[cjpryor]

Question: Are there any other stepper motor drivers I can use with a Microkinetics CNC Express mill other than the original DR8010? I suspect I could replace them with DM8010s but am not sure it is worth the additional expense.

I searched the web and the forums for an answer but did not find any. I am not an electrical engineer but can figure things out if given enough information.

After encountering this problem I learned that I probably should have removed the cables before using the mill manually because the motor will act as a generator and send current to the electronics in the Drive Rack. I tried disconnecting the cables and noticed that it manually turns much smoother now with no resistance. When the cables are connected there is a definite felt resistance when I turn it manually.

Before I describe the problems I am encountering, here is some machine information:

Microkinetics CNC Express Mill
Model # 999-6500-000
Serial # 0119
Motion Controller: MN400 (except mine is not USB)
Stepper Motor Drivers: DR8010
Stepper Motors:

• one is: 1.85V 6.6A slosyn type kml08f318
• The other two have faded labels so I am not sure but look like this

Background:

I purchased this cnc mill used several years ago and it was working fine. I then only used it manually for the next couple of years. This weekend I went to use the CNC capabilities and encountered the following problems:

Problem description:

• One way only computer controlled motion on the Z axis
• No X axis motion
• Full Y axis motion
• Swapping cables from the mill to the back of the Drive Rack verified that motors on mill are working
• Removing the cover from the Drive Rack revealed that one stepper motor driver (DR8010) was not getting power
• Found a burnt fuse for that DR8010
• Replaced with a fuse from another DR8010 and powered up the Drive Rack which resulted in the fuse immediately blowing

I do have an ohm meter and saw on another forum how to check signals to the motors so I will do that to confirm the problem.

After that I am thinking of moving the partially working stepper motor driver to the other not working position to see if the problems follow it. Then I might try moving the good one to other positions to see if they work. I am hesitant to risk breaking the one that is working as part of my diagnostics.

Thanks in advance for your help.

[arizonavideo]

Blowing the fuse generly means you have a output transistor shorted out. You can try to replace them if you can find out what they are. they cost about $2.00 each most of the time and are fairly easy to replace. I bet the whole board cost a good amount so I would do that first.

The outputs work in pairs and you have 4 for each channel. A meter most of the time will show which one is shorted but you need to replace them in pairs.

I would call Microkinetics if they are still around and I bet they will have some outputs around.

[cjpryor]

Thanks. I have been communicating with Microkinetics and they have been very helpful. However, I still did some things on my own that I am sure they would not approve of. For your entertainment, here is what I have done so far:

1. I swapped locations of the stepper motor driver (SMD) that was not powering up (blown fuse) with the one that was controlling the z axis (which had one direction only). I reset the current dip switches for the new locations since the motors are different with different current requirements.
2. While they were out of the chassis I inspected and cleaned both. I could not see any visual indicators of problems.
3. After reinstalling them, I placed a slower blowing fuse (fast rather than very fast) for the SMD that was shorting (which is now controlling the z axis). I figured the SMD was blown anyway so I couldn't hurt it any worse than it was. I hoped the fuse would still be enough to protect other electronics in the system.
4. On power up I saw sparks underneath the SMD that was not powering up before so I hit the kill button immediately.
5. Figuring the fuse was blown I tested it but it was fine so I replaced it and applied power again. This time there were fewer sparks and the SMD powered up! It never sparked again after several cycles of power but I still call it sparky now.
6. I tested operation and I have full motion except for the z axis. I was expecting the z axis problem to follow the SMD that was on the z axis but it didn't so that SMD is fully functional. The SMD that did not power up and sparked is controlling the z axis but the problem is the same as before with a different SMD so that makes me think the problem is in the cable connector not the SMD.

I am going to trace the wires from the SMD to the cable connections, clean the cable connections, and try again. Hopefully I'll get out of this with only the expense of replacement fuses.

Blowing the fuse generly means you have a output transistor shorted out. You can try to replace them if you can find out what they are. they cost about $2.00 each most of the time and are fairly easy to replace. I bet the whole board cost a good amount so I would do that first.

The outputs work in pairs and you have 4 for each channel. A meter most of the time will show which one is shorted but you need to replace them in pairs.

I would call Microkinetics if they are still around and I bet they will have some outputs around.

[cjpryor]

Everything works now.

!!!

[Contract_Pilot]

Out of the 6 dead DM8010's that I got on ebay all of them had bad SCR's S4010LS2 and a couple had bad regulators TL783C just an FYI Click here for Microkinetics DM8010 Driver Test Procedures