I have an unusual problem with a JPT MOPA 60W fiber laser.
Up to now it has been working without issues, apart from some initial overheating problems.
Recently, however, something strange has started happening.
At random moments the laser stops engraving. The red preview dot remains at the exact spot where the engraving stopped. LightBurn does not show any error, and the job time counter keeps running as if everything were normal.
I’m starting to notice that this happens more and more often.
What was overheating? I am a diode guy but that sounds like the controller did(does) a reboot. A likely cause is a power supply dropout. Could be either a power connection or a bad power supply.
Right after purchase, the laser source used to shut down after longer operation at high power due to overheating.
I added additional fans and the problem disappeared.
Today I’m going to open the enclosure and see what’s going on inside
I suspect the laser is heavily clogged with dust inside. Do you think dust could cause this kind of problem?
Is that a trick question? The soot/dust on the cooling fins act as an insulator. I just cleaned my 40w/20w laser module last week and was stunned it had not overheated, at least I did not know if it did.
Not stupid. First laser always comes with a huge learhing curve.
You have a Fiber laser, and I have not seen your setup, so I am not sure where it can get gummed up. But I do know if it generates smoke, that smoke will go where you do not want it.
So, I opened the enclosure and cleaned the laser. There was much less dust than I expected, especially considering that I do a lot of deep engraving.
The laser works more stably now, but it can still stop occasionally.
However, I think I’ve noticed a pattern. The laser stops when working at a frequency of 144 kHz and 90% power.
When I don’t use this frequency and work at lower ones (20–48 kHz), the laser hasn’t stopped so far.
I’m not saying that this isn’t the case.
However, the laser worked without any issues for an entire year, performing exactly the same tasks.
Until now, there were no such problems.
I checked virtually every connection. I cleaned the entire inside of the laser. I added additional ventilation. I tested two other good quality USB cables.
None of the above helped — the laser was still stopping randomly.
In a moment of desperation, I remembered an absurdly expensive USB cable that I use for data transfer from my camera.
Using that cable solved all the problems.
Most likely some kind of interference was occurring and causing signal issues. This is only an assumption, as I’m not an expert, but logically it’s the only explanation. The camera USB cable has much thicker insulation.
I hope my problems and stress are finally over. Maybe this description will also help someone in the future who runs into the same issue.
Thank you for your interest
I think most of us think usb stinks … It should be dependable as it’s a differentiated signal that should be impervious to most emf fields or interference.
A lot goes on between the connections and I don’t know it either, so we end up living with it. I have a co2 with a Ruida controller and I use Ethernet exclusively with it.
Good find! Could you share the brand, length, and origin of this USB cable?
It might be interesting to test the previous problematic cable further: to try clip-on ferrite chokes, or to experiment with a USB isolator. Or… if you are currently using a mains-powered PC (with a shared ground to the mopa)?, then I wonder if it would it make a difference to switch to a battery powered laptop?
Another thing to consider is USB cable routing - the cable’s proximity to the MOPA source may matter, perhaps one side of the box has worse interference than the other?
Oh well, hopefully you have seen the back of this issue!
The USB cable is 4.6 m long – TetherTools TetherPro.
Using a laptop instead of a desktop PC could indeed be a good solution.
For now, however, I’ll stick with this cable since it works, and I probably won’t change anything
I had a similar issue with a CO2 laser, it would randomly reset, after trying various mains filters and things the fix was to feed the laser with a cheap USB hub between the laser and computer, not sure why it worked, but it did!
I had a similar problem. By dropping the power to below 80%, regardless of the frequency and Pulse width, it has become fairly stable. Short runs, 90-95% no problem but when doing coins, have to drop the power. BTW, this is a 80W MOPA
