Odd Laser Power Issue

[Brian Leavitt]

Our 60-watt Universal X-660 has been having an issue with low power for quite some time now. It's been going on for a couple of years, on and off, but since I rarely use the machine, I have been lackadaisical about fixing it. Now I really want to get it fixed up again.

At first I thought it was an issue with the laser tube because the power output was only measuring at 37 watts the last time it was checked. After that I just kept using it, but with higher power settings to compensate. During that time, the output seemed relatively consistent. A few months later I decided to just go ahead and order a new laser tube. After that went in, everything was fine for about a week, but then I noticed that the output was decreasing again. So I swapped laser tubes between the X2-600 and the X-660. Both tubes worked fine in the 600, but both had decreased output when installed in the 660. I let it go for several more months and just didn't use the machine. So fast forward and I replaced all of the optics in the 660 a couple of weeks ago. Again, after doing so, everything seemed fine... until yesterday. I was running acrylics on there and the power output is definitely down again.

Laser tube is less than a year old; optics are a couple of weeks old; everything is clean; beam is aligned; table is level; and all belts and bearings are about two years old, and have seen little use.

Anyone have an issue like this? I'll be contacting Universal Tech Support, but I was wondering if anyone had any ideas.

Thanks,
B

[Scott Shepherd]

Power supply would be something to check.

[Brian Leavitt]

Power supply would be something to check.
Thanks, Scott, and sorry for the delay in responding.

It's not a power issue after all. I rented a power meter and the laser is averaging 66 watts on a 60 watt tube. I have attached a photo which best illustrates the problem. The top ornamental was engraved with the X2-600. The bottom was done by the X-660. I also measured the depth of engraving and the X2-600 engraved to a depth of .006, while the X-660 engraved to a depth of .002 on this piece of acrylic.

All of the laser optics are new, the tube has very few hours on it, and I checked beam alignment again. The power supply is supplying the laser tube with a consistent 47.6 volts, and tested the modulation, which also checked out OK. It also has the same problem no matter which lens I use (between two 2.0 lenses and two 1.5 lenses)

I'm really stumped here... :confused:

[Richard Rumancik]

Brian - are you able to put the known-good 50-watt laser cartridge on the 60 watt machine? If so, this could help isolate where the problem is coming from.

[Brian Leavitt]

Yes, sir - I switched the 50 watt tube from the X2-600 (good laser) over to the X-660 (bad laser) for testing and encountered the same issues. The 60 watt tube from the X-660 works perfectly fine in the X2-600 as well.

[Guy Hilliard]

It may be an alignment issue (check with a piece of tape over the hole in the flying optics), or if you have air assist the air cap on the port where the beam enters the cabinet (back left corner) may be loose - improperly mounted, or the air cone is interfering with the beam.

[Richard Rumancik]

Ok, sorry, I missed that in the original post. It would imply both tubes are good. So what is left on the 660? You seem confident about the optics in the 660 (bad machine) so it seems to leave the laser controller/mainboard or whatever board is making the laser lase, or anything that connects the two.

A power test could exercise the tube in a different way than what happens in real life during rastering or vectoring. You said you checked modulation - you mean with a oscilloscope?

I take it that Tech support has been unable to make suggestions?

[Brian Leavitt]

Thanks, Guy - I have aligned the beam/checked the alignment several times. Once after putting in the new optics and then again after removing and re-installing the collimator a few times. I just aligned it again this morning. This machine does not have air assist.

[Brian Leavitt]

Richard - by modulation I meant I checked the CPU's modulation of the laser power. It's supposed to read 5 Vdc between two wires at the laser tube plug at 100% power and I got 4.64 Vdc, which ULS says is OK. According to the test, this would indicate a bad laser tube, but this has already been disproved.

I have another test I want to run, but it'll have to wait until tomorrow as I'm heading out for the day.

Thanks for the replies!

[Brian Leavitt]

So I removed the NEW collimator and the engraving improved dramatically. With the 2.0 lens and no collimator, I got an engraving depth of .0045 and the ornamental engraved much better. On the X2-600, with the same settings on the same piece of acrylic, but with the 1.5 lens, I get a depth of .0065, which is much closer to the difference I would expect, due to the differing power densities.

I started wondering, yesterday, when I was rechecking the beam alignment again for the billionth time. The red laser pointer was going in and out of focus as I moved the lens carriage around the table.