Hi all, new here and have a very strange problem indeed.
I have a 50W blue & white laser which until recently was working fine, then noises happened from the control box area and all of a sudden I can no longer fill/scan or cut, line work is still fine.
I have done all of the most obvious things, cleaning, alignment ect and have not reset anything that I know of.
I have have attached a picture but it is poor due to how I took it but with what I hope is enough description and clarity that someone will know what the problem is straight off.
I will be replacing the PSU when it arrives regardless as I believe it could be part of the problem, but all input is most welcome as there is more a foot here than I care to or want to know about but most of all I need help please and need it asap thank you for taking the time to read.
Regards Bruce
What kind of noises are you hearing, and are you able to identify more precisely if the noises are coming from the controller(what is the controller model?) , or from the high voltage PSU? If you are hearing a crackling noise from the PSU then that would account for the lower power output for the cutting, and possibly also what looks like a malfunctioning of the handling of the laser enable signal. Seems like you have already diagnosed a fault in the PSU since you have ordered another?
Underneath the top ‘Fred’, what is that filled shape supposed to look like? Is that a filled decorated ‘B’ under the lower red arrow?
The tube is generally considered the ORU (Optimum Replaceable Unit). However how they use components that don’t meet specifications it also an issue and can affect something like the hv lps.
Check the TEM0 state of the output of the tube, before you replace the lps and after to see if the resonance is the proper state.
My China Blue went south real fast, but it’s the tube, not the lps…
jkwilborn and NicholasL thanks for the replies really appreciate it.
ok, The noises where definitely High Voltage arching I have also noticed that the very inner tube glass looks like it has gone a little pinkish in color also, it may have always looked that way but I have only just noticed it since the noise so I am not sure what that means either.
NicholasL, Ruida 6442G I presume as it has no numbers and Lightburn identifies it as RDC644XG and yes that square of lines between the Fred and the bottom ‘A’ is the word Fred as fill that is what it produced and the other fill to the right of the ‘A’ is the letter ‘B’ as fill in the same style as the ‘A’ on the far left.
Also if the laser power supply was faulty that could possibly explain the framing and travel lines being present because it is not switching properly correct?, I really hope so as that bit has been stressing me as I have been thinking it might have zapped the controller as well and I really hope not.
The noise definitely came from the Laser HV PSU.
jkwilborn, I never heard of TEM00 state until now thanks, I’m still not really sure what it means but I do know looking at the end of the tube (off and out of the machine) the end is roughly the same solid colour and when I fired a dot last it was round and consistent, I hope it means one of them two things otherwise I really don’t know what TEM00 means and certainly going to have to read some more on that.
Does the pinkish color on the very inner tube mean it is also failing? or is that normal?
Do these Laser PSU’s just fail unexpectedly or is it bought on by other parts failing?
I ordered another Laser PSU because of the noise ect and figured even if it was not that it was there just incase but I was/am really not sure about all the lines and fill as it is not good knowing the laser is firing while it is doing a frame ect not to mention all the lines on your work and loss of power.
Any If you need anymore info fire away, let me know and thank you very much for your input.
Regards B
As a general rule the way dc excited lasers work, is the lps increases voltage until the nitrogen (I think) starts to conduct, which starts the lasing process. If this arced internally to the lps, then it’s the lps.
Usually what an arc means is that the tube has failed and the voltage has gotten too high for the surrounding insulation. I’d look for where this arc occurred and see if it is at a weak point, such as a connection point. If it goes through some point, it usually leaves a hole where it went.
I think an lps is lower cost and if you are sure that you are getting a TEM0 state… then the tube would be OK… however if the lps or tube is bad it’s generally consistent.
You want a TEM00 state or the laser won’t really work well and will be difficult to align.
Don’t know what mine looks like now, but I noticed a loss of power and when I did the test, mine was… tube is toast… Have a new one here now.
