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Parallel Port breakout boards, motherboards, and dedicated accessories / PMDX-126 troubleshooting
« on: September 16, 2019, 05:59:06 PM »
Hello all. I am pulling my hair out troubleshooting my x axis homing issue. First off I bought this machine second hand. It's a HF converted 3 axis mill running on LINUX CNC. I had this issue when I first brought it home but after some fiddling it resolved its self.
The issue is during homing sequence it homes Z and Y perfectly then when it try's to home X the DRO will just keep searching but no movement at table.
Troubleshooting I have done is I replaced all wiring going to X axis. I know the new wiring is correct because if i swap X and Y plugs coming from my controller box the X axis moves and homes like Y axis would and I get no movement from Y axis.
I used a multimeter to test continuity of my parallel port cable and I did not observe any issues even when moving the cable around. All pins have less than 1 OHM even when I move the cable around.
If I check ignore limits I get a no limit switch active message.
I don't understand how this can be since I just milled a part last night. I start it up this morning and boom the issue is back.
Next I swapped my Gecko 251 drives with each other thinking it was a bad drive. The problem did not follow. So that rules out the drives for me.
I did notice on my PMDX-126 there is an led on the J4 connector Pin 3 that outputs to the X drive Gecko. J4 Pin 3 is fed by parallel port cable pin 3 I believe. 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.
I retested my parallel port cable and it still seems to be fine. all pins have less than and OHM
Any ideas?
The issue is during homing sequence it homes Z and Y perfectly then when it try's to home X the DRO will just keep searching but no movement at table.
Troubleshooting I have done is I replaced all wiring going to X axis. I know the new wiring is correct because if i swap X and Y plugs coming from my controller box the X axis moves and homes like Y axis would and I get no movement from Y axis.
I used a multimeter to test continuity of my parallel port cable and I did not observe any issues even when moving the cable around. All pins have less than 1 OHM even when I move the cable around.
If I check ignore limits I get a no limit switch active message.
I don't understand how this can be since I just milled a part last night. I start it up this morning and boom the issue is back.
Next I swapped my Gecko 251 drives with each other thinking it was a bad drive. The problem did not follow. So that rules out the drives for me.
I did notice on my PMDX-126 there is an led on the J4 connector Pin 3 that outputs to the X drive Gecko. J4 Pin 3 is fed by parallel port cable pin 3 I believe. 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.
I retested my parallel port cable and it still seems to be fine. all pins have less than and OHM
Any ideas?