San Jose, CA hardware issue

[sweetwood]

I need some help trying to debug a hardware issue. It would be great if someone could come over and help me.

Here is what is going on:
computer > interface box > control box > cnc (steppers/sensors/etc)

The machine chirps about every second. It seems the power supply is resetting itself or something. When I unplug the cable to the computer, this noise goes away.

When the lights in the interface box come on (pin lights) (PMDX card), the CNC will move for a brief moment (x,y,z) as those signals seem to go live. It's a very disconcerting noise too.

With the computer unplugged, when I wave a wrench in front of the sensors, the lights flash in the control box card and I'm pretty certain in the interface box as well.

Anyway, all is not well here. I need help. I'm losing money by the second.

[sweetwood]

couple more things:

I'm running Mach3 and it's a woodcam cnc.
if you know someone in the SJ area, please refer them to me or VV.

-Glenn

[sweetwood]

ok, just measured some voltages inside the control box. i'm getting 19v on some spots that should have 5v. ah man. i could have sworn they were correct the other day.

[CarveOne]

You could have an open ground path in your wiring. Put the black voltmeter probe on the PSU ground terminal and verify +5vdc at the PSU 5v output terminal. Keep the black probe on the same PSU terminal while following the +5vdc wiring and checking each connection for +5v. When it changes to 19v look for a good ground connection at that device.

You can also turn the system off and check for continuity from the PSU ground terminal to each device's ground connection. If you get a higher ohms reading or an open circuit there is a grounding problem.

With a device that uses both 5v and another higher voltage you could be seeing a voltage drop through some of the device's internal circuitry if the 5v ground is not connected at the device.

CarveOne

[sweetwood]

thanks CarveOne. My power supply is 24v. It drops somewhere later on. Your suggestion is good though. I'll trace the voltage out. I just have to figure out where the voltage drops...or is supposed to.

[CarveOne]

That confirms my suspicion. 24vdc minus 5vdc = 19vdc.

CarveOne