I agree that a failing tube can stress the power source and trigger arcing - It would be interesting to know more about this, and possibly how to test a suspected faulty tube without risking damage to a new LPS? If the tube is only partially OK it must represent enough of an electrical load to prevent the open circuit protection built in to the LPS from kicking in.
I’m also curious… have you ever noticed with some tubes that when fed a low power% (e.g. when alignment testing) they can have a slight donut spot?..but that pattern disappears at higher power… you wouldn’t want to discard a tube because it failed the TEM test if your test was at low power.
jlwilborn, thanks for the explanation on the TEM00 I now know just a little more about lasers or when it completely sinks in I will, the arching was in at the control box so I assume it is safe to say that that is where the problem arose I did look as thoroughly as I could but will look more when I remove it.
I notice on your test dot the blank area on the bottom part of the cross must be what you are referring to as the dot actually looks like it is 2 halves.
I have noticed on my laser that the dots have been fairly consistant and once I dropped to under 15% power the tube would not fire and had to stop using masking tape as nearly everytime the tape would just burst into flame and my dots very quickly become toast.
I checked the Red wire for breaches but was unable to find any and the plug a little sloppy I feel was secure enough to make good connection and the return wire (blackish purple) is just one wire but I will be installing an amp meter into that very soon.
Come to think of it when I was checking the alignment it was a little harder than normal to get the dot I had to hit the pulse button a few times to get what would have normally only been one push of the pulse button.
NicholasL, I have read somewhere a couple of times during the pursuit of answers that the Laser PSU can withstand very brief periods of arching without damage but I am not sure I would like to try it and I cannot remember where I read it now to validate it so it is possibly one thing I would not like to put to the test.
Anyway thanks very much for your input it has put me a little at ease as I am almost satisfied that it is the PSU as to how and why it failed I have no idea, will post again when I do the power supply replacement and let you know how it turned out.
Regards B
My understanding is the tube is not getting enough energy for it to lase. I’ve been told this is bad for a dc excited tube… but I’m no physicist… If it’s not running in TEM0 there is more damage to the existing gas mixture… So you don’t want to run it so low you are not in a TEM0 mode.
Except for me… I’ve really beat up my tube as it’s going south… nothing to lose…
There is a resistance (load) test I’ve seen… about 1:43 into the video…
I have a voltmeter in mine, so I can watch it… Don’t know what it will buy me… but I’ve been watching it… Cutting at 90% power it runs about 13kV at just under 20mA for a 44W tube…
I figured at 13kV at 10mA would be ~1.3mOhm, so I think it would get warm, with about 130W of power to dissipate.
Probably not for the faint of
@prottac you can set your pulse duration and power on the machines console… lower it for a better look at the beam…
I cut targets to use for this… these are good for m1 and m2…
@jkwilborn, Thanks for the additional information and further explanation I think I see it now, your dot to me is missing a section below the cross and to the right and it sort of also looks like it is 2 halves resting against each other at the top with the biggest half on the right hand side, I could be wrong and my eyes way out but it would be enough to indicate that something was not quite right and would need further investigation, I also like your targets you don’t mind if I copy them do you, what are you making them out of please?
@NicholasL, well when I install the new power supply if the tube decides it is going to fail and does then that will be a clear indication that the arching is a sign of an intending to fail laser tube. I hope not.
I must also point out that the wire connections on the laser tube are screws not the normal wrap around tungsten poles so I am confident that I could rule out a possible weak link at the connections on the tube its self.
good thanks, yeh the paper does look a little thicker almost like blotting paper, as soon as i’m up and running again be definitley making some, really good idea no idea why I didn’t think of it myself, to busy stuffing around with masking tape I think.
Anyway thanks for the info really good of yourself and NicholasL
Hey all,
I have replaced the power supply and done a small test and it cut and filled nicely so I would guess that the power supply was the problem, how it failed I do not know but it is still the same tube doing the work.
So if you ever hear a loud arching sound coming from the control box side and you can nail the noise down to the power supply then that is what is more than likely the problem, or a good starting point.
Regards B
