Sudden loss of motor power VSD-A v2

[ftec]

I've got 3 BL300 motors in xyz motion. Suddenly, after working just fine for months, I'm now getting a weird loss of power in the Y axis. This happens only when the spindle is running and only for the Y axis. The error is not generated with extremely slow jog speeds.

When the spindle is on and with very slow motor speed, even a slight touch on the motor axis generates external stop in Mach and stops the whole system, but VSD-A error leds are not lit. On higher speeds the axis advances just a mm or so and the halts.

What could be causing this? Perhaps a bad contact somewhere in the wiring? From where should I be looking for the reason for this.

I would appreciate a quick answers as I'm in the middle of a job that needs to be finished.

Thanks,
Risto

[ftec]

PS. There is no sign of loss of power when the axis is not moving when testing manually the motor shaft.

PPS. This seems more and more weird when I test a little further: When the y axis is kept put, it's power is OK. When I start and increase the speed of the spindle the power of the y axis shaft starts to diminish. When I stop the spindle the power returns back and no error in VSD-A and it locks back to position. The same power loss does however not happen to X and Z axis while all 3 VSD-As are identically connected and been working fine so far. The spindle's VFD drive is outside the cabinet and there are no VFD related power lines going near any of the VSD-As. The only thing they share in common with the spindle is the CNC4PC C11 BOB. Can anyone make sense of what could be happening here?

[ftec]

Well, found out the reason.

It really was the C11 BOB and its Safety Charge pump ciruitry. I've changed several of these cards for warranty because all of them had the same problem that the charge pump pin 17 never gave a low enough low voltage (always stayed above 0.7V). I finally fixed this by adding an external pull down resistor to make it work. Now, in the course of time the resistor makes the high voltage to drop too low.

Thanks,
Risto

PS. If you wonder how it affected the VSD-A power the reason was that we have a safety circuitry and the too low high voltage caused the signal to the VSD-A disable input to oscillate.

[Xerxes]

I'm happy that the solution is found! Also my apologies that I somehow managed to miss whole thread and not to provide help.

[ftec]

Originally Posted by Xerxes I'm happy that the solution is found! Also my apologies that I somehow managed to miss whole thread and not to provide help.

No problem

At least now it has been proven that if you need to reduce motor power with an uneducated manner just pulsewidth modulate the drives disable input.

/Risto