Hello all,
I am having a problem with my K8400. No matter which position I turn the pots on the stepper drivers to, they overheat and are unable to drive the motors. I have tried a print with nearly every current adjustment possible, yet each time the drivers reach an extremely high temperature and cease to function. This happens somewhere between homing and printing the first skirt lines. Between each attempt, I let the drivers cool to room temperature.
From the research I have done, some drivers are turned counterclockwise to reduce current, others clockwise. I have tried both positions with similar overheating on every driver.
Thanks for any help you can give me.
Hi,
First you need to adjust the drivers to the recommended reference voltage (check the procedure in the Wiki).
Then check the correct alignment of the axis, tension of the belts etc (have also a look in the Wiki).
If the drivers are overheating if probably means the current drawn by the motors is too high and this happens when they’re struggling to move the axis.
And it can do no harm to glue heat sinks on the driver chips.
Electronically, I am pretty hopeless but have adjusted stepper drivers on previous printers. Usually I just have the printer run back and forth while I adjust the pots. These drivers overheat before I can find the “sweet spot,” and at this point I am not sure if a working position exists. I added heatsinks as soon as I discovered the problem.
Mechanically, I am almost positive that the axes, belts, pulleys, etc. are all aligned perfectly. I used some tools I made to ensure that everything is square, and I greased all of the threaded and smooth rods on the printer. Moving axes by hand is smooth and easy.
Thanks for your reply.
[quote=“spaceorange12”] I am not sure if a working position exists[/quote]Adjust them to 0.9V like described in the manual. It works for almost everyone. If the voltage is too low or too high they can overheat indeed.
[quote=“spaceorange12”]I used some tools I made to ensure that everything is square,[/quote]Read the Wiki anyway because in the beginning I was convinced I had it right too.
I read the wiki and found some conflicting instructions on how to measure the voltage. The one I am most confident in is using alligator clips to connect the screwdriver to both the potentiometer and the (+) multimeter, and connecting the (-) power terminal to the (-) multimeter. Is this a procedure you would recommend?
If all else fails I have some spare Pololu drivers that are perfectly set, are they compatible with the K8400?
Using the printed tools to align the axes and making sure the rods were the correct distance apart was recommended by the wiki.
I assume that when you refer to the wiki you are referring to the “k8xxx” page that is understandably blocked on school wifi.
I just tried the testing configuration I mentioned, but got zero volt readings every time. The X and Z drivers work, but when I touched them I burned my fingers. The Y driver stays cool but will not move the motor.
Some guesses:
- Mainboard broken
- This is likely because I believe I shorted it when adjusting
- Also possible that it killed the Pololu drivers I tried
- Drivers broken
- Possible because I have never seen a driver reach such a high temperature
- Somewhat unlikely because the originally functional Pololus wouldn’t work
- Mechanical troubles
- Very unlikely because I can tilt the machine and the axes will slide
- Alignment tools and guidelines from both the wiki and the manual were used
If anyone has other ideas I’d be glad to hear them
[quote=“spaceorange12”] The one I am most confident in is using alligator clips to connect the screwdriver to both the potentiometer and the (+) multimeter, and connecting the (-) power terminal to the (-) multimeter. Is this a procedure you would recommend?[/quote]That’s the one recommended in the Wiki and that you should use (and the only one working with Pololu drivers). The first picture is the one from the Velleman manual. [quote=“spaceorange12”]If all else fails I have some spare Pololu drivers that are perfectly set, are they compatible with the K8400?[/quote]If these are DRV8825 : yes.[quote=“spaceorange12”]I assume that when you refer to the wiki you are referring to the “k8xxx” page that is understandably blocked on school wifi.[/quote]That’s the one. First time I’m hearing it’s blocked.
[quote=“spaceorange12”]The Y driver stays cool but will not move the motor.[/quote]Must be dead. Swap it with a working one and check if the axis is working.
[quote=“spaceorange12”] I touched them I burned my fingers.[/quote]Are they heating even when the printer is idle? They can reach 100 when in use… but usually the temperature stays below 70°. There’s a fail-safe cutting the power to the motors if the temperature is too high. So it shouldn’t kill them.
[quote=“spaceorange12”]- Mainboard broken[/quote]Hard to tell from here…
As I mentioned this gave me zero volt readings on every motor, not sure why.
I just tried them, as with the stock ones they failed to drive the motors. However, they did not overheat.
“xxx”
I tried with the DRV8825s I talked about earlier, same problem.
They stay cool until I attempt to move the motors. I guess the fail-safe is faulty because they were well over 100˚ even with the heatsink.
I contacted the USA support group, perhaps they will inspect it for me.
[quote]I contacted the USA support group, perhaps they will inspect it for me.[/quote]If you live in the USA, you can contact Velleman USA by phone (817) 284 7785. The support ticket is meant for non-US residents (since every ticket is handled from the Velleman HQ in Belgium).
I replaced the mainboard and just tested it, but unfortunately still have the same problem. Fortunately, the nonfunctional y-axis is now showing signs of life so I am glad I replaced the mainboard.
The stepper drivers are still too hot regardless of what voltage I set them to.
Another development is that I was incorrectly replacing the DRV8825 with A4988 when I was attempting driver tests.
So, I think I will purchase these DRV8825 from Amazon:
http://www.amazon.com/StepStick-DRV8825-Stepper-Driver-Printer/dp/B00S3Q9YZA/ref=sr_1_1?ie=UTF8&qid=1459290474&sr=8-1&keywords=stepper+driver
Please let me know if these drivers are suitable replacements for the ones included in the kit.
Over the last two months, I’ve gone through ten DRV8825s and all of them overheat and die.
Begging for ideas at this point.
Because of the Amazon link you gave it looks like you are in the USA or Canada.
If this is true the mains voltage is 110 VAC.
There is a switch in the power supply to change it from 220 VAC to 110 VAC.
Have you checked the output voltage of the power supply?
Should be 15 VDC.
When you are checking the reference voltage do you have your meter set to 2 volts DC?
Power supply is set at 110 VAC in, 15 VDC out. Meter was set to 2 VDC when testing.
I think I might just switch over to RAMPS since these mainboards and driver boards are basically disposable on my printer.
Your issue is quite curious as the drivers come with a thermal protection cutting the power to the motors if they become too hot. So you should experience layer shifting but not your drivers dying. You should try plugging your printer in an UPS or at least some net filtering device.
I think I might just replace the entire electronics system on the printer. I’m sick of wasting money on parts that die before I can even identify a problem.
Hi all.
It has been nearly a year since I purchased this printer and I am still having this same problem.
One development is that reuploading the firmware “fixes” dead drivers, not sure why.
I still cannot find a suitable reference voltage. I have tried every value down to the tenth at this point.
If no one can think of anything that might help, I think it might be time to part it out.
Thanks.
Today, I removed the first time (after I built the Vertex K8400 two years ago and printing a lot) the DRV8825 stepper motor driver. I was so astonished that the Driver worked so long time when I looked at the tiny smd parts. Some of them were really burnt black after the time.
When I replaced it with a new DRV8825, it came in a ESD package along with a little heat sink which is not yet mounted on the driver.
My question is: How should the heat sink be mounted to the Driver? Just with a heat transfer paste (cooler paste)?
But through movements, the heat sink can move in the paste and aluminium is dangerous to give a short-circuit.
Is there any othe possibility? A special glue which also transfers the heat to the heat sink?