View Full Version : Motor Not Locking Up on Power Up

Mon 12 November 2012, 22:23
Hi All

I have been trouble shooting a CNC for a fellow surfer recently.
While a fundamentally good machine it has shown me clearly that trouble heads your way if you don't do things right in the first place.

The problem I am having is that one motor will not lock up when the control box is powered up.
The beauty of this problem is it does not involve Mach3, the PC etc as normally on powering up the control box the motors lock.
The other axis lock fine and I have swapped the non locking motor with another known good motor that does the same thing. Any Ideas ??


Gerald D
Mon 12 November 2012, 23:03
A loose connection between drive and motor, no power to drive (loose connection).

Mon 12 November 2012, 23:25
Thanks heaps Gerald

We have found loose soldered connections all over the place, so I'm guessing there is one more yet to find.
The build has used too many and low quality connectors between the control box and the motors.

Might just run a single cable with no connectors out to the motors from the Gecko's.


Tue 13 November 2012, 02:32
Trial & error works fine when you are lucky & when Murphy is out of town.
I would prefer to narrow down the search by checking for wire continuity with your multimeter? Won't take too long, only 4 wires to check.

Discontinuity may meant many things, loose connection, poor soldering joints, inferior connector, bad cable/wire (don't laugh, this happened to me before)... etc.

It might be a defect driver too.

Can't think of anything else other than that.

Tue 13 November 2012, 03:03
Hi Ken

Thanks, already swapped the driver out but did not test the continuity as you suggest.
I am banning solder joints after seeing what trouble they can create.
For the record my machine has no solder joints, probably explains why it goes so well.
Tomorrow I'm back at it so until being beaten down again I'm full of confidence :D


Tue 13 November 2012, 04:00
The best connector is NO CONNECTOR!!! :D:D

Tue 13 November 2012, 23:08
Might just run a single cable with no connectors out to the motors from the Gecko's.
Worked for me.

Wed 14 November 2012, 04:30
Pretty much rewired the control box and then did the VFD for good measure.
I replaced the cable to the motor that would not lock up and removed all connectors except for installing one good quality military grade screw terminal connector to the motor for a quick disconnect.

All other cables into the control box had their connectors removed, an unbroken cable passed though new cable glands and the ends boot laced to connect into the Gecko's. A massive improvement in reliability has been achieved.

Thanks everyone for you comments and assistance.