if I do LPS fire test we are at 18 but, if I set lightburn power 100% it goes out 15 but, why?
Disconnect the wire going to the “L” pin on the LPS and then ground it.
Be careful the laser should fire!
What current does it read?
if I understand correctly I have disconnected L from lps and I have connected L to gnd lps, nothing happens the laser does not turn on
…to be clear with power on, configuration #3 you connected the L pin on the LPS to ground and the laser did not fire??
Not what I meant.
You connected and output to ground and may have damaged it!
More clear: Disconnect the wire going to the “L” pin and then ground the L pin on the LPS.
donkjr I did your test, I connected L to gnd, on the aperometer it marks 15 ma
Grounding “L” and pushing the test button on the LPS should give the same LPS current.
Since Lightburn and the grounded “L” give the same value Lightburn nor the PWM control is the problem. The difference has something to do with the LPS. 
You probably lost steps with grbl-LPC because you forgot to set the stepper current (MKS SBase does set the current by software):
-
$140, $141, $142 are X, Y, Z current (amps)
- Default is set to 0.0 A to avoid burning out your motors
- Your motors will likely stall if you don’t set these!
And you need to set the PWM config:
- $30 is max S-value for Laser-PWM (default 1000, must correspond with gcode generator)
- $31 is min. S-value (default 0)
- $32 is Laser Mode (should be set to 1)
- $33 is PWM frequency in Hz (start with 5000)
- $34 is PWM off value in % (usualy 0)
- $35 is PWM min value in % (usualy 0)
- $36 is PWM max value in % (default 100)
1 Like
Doesn’t the test above Ground “L” vs push the LPS test button eliminates the controller as part of the problem? There is a difference between the two with no controller hooked up?
@donkjr My message was not related to yours, it was related to an early post of marcy, where he told he lost steps with grbl-LPC and therefore switched to smoothieware.
Ah that makes sense…
cprezzi the firmware loaded is yours, the amps I put 0.60 all 2 axes, y axis motor k40 from 0.9, motor x axis NEMA 17 from 1.8, but here the biggest problem I do not understand why it does not supply me the 20 but from lightburn power 100
Can you check the gcode that lightburn is sending? What maximum S value is in there?
This value has to match the $30 setting.
Did you use the bed mosfet output connected to the L pin of the LPS and had a potentiometer on IN pin (or a bridge from IN to 5V)?
The IN pin is regulating the maximum power and the L pin is just switching the laser on and off quickly (PWM).
When the IN is connected to 5V and the L pin is grounded, all at the LPS, the output power will be the max the LPS is capable of outputting.
To summarize:
With the IN pin connected to 5V.
- Push laser button on LPS tube current = 18ma
- Ground the L pin the LPS tube current = 15ma
I do not know yet why there is a 3ma difference but:
I would say the max the supply can output is 18ma.
Where does the 20ma come from?
scheme n1 maximum power 8 ma
scheme n2 maximum power 20 ma, when the laser moves it stays on 3 but ruining the job
scheme n3 maximum power 15 ma
We need to stay with configuration 3.
Can you measure and tell me what the voltage on IN is in configuration 3
i measured between IN and GND, it comes out at 03.4 on the tester
It should be 5V isn’t it connected directly to the 5V pin?
Measure the 5V to ground.
if I measure between 5v and gnd it is zero, because I discovered that this psu does not have 24v, and it does not even have 5v