In desperate need of help

Simplified Board 1 Machine: Originally K40 B&G

Board: C3D

Firmware: Smoothie; originally configured for a 40W.

Problem/ Question:
Howdy Folks …
I am in desperate need of help. Been fighting it for 3 weeks.
Bottom Line: My laser will not fire through C3D board. Attaching picture above.

  1. If I jumper G & L through the back of the C3D 4 pin connector (red line), it fires. Made sure pins were pushed all the way in.

  2. If I jumper from FET- to the top left screw terminal right pin (green line), It does NOT fire. I screwed the wire in, not just touching screw heads.

  3. Using Lightburn, head moves as it should. In picture, homing wires are removed for simplicity of picture.

  4. Using Lightburn, if I hit the optional Fire button, the laser fire light comes on (blue cirecle) but Laser does NOT fire. Brightness of LED depends on % entered. This is the only time I have seen this LED come on.

  5. Status LEDs are VMOT-Red, 3V3/L4/L1-Green, L2/L3-Flashing Green.

  6. Due to my fault, I was forced to replace the tube & LPS. Went with 50W tube & MYJG50W.

  7. I did NOT regenerate the firmware on the SD card.

Thank you very much in advance!

Please take some high resolution photos of the back side of your board, especially the box labeled “LASER POWER CONNECTOR”

Avoid connecting anything to the “laser diode out” terminals (green marks in your diagram) as you won’t be needing that with a CO2 laser.

First thing’s first, disconnect the laser power supply connector from the laserboard and put a multimeter in resistance mode between laser GND and laser FIRE pins. Fire the laser through software at 100% power and see if you get a low resistance condition when the laser is supposed to be firing.

Thank you for your reply.
Removed connector and setup test cut with 100% power.
When I ran the test with the DMM in resistance mode touching the Laser Fire and the Laser Ground, still had the same “OL”. As a test, I did the same thing touching the corresponding solder spots on the back of the board … same results.
The pictures of the connections are from 2 perspectrives plus the front of the board
Laser Power 3-1 Laser Power 2-1 Laser Power 1-1 .
Again thank you for your help.
Bobby

It’s not visibly burned, but I think your optoisolator may have gone out. If the red FIRE LED is illuminated that means the control signal is getting to the isolator but the isolator isn’t triggering. Repeat the test, but instead put the meter in voltage mode and put it across the “alternate PWM OUT” pins on the front of the board directly below the laser power supply connector. When the laser is firing, you should see ~5V on those pins. Then, repeat the test in resistance mode with the terminals across the “Laser Diode Out” terminals.

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