Hi all,
I have been building my own cnc router for some time using Wantai 57BYGH115-003B motors, DB25-1205F bob, 2 350W power supplies and the above controllers.  I have been able to jog the machine in all 3 axes many times but yesterday the z-axis failed to move. On looking in the electrical cabinet I find that 2 of the controllers are showing the red led. One of them is for the Z-axis and the other for the slave motor on the X-axis and both are powered fom the same power supply. When I power up the machine everything is OK with all green leds lit but soon after I switch on the computer (without even starting Mach3) I hear  a small 'groan' from the Z-axis and the 2 red leds on the controllers light up. I will try swapping over the power supplies but has anybody have any ideas what is wrong?
thanks
Vernon

Hi,
I have swapped the power supply to 2 of the controllers (1 with fault and 1 without) and the fault moved to the other controller so it looks as though the fault lies with the power supply.
Vernon

Latest information: With the system powered up (not the PC yet) I checked the supply voltage to the controllers and all 4 show 36V as it should be and the green leds are lit. All 4 leadscrews have holding torque and cannot be turned by hand. Then when powering up the PC, after 5 or 6 seconds the red leds on 2 of the controllers (powered from the same power supply) light up and the holding torque on those leadscrews is lost. The supply voltage to the 2 controllers now stands at 4V. I have swapped the power supply wires to different controllers and the fault moves too. To me this looks like the power supply is at fault. Can anyone suggest why the voltage drops, please?

Power all 4 drives from the good power supply and see if you get a fault.

That's what I needed - a bit of clear thinking. Thanks Graham. It worked. All 4 controllers powered from the 'good' PS and the fault has gone. So a new PS is needed. Thanks again.
Vernon