Tri Power Frying motherboards

I have a Tri-Power Patriot. Ran fine for a year then motherboard fried over the summer. Switched out with a good computer and motherboard fried on startup. Tested voltages and thought I had a ground problem in outlet. Fixed that problem and installed 3rd tower. It ran fine for 3 months, but sure enough went to boot up today and motherboard fried. I feel like it has to do with the 25 pin cable. Unit was installed by Camtronics and not modified. My question is... The 25 pin connection on the machine side is just a circuit board that connects to the gecko drives, there is no circuitry on this board. So basically the Gecko drives are driven straight from the parallel port. Should there be a breakout board between the computer and the Gecko drives to isolate the signals? I feel replacing this "dummy" board with a breakout board, it would prevent unwanted signals getting to my PC. Has anyone had any similar problems or any suggestions? Sick of replacing PC's. Thank you.

A break-out board is a very good idea. It isolates the PC from the equipment. Here is a good write-up:

https://www.cnccookbook.com/cnc-breakout-boards/

Cheers,

which Geckodrive stepper drivers do you have ?

most of the Gecko stepper drivers have opto isolators on the step , direction and enable inputs
if i remember correctly only the G250 & G251 don't have isolated inputs

with AT or ATX PC's the mains earth is connected to the printer port pins 18 to 25 via the
power supplies black wires connected to the mother board

what inputs do you have connected to the PC inputs ?
just the E-stop switch or do you have limit & home switches connected as well ?


a breakout board with opto isolators on the inputs will help
assuming the Gecko stepper drivers have opto-isolated inputs
you don't want a breakout board with opto-isolators on the outputs !!

one example breakout board is this
Attachment 403984

one thing to note is the input common for the E-stop & limit switches and
the 10V analogue output common are connected together
so you need to ensure the speed control input is not live !!

as it is with speed control boards like the KB electronics KBIC240D
or Sieg FC250J

what speed control do you have for the spindle ?

photos of the machines electronics will help


John

Thank you for the replies. I am running Gecko G-201 Drives. The spindle is not a VFD its just a 120v electric motor that I control manually. The gecko drives get a common +5v from the computer via USB connection. There is definitely a voltage difference somewhere because when I run a probe from my machine to the physical ground, it will show a few volts. I feel like isolating the drives from the computer should fix this problem. I don't get why a breakout board was not used as some sort of protection. I decided to purchase a smooth stepper with breakout board and replace current setup with that. It's getting harder to find a 32 bit computer with parallel port. I'm going to run it with Ethernet and a laptop. This way the computer will be isolated. I can also take computer inside when I am done using it. Hoping this will fix my problem.

Update: Converted everything to smooth stepper and run off ethernet. Machine runs much better with no problems. Also nice knowing the PC is totally isolated from machine. It was almost a blessing is disguise fying the motherboards.