I’ll tie all of the grounds together too, because yes, I did disconnect one of the grounds from the PSU, I didn’t think it was completely necessary though since there are multiple grounds on the PSU. So when I checked with my multimeter, the rightmost ground on the PSU, does in fact go to my 24V and my 5V power supply. (Not a direct connection, but because of the other grounds all tied together on the different power supplies)
That blue wire goes to the negative end of the Laser
It’s best to insure grounds are not daisy chained or looped in any way and all return to a common point. Just because a ground has continuity doesn’t mean it’s a good ground. Especially in systems with low voltage controls of High Voltages. Grounds currents should be viewed just like you would high speed signals. The return from the load should be as short and direct as possible to it’s source.
Btw unstable power is often caused by poor ground design.
Of course this is not what’s stopping your laser from firing.
I’m noodling our next move…
Thank you so much for all of your help! I honestly was out of motivation the past few days from these problems. I’ll rewire the ground so that it’s more direct, but it doesn’t seem like the problem and I agree there. I’m waiting for the replacement that the seller sent (should be in in a week), but I’d like to assume something else is the problem and diagnose based on that logic so that I’ve exhausted all other options by the time the new tube comes in.
One thing I was thinking was the possibility of microfractures from using the laser in the cold (daily the temps been around 25-35 degrees F), and I’ve been blowing the water out of the laser tube with a low psi of air (5-10psi) before the temp drops below 32 or after I stop cutting with the laser. My thinking was that maybe microfractures (that I can’t see) from blowing air with the compressor, have broken the tube.
A few days before I completely lost power, the laser slowly lost power, I would cut plywood at 7ma, then the next day 10ma, then it took 13 and a few days later it wouldn’t give any power. Could this be CO2 slowly escaping the tube from microfractures?
We solve problems here
sometimes it takes a while but we will eventually fix it!
Usually, when we get down dead-end paths the following is at play:
- We made bad assumption(s) that caused us to misread the problem.
- There is something unusual about the machine that is not made apparent through remote communications. Pictures are important.
- There are multiple problems at play.
As I was thinking about this last night … consider this dialog.
Given above:
If that blue wire goes to the negative side of the laser, how is the ma meter wired into the laser’s cathode current?
THINKING OUT LOUD of POSSIBILITIES
- Not likely: The LPS is bad; unless the new LPS is bad or we damaged it.
- Most Likely: The tube is bad, but there are some hints that it may not be:
– The LPS will usually ARC if there is a bad tube (no load)
– We had both a bad tube and LPS, less likely ? - Likely: There is something wrong with the LPS control signals stopping it from outputting HV?
Assumption: When using the red LPS test button the LPS should fire irrespective of the control signals?
I looked at the LPS schematics again this AM to verify that the laser should fire using only the test button down on the LPS. Looks like its possible that if the IN pin is not between 1 and 5V it would not fire.
Next steps:
A. Verify how the ammeter is wired. I am guessing you added it, noticing a marker outlining its placement on the control panel. One of the symptoms that lead us to conclude it was a bad LPS is the 0 current reading on the milliampmeter. If that is a bad reading then it could lead us astray.
B. Measure the voltage on the IN pin of the LPS relative to ground. It should be between 0 and 5V and it should change with the digital settings on the panel.
If the voltage is adjustable on IN then set the panel’s power setting to 100% and push the red test button on LPS.
Let us know what you found
I’m still noodling …and challenging all my assumptions.
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Requesting a random piece of information:
- how did you attach the Anode and cathode when you replaced the LPS? Please post pictures of each.
Sorry for the delayed response and thank you for all of the help!
To clear up any confusion around my ammeter, my blue negative laser wire goes connects to the ammeter and then to the power supply. That works perfectly fine, I was cutting for about a week and the the ammeter was working great.
Hmm, I like that theory about the IN pin being the problem possible, but changing power supplies and getting the same problem makes me think that that can’t be the problem.
Will that pin only read voltage when I hit the laser test fire button?
I soldered the red wire going to the laser and filled it with a crap ton of silicon when I put the new PSU in. To replace the blue end from the laser I just plugged it into the PSU (this is the 4 prong plug on the left of my PSU). I tried to do as little soldering as possible because I didn’t want more problems than I already have.
I’ll post some pictures later tomorrow when I have time
The IN voltage comes from the digital control panel. It is a PWM signal proportional to the digital setting on the panel. It was not replaced with the new supply making it a candidate.
Should read any time there is the power to the control panel.
You soldered the wire on the pin of the tube?? If so, not a good idea the heat can crack the tube. That wire can simply be wound around the post. Check for cracks.
Make sure this is a good connection? The laser will not fire with the cathode un-grounded.