Laser stopped cutting, lasering, firing in the middle of a job and will not pulse or fire. Laser Head still moves but does not burn
Preface: This article covers a few tests and checks for when your laser is not firing. Some of the tests are visual inspections while others will require you to change the machine configuration and run diagnostics
Quick Start:
Nova 24 LPSU, OPTO, Test Button and mA Meter Location Help Video
Complete Guide:
In the guide below there are many things to check that could indicate a particular failure, either in signal to the LPSU, the LPSU itself or even power to the LPSU. Many different checks need to be performed to rule out the non-causes.
Things to Check if the laser is not firing at all:
Check for 120V Feeding the Power Supply:
The Machine laser Power Switch must be On
Please make sure Laser Power switch and Main Power switch are both in the On position and the main Contactor is pulled in.
Main Contactor must be Pulled In
The main contactor is located in the electronics bay on the right side of your machine behind the blue door(s).
| Main Contactor Blue Plunger is Out (Off) | Main Contactor Blue Plunge Pulled In (ON) |
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If the
Main Contactor
is not pulled in and you have both switches on then its function needs to be checked:
The
Main contactor provides 120v power to your LPSU. If your Laser and Main
switch are both in the on position but you do not have power
indications on the LPSU, lets check the main contactor. Unplug the
machine from the wall and check that the wires terminals on the Main
Contactor are landed and tightened down.
Visually Checking:
Locate your LPSU
Nova 35, 51, and 63
Located on the back of the machine, behind the blue door to the Left of the exhaust outlet
Nova 35,51, and 63 General Location | Example of the LPSU |
Nova 24:
Located on the left side of your machine behind the lower blue door.
Nova 24 LPSU Location | Example of the LPSU |
For the Nova 24:
You
should have some LED's on the power supply that are illuminated. If you have the Chiller on and connected, the yellow LED for Water Protect (WP) should be illuminated.
Your
Nova 24 Ammeter is analog and you will not have a digital screen. Also check to
see if the LPSU case fan is running.
For the Nova 35, 51 and 63 Lasers:
If
the laser power supply is 'lit up' and/or shows something on the
digital display, then it should have power. If you have the Chiller on and connected, the yellow LED for Water Protect (WP) should be illuminated.
Note: The machines before Apr. 2018 had been installed another type of laser power supply, like below.
Loose Terminations on the Opto Isolator Board:
Check
the terminations circled on the Opto Isolator Board for tightness.
After tightening, test run the machine to check for laser output.
Loose Connection at the Ruida Controller CN5:
Locate the Ruida Controller on the right side of the machine in the electronics bay behind the lower blue door(s)
Lets check that the green connector is fully seated and none of the wires are loose.
Connector is not Fully Inserted | Loose Wires | Correct Installation |
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Checking Voltage With a Multimeter:
Video Demonstration | Picture Demonstration |
On the 3 Pin plug, you will have a Brown L wire, Blue N wire and Yellow\Green Ground Brown to Blue - Should have ~120vac Brown to Yellow\Green - Should have ~120vac Blue to Yellow\Green - Should be ~0vac If you have 120V on Brown to Blue but the screen is not lighting up, or LEDS\Fans are off no matter what you do, then the LPSU is dead and needs to be replaced. |
Things to Check if the laser is firing but is weak or not cutting or engraving as expected:
Material Settings:
Check that you do not have your min power set too low to where the sharp corners and tight radii are not cutting. Up the min power level for the cut layer to be adequate for cutting the material for when the laser head is traveling less than 10mms.
Symptoms of a Bad cut | Example Layer Settings |
Corners and tight radius curves do not cut all the way or even fire at all (Back Side is shown here) | When the laser head is traveling 10mms (even is layer speed is set to 100mm/s) the Nova Laser will run the Layer Min Speed, in this case it is set to 1% which is too low to fire or cut the material |
Layer Speed Set to 25mms but on Corners and Tight Radius Curves, output is 1% | Example of Proper Settings for Reduced Power for Corner\Tight Radius Cutting |
Red Button Test:
Run this as a base test, it is one of the first tests you should perform.
Tube Check:
Visually inspect the laser tube.
-Look at each end of the tube, checking for contaminants and signs of charring from the electrodes.
-Inspect the wiring to the tube for thermal insult or charring
-Inspect the tube for cracks. Carefully inspect the body of the tube looking for hairline cracks
-Inspect the tube for inner jacket failure. Your outer jacket should not be full of water, your tube is not an aquarium.
-Video the tube while it is firing, look for a steady beam through the center of the tube
Pulse Check At Tube Exit:
Check that the beam output is not a Halo and is a dot.
Current Test with Opto In place:
Run this current test and compare the results. Assuming that the Red button test was not abnormal, otherwise skip.
Current Test With Opto Bypassed:
If you got funky numbers in the above test, it may be good to bypass the Opto board and re-run the test. Assuming that the Red button test was not abnormal, otherwise skip.
Current Test With Channel 2 (Opto in place or bypassed):
If you got funky numbers in the above test, it may be good to try Channel 2 and re-run the test. Assuming that the Red button test was not abnormal, otherwise skip.
Check Alignment:
If your Tube and LPSU pass the above tests, then they are making power and you just need to get that power to the material. Do a spot check on your alignment and check all 3 mirrors and your lens. We suggest pulling mirror 3 out of the laser head to check as it is dark inside the laser head.
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