Symptoms:
The laser job pauses or cancels or stutters during a job run.
Testing:
Run the same job with the lid open. This disables the firing but otherwise the signals into the motors and the laser are exactly the same. If the job runs successfully always with the lid open but pauses or stutters when the lid is closed (eg the laser is actually firing) then 99% chance you have an EMI or grounding issue.
Explanation:
The laser tube works like a fluorescent light bulb with a large initial strike voltage of between 25,000 and 35,000 volts. This initial strike voltage causes a lot of electrical noise and static electricity build up on the back of the laser case if not properly grounded.
Solutions:
Check grounding wires
Ensure grounding of the laser tube is correct with a multimeter by checking the ground point has conductivity to all bare metal points. This is essential the metal housing protecting the laser tube is grounded. If it is not, the high voltage discharge will create a static electricity build up that when discharges will cause computer lockups resulting in pauses. Sometimes grounding pins may slip onto painted parts forming a bad ground connection or the wiring of the plug the laser does not have a proper ground wire. These conditions will result in EMI and lead to pausing from static electricity discharge. Try changing outlets and use a multimeter forms no resistance contact between the points listed in the below diagram.
Ensure you have clean water in the cooling tank
Another common cause of EMI issues is you have dirty water or used non-distilled water. The laser tube uses water cooling and if any metal particles exist in the water then these will cause EMI discharge to the electronics and result in cooling. Flush the laser tube thoroughly at least once a month with distilled water to prevent this from happening. Distilled water has minimal conductivity compared to water that has any salt or metal ions such as would be present in tap or dirty water.
Bad tube or PSU
A bad tube will also cause EMI. The laser tube fires 25,000 volts and if it has a break in it then it will jump to the case instead of through the ground connection. Replace the tube and if not fixed, replace the high voltage wire and the power supply. What can happen with prolonged use of a bad tube is the 25,000 volt jump will take the shortest path and sometimes that's through the high voltage wire causing a break point in the wire or flyback transformers in the power supply.