[mikemccand]

Hello, I purchased a G Weike LG900N 80W CO2 laser cutter ~1.5 years ago, and it has worked great at mostly light usage, until now.

But recently it developed this horrifying problem: the laser head sometimes loses the ability to go left. When I press the "move left" button, it goes right instead. Same thing when it tries to cut. When I first power it on and it tries to home itself, it just winds up banging onto the rightmost rail with a scary "BANG BANG BANG" sound, until I reset it.

I thought perhaps the X axis stepper motor was bad, and replaced it, but that did not fix it. Same problem.

I thought the problem was maybe caused by heat, because it would get into this state after quite a while (maybe an hour) of usage, and sometimes turning it off, letting it cool, and then on again, might fix it. But it's been off for days now, and I turned it back on and the same problem is there.

Has anyone else seen this problem? Could it maybe be a loose wire? How do these stepper motors know which direction to step in, when commanded? (Like which wires get which volts?) Or maybe a short circuit in the control panel (the board that has the buttons that I press)?

Any suggestions on how to debug or fix it? I could try replacing the whole control board, which seems to be on the lower back of the machine. I'll try to get its exact part number.

Thanks!

Mike

[mikemccand]

I took pictures of the controller (RDC6442S-B(EC)) and the X/Y/Z drivers (not sure what part number they are, but they have big black heat sinks on them), and attached here.

I think I will just try to replace that controller first, and if that fails, the drivers.

I found a newer Ruida controller, the RDC6445G, on Amazon. Do you think I could just upgrade to that newer controller as long as I can physically mount it in the machine, along with its control panel? Or should I try to find precisely the right model?

[Dean448]

Pin 1 off your controller is X direction
Looks like it has an LED showing state to help know what signal comes from the controller. Left on or off and right the opposite.
I would remove and reinstall that connector at both ends.
So the signal out of the controller is 5 volts. It connects to a stepper driver that drives the stepper motor. Loose wires at to stepper wouldn’t show up as a direction change.
Most likely the problem is in the pin1 wire.


Sent from my iPhone using Tapatalk

[mikemccand]

Pin 1 off your controller is X direction
Looks like it has an LED showing state to help know what signal comes from the controller. Left on or off and right the opposite.
I would remove and reinstall that connector at both ends.
So the signal out of the controller is 5 volts. It connects to a stepper driver that drives the stepper motor. Loose wires at to stepper wouldn’t show up as a direction change.
Most likely the problem is in the pin1 wire.


Sent from my iPhone using Tapatalk

Wow!!! You nailed it!!! That precise pin (pin 1 coming out of the controller) was not firmly screwed down, just sort of loosely touching. So I guess heat and vibration over time sort of shook it a bit loose. It's a miracle it worked at all for the past 1.5 years

Thank you, back in business! And those LEDs will prove helpful for future debugging.