Bridgeport Series 1 control Retrofit with PMDX - 424 and Gecko G214s

[mini cooper]

Hi,
I'm new to the forum and would like to thank this community for a lot of ideas and information learned from reading this forum.

I am in the process of retrofitting a modern control onto a Series 1 Bridgeport CNC. The machine is in very good condition but as with any control from the late 1970's, it needs retrofitting. I have chosen to use the original stepper motors and power supply along with Mach4, PMDX-424 motion control board with a PMDX-407 spindle controller, and Gecko G214v drivers. I have been able to get some movement out of the steppers but it is erratic, sometimes they will move when jogged and sometimes not, and when they do jog, they move very slowly. Lately I haven't been able to get it to jog at all. As soon as I hit the jog button the Gecko G214v drivers go into protected mode.

All power supply and wires between the PMDX-424 and the Gecko G214 boards are shielded 18Ga. The information that I have on the steppers indicate that they are 8.2 amp, a little more than the 7 amps G214's have to offer, but I have read on some of the forums that people have done this but sacrificed some performance, as this is just a machine for me to play around with in my retirement, I am not in need of ultimate performance. I am currently working on wiring in the VFD and spindle controls.

I am including current profile package file, and a wiring diagram for additional information. Bare in mind that the wiring diagram is a work in process but the power supply, limit switches, and connections to the driver boards and motors are as wired.

Thanks in advance for any help that can be given.
Richard

[mini cooper]

Just wanted to add some pictures if they will help.
Richard

[mini cooper]

kind of a clumsy way to post pictures

[mini cooper]

Last one

[Steve Stallings]

Despite your nicely done wiring diagram, it took me a while to see an
issue that is likely the cause of your erratic operation of the stepper drivers.

Your wire #26 brings the Fault signals from the G214 drivers into the FAULT
input of the PMDX-424. This input is internally referenced to the isolated GND
system of the PMDX-424 just like all the other inputs. The FAULT output of
the G214 drivers is referenced to the same ground as the STEP and DIR
signals and that ground is connected to (and should be connected to) the
PCgnd of the PMDX-424. This results in both devices seeing the FAULT
signal having inconsistent grounds. As a first step in debugging this issue,
try removing the connection to the FAULT input on the PMDX-424.

If that cures the problem, we need to provide isolation using an opto-coupler
or a small relay. While Gecko lists the FAULT output as capable of 100 mA,
the actual chip driving this signal recommends 32 mA maximum.

Other items I would comment about are:

1) You have the power input to the VFD connected to the quiet output
side of your line filter. The VFD generates far more noise than is usually
coming in on the mains power input. I recommend connecting the VFD
to the mains side of the filter to help isolate noise generated by the VFD
from reaching the PMDX-424 and motor drivers. It is also nice to provide
a power outlet on the quiet side of the filter to power the PC and monitor,
which you did correctly.

2) Your mains power input is labeled as 120 VAC on each leg, yet you
show your computer and monitor connected across both legs which
will supply 240 VAC to them. Is this OK? The PMDX-424 is fine with 240.

3) You show your stepper motors wired in series. While this would allow
you to run them at lower current, the G214 drivers can supply 7 amperes
which is enough to run these motors in parallel. You might get slightly
less torque, but much better speed with your nominal 56 volt DC supply.