I bought a K8200 printer and when I wanted to calibrate the motor driver it only went to 0.400V. When I tried to adjust it a bit more the mulitmeter jumped to 0.000V. So I calibrated the motor driver to 0.400V but the motors made a very loud noise when I tried to move them. I put some lubricant on the rods to make it move better but it didn’t change anything. Then I read that I could raise the calibration voltage to 0.55V but when I tried to do that I only got 0.000V on all the motor drivers, no matter how much I adjusted it. The multimeter isn’t broken, I’ve tested that already. Could it be that the 4 motor drivers are defect of is the board defect?
Hi Maria,
which power supply are you using? The stock one with 15 V?
You are certain that you did not just loose contact during measurement? Did you use a small enough screw driver? Metal or ceramic blade? If metal: certain there has been no short circuit?
What kind of test exactly did you do when the motors produced that “loud noise”? Turn them manually or send a move-command from the software?
Cheers,
kuraasu
Hi kuraasu,
I used the stock 15V power supply. I did use a metal screwdriver but i did not touch anything else than the trimmer. after the motors made the loud noise i stopped them using the stop motor command and tried to move them in the other direction using the manual controls, when that did not work i tried sending a movement command while turning the motors slighlty with my hands. After that i checked to see if the motor driver were still callibrated correctly but they kept saying 0V everytime i measured them.
Hi Maria,
start debugging from the motor’s side, so you know if they’re ok or the underlying problem. Switch off the board, unplug one motor and test whether it can be moved easily by hand. You should feel a slight feedback from each step, but no real force. Repeat for the other motors.
If this fails (e.g. the motor stalls) it can be mechanical (belt tension, friction in the bearings etc.) or electrical (short circuit between both phases). If you suspect the latter: use your multimeter to check the cables for continuity, connector unplugged of course. The four pins in the connector should behave as follows: (1+2) short, (3+4) short, any other combination open circuit.
Cheers,
kuraasu
Hi Kuraasu,
Thanks for your help. I’ve been able to calibrate the motor drivers but now the Z and X motor won’t work. The Y motor works perfectly. The X motor works but gets stuck all the time and the Z motor doesn’t work at all. I’ve already raised the voltage of the motor drivers to 0.600V. Any idea what the problem there could be? Tomorrow I’m gonna check the wiring to see if everything is connected correctly.
Oh, and the print head doesn’t touch the print bed when it’s put all the way down. Is that normal? Shouldn’t the print head be touching the print bed?
Hi Maria,
sounds like you at least had a first success. But please be careful with the driver’s reference voltage adjustment, as it directly affects the working and holding current used in the motor phase coils (by the way: does anyone know the I/U ratio for those drivers?). Others here in the forum have found that 0.55 V still works and may improve printing results due to larger available forces for movement. But increasing the current will not help you if there are still mechanical problems.
For your case, I’d suggest the following: decrease the voltage to anywhere between 0.475 and 0.55 (i.e. the “usual” range), just to be on the safe side to not burn stalling motors. If Y works well, test the X and Z motors by plugging their connectors into the Y socket. Keep in mind, that it’s the Y end stop which will then stop those axes when you press “Y home”. Test if the Y axis still works if driven by the X or Z axis. You also didn’t mention the extruder motor - is it working, too?
If the first test is not conclusive, you can also pull the small driver boards (“pololus”) from their sockets and exchange them to test whether it is one of them which is malfunctioning (e.g. X pololu onto Y axis, check if Y axis still works well). If motors and pololus all check out mechanical issues would be left, so e.g. for the X axis, release the belt from the motor and check if the carriage is then running freely or if there is any chattering.
Z axis is in principle the same; from my printer I can say that the 10 mm rods on Z axis were under a lot of tension due to tolerance in the plastic parts. If present at your printer, you would have noticed that the rods had to be forced apart to mount the top plastic supports, resulting in a slight outwards bending of the rods (well, ‘slight’ here being 0.1 mm). The preload in the bearings produced by this fault caused them to stall sometimes; more often in the upper and lower range than in the middle, as the preload was of course maximized when the carriage was close to either support.
Ok, finally the (probably) most easy part: the print head should not touch the bed, but be stopped by the endstop shortly above it (0.2 or 0.25 mm according to the manual; use the M3 screw which presses the endstop to adjust). In case you have a very, very flat bed, you can decrease the setting to even lower values, and adjust it so that the actual first layer height of a test print matches the setting in Slic3r. I did that (also on all four corners of the print bed for fine levelling) and got a very small distance between nozzle and bed, I’d say even lower than 0.1 mm. As said, I didn’t measure the distance itself, but rather the print height it produces. When adjusting the M3 screw: one full turn is obviously 0.7 mm, so for small adjustments like 0.05 mm the necessary angle to turn the screw is only a few degrees. Tighten the counter nut enough to ensure the screw won’t move due to vibrations. Oh yes, and while you’re at it: mount the screw head up instead of head down for easier adjustment.
Cheers,
kuraasu
Hi Velleman Support,
After analyse,
- alimentation -> ok,
- 0,4V to 0,6V test -> not ok,
- change step motor driver, extruder turn on Z driver.
Extruder driver is defect or main board, extruder led not flashes.
A use a raspberry pi to command all with octoprint software.
Do you want more information or test ?
How should I proceed for replacement ?
Can I move up your workshop ?
Thank for your help.
First you will have to check if all the little driver boards (the little piggyback boards on top of the mainboard) are working.
I understood you have one axis that is working?
So you know the motor and driver board is working on that axis.
Detach the power and pull out the working driver board. Put the one from the X axis on the Y axis spot and attach the power again. See if you can control the Y axis.
If it works you know you’re driver board for X is working. Do the same for the Z and Extruder driverboards. If the Y motor doesn’t work with a driver board you know that driver board is faulty.
Hello Guy’s
Can some help me with the testing of the volts for stepper motors. Do you have the power supply plug in and turned on when trying to adjust stepper motors
Cheers
The power must be on and you can find the procedure to adjust the reference voltage of the stepper drivers [color=#408000]here[/color] (the procedure is written for the K8400 but you can use the same for the 8200. The only difference is the voltage set to 0.5 - 0.55V)
Thanks for the Help. It’s a much better way to adjust Stepper Motors.