the old drivers and installing and adjusting the the two new ones, I still get no response from the two axis that have the new drivers.

Is the firmware set up for end stops? And if so, would my not having any be causing the problem?

What firmware did you flash? Even if it, is a firmware with endstops you can always move in the positive direction.

Try not setting the com port to auto, Make sure it connects. Issue an “M119” command and see what gets returned. I don’t think you are connected, or you didn’t actually flash the board.

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It lives!.. changing the port did the trick. When I first sent M119 it did the same as always and timed out… after changing the port, it reported the status of the end stops as open.

Thanks Ryan!

Below is a picture the beast…

Oh, don’t be too harsh… I intend on tidying up before I actually try to print…lol

Almost forgot, I intend to install end stops…should they limit + travel or - travel?


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As far as I understand, Endstops are not really required to limit the machine movement to a save range but to enable the machine to find the “home” position after a power cycle.

Usually the z is limited in the lowest position, you can set this to match the height of your bed.

x and y doesn’t really matter what I have seen from reprap machines they have x and y at most negtive position as well. The setting in the firmware have to match the direction of the steppers and the location at the machine.



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Once I got the new drivers installed and adjusted, everything seems to be working fine. So now I ad the end stops…and they have no affect. They’re positioned to stop the hot end at the front left corner of the work area with it just touching the surface. Is there something I need to tweak?

The other “major” issue that I haven’t been able to figure out is, that when I try to print, the hot end rises to 35mm above the work surface, moves to position and starts printing without lowering back close to the surface.

Any help greatly appreciated, Rick

Do you have them wired Normally open or normally closed? What does m119 say when you are physically holding one closed?

Lots of details will help.

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My apologies for not knowing what details to provide, I’m still too new at this to even know some of them exist…lol

They are wired NC…and m119 returns “triggered” on all three axis with none of them activated and each one returns “open” while respectively activated.

Sounds like you are running the wrong firmware image. NC end stops shouldn’t be triggered until they break the connection, but the firmware (or firmware configuration) determines whether they are expected to be NO or NC, yours expect NO which is non-standard for the MP3DP firmware.

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Thanks Bill, you were correct in your thinking…I had inadvertently uploaded an incorrect version of the firmware. But after correcting that with the version for the MP3DP, I’m still having major issues.

Even though my end stops now show correct response to m119, the machine is still ignoring the end stops as well as trying to print before the head is at temp and moving the wrong direction when under manual control…or moving the wrong axis.

Maybe a bad RAMPS board?..bad MEGA clone?