Where do I go from here? Troubleshooting X axis

SRcnc wrote:

So today I swapped X and Y axis drives. The problem is still present. I did notice on my PMDX-126 there is an led on the J4 connector Pin 3 that outputs to the X drive. J4 Pin 3 is fed by parallel port cable pin 3. I retested my parallel port cable and it still seems to be fine. all pins have less than and OHM. I watched the LED's while the machine was homing. My homing sequence is Z, Y, X. I watched some LED's on the connector for Z axis turn on and off during homing. I did the same for Y axis. Then when X tries to home it does nothing but the LED stays lit. Any ideas?

Attached is a picture of the LED.

If you swapped the X and Y axis drives, the problem should have changed to the Y axis if it was the drive.

Did the issue show up on the Y axis?

No it did not follow the drive. So that rules out the drives for me. I ordered a new parallel cable 1 to 1 last night. Should be here Friday. I just want to rule that out before I start testing every wire and everything.

Okay guys I think I found my issue. I believe my X direction Gecko driver is burnt up.

I compared voltages on all 12 pins of X, Y and Z drivers. I found an anomaly on pins 5, 6, 7, 8 and 11.

On Y and Z voltages are as follows: Pin 5 - 13v
Pin 6 - 16v
Pin 7 - 14.37v
Pin 8 - 14.5v
Pin 11 - 6.97v

On X drive voltages are as follows: Pin 5 - 33.98v
Pin 6 - 34.0v
Pin 7 - 33.48v
Pin 8 - 33.46v
Pin 11 - 30.92v

I then noticed a burned looking chip on the X Gecko drive. You can see it in the picture.

I'm assuming the Geckos resistance circuit isn't working. I tested all three resistors and they all read around 1.470k Ohms. So I don't think the resistor is the issue.
I guess I need to order a new drive or see if it can be repaired.

Any guesses to why the chip would of burnt in the first place? I don't want it to happen again.

You know that would make sense. The X axis wiring was in bad shape. I thought that was the source of my issue. I rewired it after the issue started so it should be good to go when I get the new driver in. I am trying to figure out a solution for strain relief when the axis moves. The wires kind of dangle off of the stepper and drag in the chips and coolant. I have a cable chain on my Z axis but I don't think it would be a fitting solution for the X. Any suggestions?

I use anaconda sealtite on a BP knee mill. I assume the HF mill is small, look for some continuous flex liquid tight conduit that is rated for oil and heat resistance in the right diameter range. I think 3/8 is the smallest at .77 od so maybe a bit thick for your application. If you are in the US, McMaster carries some of that stuff.
Another option is to get Igus continuous flex robotic cable. They have it in oil resistant jacketing that is quite durable. You can probably get away with just using that and no outer conduit. I would add a nice cord restraint at the motor and drive box.

Thanks for the reply. I don't have pictures right now but I think what OT-CNC posted is worth looking at.