Hey everyone, I’m trying to find out how to start troubleshooting this issue:
My OMTech 60w laser started pulling a steady 22mA this morning when cutting at 80% power. 15-18mA is the suggested power rating and I’ve never seen it go past 20. The mA meter I installed and the digital readout on the power supply had the same readings.
Is my tube taking a dump? Power supply? Any pointers in the right direction are appreciated!
Sounds like a supply and/or tube.
Hang around, someone else will comment…
I doubt that it’s the controller.
I was under the impression that tubes generally ‘open up’ when they go south. I’d expect less current?
Is the cooling temperature held constant?
The current temps hover around 13-15c; it’s hooked up to a a 5200 chiller. I would not be surprised if the tube was going, it was treated poorly, but since I was also thinking the tube would draw less power as it fails, I thought the problem was elsewhere.
I would just try to hold it under about 20ma, increase the temp to 18-19 and run it until it doesn’t cut the same. You will find that the cutting performance doesn’t really change much at the upper amp range of a tube.
If your a business and don’t want downtime then order a replacement tube just to have on hand.
My old 50w power drifted high at times, which didn’t really cause an issue.
They do wear out and in the end 60w is on the low end of what you need these days. So it’s an upgrade opportunity
I’m 99.9% sure I have it on the black wire between the laser’s power supply and the cathode. I installed it 5-6 months ago.
If you didn’t install it properly it would either be burnt up or non operational. So I’m confident you have it in properly.
Since these are negative resistance devices, maybe the current draw during failure is not determinable…?
What are you going to change out? 
lol, yeah, that’s where I figured this was going. 
Since my options are either the power supply or the tube, and I’m going to need a new tube sooner or later anyway, I guess I’ll go that route. It’s the original tube, so it probably wasn’t that great to begin with.
Poked around a bit and it looks like I’m going with one from Cloudray. Very tempted to make an extension and upgrade to something bigger. 
I have a 60w PS and upgraded to a 90w tube. So far it’s working great. Probably not recommend but should work as long as you don’t push the power too high. My observation is that just a tube change alone makes a big difference in power. Power supplies aren’t that expensive either.
I put a different tube holder (Russ Sadler) in mine and the tube now extends past the cabinet. I 3d printed one for tube protection. I found those extensions are not easy to come by.
I’d suggest the upgrade… If you upgrade you’ll probably have to put a new supply in it also, so… doesn’t sound like a rocket science type of decision…
I had a ‘pointer’ on my machine about two weeks and it came off (with a little help), but when I upgrade I might try one of the tubes that have an integrated factory set led/beam combiner. Mine always had to be adjusted, figured I did better without it…
Good luck.
on the upgrade, which is probably a ways off… one addition tip to keep in mind is that if your using gold over glass mirrors I found that they won’t hold up to bigger tube with higher power. I went to gold over SI without problem. you should be able to tell by looking at the back of the mirror as it looks like glass.
I spotted a post someplace where a few PVC parts were used to enclose the longer tube. (flange, pipe, cap) I’m not worried about it getting smacked into, so I think that’ll work for me. If the power supply can drive a larger tube, great, I’ll do it. If not, I’ll have to stick with another 60… which will probably still be better than the “60” that came with the machine.
I just upgraded my mirrors to si/gold as one of the stock mirrors was already damaged.
Once again, thanks for all the input!
I don’t know anyone that makes power supplies and one fits all or a low power to drive a high power circuit.
I have a 44 watt tube, but the supply is a 60 watt, so I could move up without a supply change. Check your power supply, it will tell you what it will support.
How your laser functions is highly dependent on how the power supply is functioning. Lps are low cost compared to tubes.
Good luck
I was holding onto the extremely small sliver of hope that my power supply would be rated for more, but it’s not. lol
For the hell of it, I contacted OMTech. No real help, just said that if it appears to be working normally, I can leave it. Considering the draw is 20% over the recommended max, I’m not thrilled with that reply, especially since my warranty is about to expire.
Just checked the controller, says I have ~136 hours on the tube. Seems way too short a time to start failing.
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