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remy-s

UMO+. New PCB, bed now only goes down! Help?

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Hi,  some time ago my PCB burned out.

A few days ago I received a new one and connected it to all the components.

Everything on the printer works as it's supposed to except for the Z-axis stepper.

Moving the bed down works as it should but all efforts of moving it up results in it move down but at a much slower rate.

It doesn't matter if I use the controller or the usb cable and cura.

I reinstalled the firmware en restored the printer via the controller multiple times.

so in short: if i try to move it down, the bed moves down in a slow and noisy way. there is no upward motion

Can anybody help me?

Edited by Guest

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Thee first thing to check is the connector for the Z axis motor. Unplug it and examine the pins and leads. Check the pins on the PCB too. There is little risk in doing this.

Next, this is more risky. In the stepper drivers there is a small screw that is a potentiometer that sets the current the driver delivers to the stepper. Do this: power off and unplug the printer, using a small preferably plastic screw driver, very gently turn the screw a very small amount like 1/32th of a revolution. Now put the cooling cover back on, power on and test. If it is not any better repeat. However, if you put a quarter of a turn into it and it doesn't fix the issue it is probably something else. See this information about the direction: http://wiki.ultimaker.com/Electronics_build_guide

Finally and the most risky, to test if the driver is the problem, swap it with another driver. Obviously, do this with the power off. The risky part is two fold. First you need to be sure the pins are aligned and not shifted up or down. *** The second risk is that the driver MUST be oriented correctly *** They must be oriented so that the potentiometer's location matches the driver you are replacing. I believe (but check) the X, Y and Z drivers are all oriented in the same direction so if you remove one of the X or Y drivers to swap with the Z driver, DO NOT rotate them. However, i believe the extruder driver is rotated 180 degrees. So carefully examine the drivers on both sides to understand what I mean.

If the problem follows the driver then the driver is bad. If it doesn't then the board is bad.

Good luck.

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Could this also be caused by a stuck Upper Z switch or shorted circuit for that switch?

 

Hmmm, that is a good thought. I vaguely remember the FW having a bit of a weird behavior if an endstop is triggered by you keep trying to feed in that directions.

It's worth check that too. Check that the Z endstops connectors are in good working order. Then swap them with another axis.

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Next, this is more risky.   In the stepper drivers there is a small screw that is a potentiometer that sets the current the driver delivers to the stepper.   Do this:   power off and unplug the printer, using a small preferably plastic screw driver, very gently turn the screw a very small amount like 1/32th of a revolution.    Now put the cooling cover back on, power on and test.   If it is not any better repeat.   However, if you put a quarter of a turn into it and it doesn't fix the issue it is probably something else.      See this information about the direction: http://wiki.ultimaker.com/Electronics_build_guide

Finally and the most risky, to test if the driver is the problem, swap it with another driver.  

Good luck.

 

Hi, the UMO+ have the same mainboard as an UM2. so it's impossible to swap drivers or calibrate them.

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Obviously the stepper is fine but be aware that what you describe is what happens if one of the 4 wires is cut to the stepper. It will go down but not up. And the noise it makes when it goes down is - well - wrong. And you can easily fight the stepper and keep the bed from moving but if you push it up when you tell it to go up (push hard) it will go up a the correct speed.

But we know that none of the 4 wires are broken - alternatively one of the 4 connections on that connector could be bent/twisted/dirty or the solder on one of those pins could be bad - you could just reheat that solder spot.

Or you can get yet another board.

good luck.

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I can't find anything abnormal on the board, al the solder dots look good and pins in the connector are as they should be. the board itself is brand new as far as I know. the Z-stage just never worked for me with this one. I'm honestly not really comfortable with soldering a brand new and quite expensive board

Edited by Guest

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remy it's time for you to just send it back I think - those photos show perfect looking parts.  I suppose you should have photographed the stepper driver chip also but still.

Or anyway replace the whole PCB for this particular problem printer. Then when it works you can send back the bad PCB.

Edited by Guest

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