PMDX-126 Irratic power

[zkmiller]

I have a PMDX-126/PMDX-107 setup that was working using a parallel port. I had some health issues and the system sat dormant for almost a year. I just upgraded my CNC PC to Windows 10 and decided to finally install my ESS and get things going again. When I powered up the control box the PMDX-126 started clicking and the LEDs would all flash on and off several times then go dark then start flashing all over again. If I had motors hooked up they would jump and stutter. This was with out changing any thing and no PC connected. The power to the mains connectors (set to 230v) appears to be jumping all over the place. If I disconnect the mains to the PMDX-126 the 240v reads stable at the terminal block. Has my PMDX-126 died? Hardly had time to break it in. Just finished building the CNC router table and control box when I had to set it aside while I dealt with cancer treatments. I guess my next move would be to completely disconnect the PMDX-126 and try and test it somehow.

Any helpful hints?

Thanks,

Zeke

[Steve Stallings]

It seems highly unlikely that the PMDX-126 could cause the mains voltage to change because it is internally fused at a fraction of an ampere and it should take much more than that to influence the mains voltage. Perhaps you have a bad connection in the wiring which brings the mains voltage into the PMDX-126.

The addition of an ESS to your setup will affect the power system internal to the PMDX-126. It was designed at a time when only the USB version of the SmoothStepper existed and the PMDX-126 internal power supply is not adequate to operate both the PMDX-107 and the more power hungry ESS. We recommend that the ESS be powered by an independent regulated 5 volt DC supply.

The addition of the ESS using power from the PMDX-126 could cause the PMDX-126 behave erratically, but it would not affect the mains voltage.

[zkmiller]

Thanks for the reply Steve,

I haven't connected the ESS yet. And as I said this thing sat for almost a year without being turned on. I will check all the mains connections and see if I can find a loose or bad connection. I will use and external 5v for the ESS when I connect it.

I have 240v to the box to power the Toroidal power supply, PMDX-126, and a VFD. It worked well when I first put it together last year.

Other than mains connections, would the input transformer or relay (the clicking sound) cause this?

Tomorrow I will take the board out of the control box and check it out.

Thanks again for the quick reply.

Zeke

[Steve Stallings]

If the mains voltage at J8 on the PMDX-126 is erratic, then it would cause erratic behavior of the PMDX-126.

The most likely cause of this kind of behavior is a loose connection.

If there were loose connections internal to the PMDX-126, they could cause erratic behavior of the PMDX-126, but you said that you saw the voltage going into the PMDX-126 behaving strangely and I do not think the PMDX-126 could cause that.

[zkmiller]

Well... I pulled the 126 out of the controller and put it on the bench. Switched it to 115v power, jumpered the E-Stop. Powered up fine and looks stable. Switched it back to 230v power and wired it to 230v in the control box with nothing else connected except the E-Stop jumper. Powered up and got the erratic behavior as before. The voltage across the mains terminals varies between about 150v and 190v. I shut it down and took one leg of the 220 and a ground connected to the mains terminals - switched back to 115v power and powered it up. Works fine. Could the switch be bad?

Zeke

[Steve Stallings]

A bad switch should not affect the mains voltage coming into the board.

Please try removing the two wires from the terminal strip of the board
without changing anything else in the box, then measure between the
two mains wires that were feeding the board to see if the voltage is stable.

[zkmiller]

So... I disconnected everything except the 126 and connected with power switch set to 230v. Voltage checked good and the 126 worked. I re-connected the VFD and all worked good. Connected the power supply and got erratic voltage again. With only the power supply connected to 230v input I get the  erratic voltage on one leg of the mains power. So, I have corrected the issue with the power supply and that has fixed the erratic behavior. Now to figure out why my 134 axis #3 does not work. That is for another topic.

Thanks for holding my hand through this issue.

Zeke