No, you were right on about the power supply. Many people don’t check these. I’m tickled you did.
My 50 watt came with a 60 watt lps. It would deliver about 26mA and my tube was documented at 21mA max. So anytime I fired it before the adjustment it got 26mA, shoved down it…
Some controllers (possibly not yours) allow for limiting power, such that 100% power in the LightBurn job will scale to the controller set limit - ensuring that the current draw at 100% is well within your tube specifications for maximum life.
If you can - this is the best place to make an adjustment, as it allows you easily increase that ceiling if you have a challenging job, and when the tube starts to get tired you can creep that limit up (and unlike a trim pot you’ll have numbers for your service records).
I’m mainly adding this comment as we prefer to discourage people from poking around high voltage power supplies with screwdrivers, the screwdrivers that ship in the toolbox with some lasers are not properly insulated and even with the power off the HV power supply unit can be holding a nasty charge.
The controller has nothing to do with the current draw, it’s completely the lps that sets the current. The controller only turns the lasers lps on and off.
The only limit in the Ruida is percentage power.
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You should adjust an hv lps for whatever you determine max current to be, since when it ‘lases’ it will draw the max current of the lps.
Make sense?
78% of all electrocutions, in the USA, occur in the home with the mains voltages.
Be respectful, but needless fear will injure/kill you.
Hmm…as I understand it there is a certainly a direct correlation between controller and current draw - because if you limit the power setting at the Ruida to 80%, the PWM output pin will be limited on it’s duty cycle to 80%, which in turn directly governs the ability of the LPS to supply constant voltage to the tube, so even if the potential voltage available at the power supply is not trimmed and set at max - the effective current draw of the tube will still be proportionally less resulting in a cooler tube, and longer tube life.
Hi Thanks for the cautionary advice of course I did not use the chinese screwdriver which came with the machine I did not use that at all… those are for fun or I don’t know for what surely not for work. I used a properly insulated one. What was difficult is to find that little pesky hole on the PowerSupply it is really hidden no sign or anything and it is in a place where you cannot turn it …so first I had to unscrew some screws that fastened the power supply and change that potentiometer like that it was a nice view surely but I did the job and reassembled the whole thing and it works well since than (about half year) I don’t know how long my tube will last some say years other say some month…let’s see (anyway I would like to have a stronger one something in the 80W range would be great
Yeah, I’m not following Jack’s comment either. I have a 90w Chinese laser with a reci tube and the reci website states the actual maximum ‘working’ mA is 24mA for my tube, s.I adjusted my psu down as you did, to set the limit when using 100% power in Lightburn. Curios to see if there’s an issue I’m not aware of.
Yep
What is crazy s that there is so little reliable information about this whole story. The documentation what came with my chinese laser is a joke really I cannot describe it anyhow else. Not just chinglish but absolutely unusable. There is a big sticker on my laser big yellow and black stripes and big bold text about safety full of glaring english language mistakes very funny really even goggle translate would be better…I show it my friends and we laugh at it together 
(although english is not our native tongue it is so bad everyone can see it…)
Obviously I’m not making sense… let me try and clarify…
I think you are all familiar with the controlling pwm signal.
It’s digital, when it goes high the laser turns on when it goes low the laser turns off.
There is no 50% level on that pwm signal, it’s on or off.
Therefore the laser is on 100% when it’s on, using 100% of what the supply can produce.
At 10% power, it is lasing 100% 10% of the time.
This should explain clarify why the lps should be set to a max value related to the tube…
Make sense?
Analog meters only display the rms value of what they are reading.
Power control is an illusion based on power/time.
There is really no power control with a laser, only speed.
The probable key to all of this longevity stuff is how well can you get rid of the heat…
OoooK You might be right…but I heard from many places that you CAN overdrive your tube if you put too much Amp to it…you than say it is just not true??? Heat management is of course a different topic…I still use the bucket of water + ice method but might go for an industrial cooler sooner or later. As the temperature goes what I know is that it should not be hotter than normeal room temperature which is about 21-23C Thanks
I think you missed what I stated, or stated it poorly.
An hv excited co2 is on or off.
What limits the ‘on’ current is the lps.
Thought it was 26mA, but my notes indicate 28mA max on the 60 watt lps.
My lps would deliver around 28mA if I let it. I test at 50% power and I get an rms 14mA. Twice that is 28mA, so the supply is probably capable of supplying 28mA to the tube. I don’t want more than 21mA.
The only way to limit this is to turn down the lps, as you did, so it’s limit is within the current limit for your tube.
If the supply is set to your max limit, when it lases, it’s current is limited by the lps.
I think that’s what this is about. When stuff gets warm it’s lifetime suffers. Many things change over just time, but heat accelerates everything… getting that heat ‘away’ is crucial.
Take care
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