View Full Version : Sanyo Denki stepper motors

24-04-2013, 08:54 PM
This is a new setup, Sanyo Denki stepper motors, Kinco 2M2280N high voltage drivers with a PMDX 126
bob.I have a big problem with it. I cant run mach3 with it because I have 30 to 70 ACV on the stepper motor casings. Tested the stepper motors, there are no leaks. Dont know what to do, cheacked the wiring its ok. Thinking about changing the drives? or the lot
Thanks for any help


24-04-2013, 11:12 PM
Have you got everything grounded correctly?

24-04-2013, 11:49 PM
Everything is grounded correctly but the noise is playing havoc with mach3

25-04-2013, 08:30 AM
Forgot to say I have the 70V when I take the earth of the motors, so where is it coming from. The only electical thing on the machine are the motors,

25-04-2013, 06:05 PM
Sounds like an earthing/sheilding issue, and as you're using 5V for signals, any shortcomings will quickly become apparent. That's why commericial machines use 24V for control circuits.

The 70V is simply a result of what happens when you place a lump of metal next to something containing magnets and voltage.
In you're wiring, have you inadvertantly created a ground loop somewhere?

25-04-2013, 06:57 PM
With just one driver conected the problem is stil there.
The high voltage side is wired correctly and control is
The negative side of each PLS and DIR input to BOB ground
PLS+ to step
DIR+ to direction
Getting ready to throw every thing out and get a closed loop stepper system

25-04-2013, 07:21 PM
Back to basics, have you used sheilded wiring, and tried to keep power and control wire routing as seperate as possible?
And avoided having them run randomly across each other?

25-04-2013, 07:33 PM
Sheilded wiring and power, control wires are seperate,a clean control box

25-04-2013, 11:32 PM
Make sure your shields are only connected at one end of the cable?

25-04-2013, 11:33 PM
I did have a link to a document that detailed grounding/sheilding, and how things should be wired, but I can't find it.

Have a read over this thread - GROUNDING - what is the correct way to ground a CNC machine? (http://www.machsupport.com/forum/index.php/topic,9587.0.html)

Found it - http://www.automation.siemens.com/doconweb/pdf/840C_1101_E/emv_r.pdf?p=1
Might take you a few reads to digest all the info, but explains things pretty well.

26-04-2013, 06:22 AM
Shields are only connected at one end of the cable and the earth is connected to the mains earth.
Thanks for the doc

26-04-2013, 08:40 AM
Ok, ripped every thing out of my control box and tested the drivers.
I have 100VAC on the earth and 230V on R+ of the motor connection.( the 3 drives)

26-04-2013, 03:57 PM
Is that with the earth connected?
If it is, I'd be checking the earth on the socket you're using to power it.

26-04-2013, 05:01 PM
No just the P&N.
Im taking the measurement from the mains earth to the earth pin on the driver

26-04-2013, 09:27 PM
Unless the case is grounded, you will nearly always get some kind of voltage reading between the case and ground. If you put any bit of metal near something that is either switching power or containing an active inductor, and you will get power generated in that bit of metal.

The case has to be properly grounded to ensure that power is dealt with safely, and to minimise noise transmission.
All grounds should come back to a central star point, and only be connected at one end to prevent ground loops.