I am in NE Scotland, just south of Aberdeen.
Just to clarify I have the Cohesion3D Laserboard, purchased days ago.
I get full power, but when I set up layers in Lightburn to vary the power the mA meter always shows 10mA, even if I set at power level of 3%.
I confirm the issue using the Cohesion3D LCD test fire utility, where no matter what I set (full, half, 1/4, low etc…) I always get 10mA output on the mA meter, and my cuts are always the same depth.
The K40 test button and pot are working, I can vary the max power on the pot and the depth of cut varies.
Some testing with the scope.
It’s a triangular shaped PWM being applied to ‘L’ (probably started life as square wave PWM though with the rising edge charging something).
Here are some photos below using the Cohesion3D LCD TEST FIRE utility, in order from FULL ON through to OFF. You can see the PWM in action (mark space ratio varying), and it can be confirmed when a DC voltmeter is put on it, the rms voltage does vary with power.
What is NOT good from an electronics standpoint is that the voltage of the waveform is varying also with the mark space ratio. There is a PWM signal present and therefore it should be doing something.
As the cut-off is <=0.3V (on) and >=3V (off) the waveform is in that area sometimes…but look closer it needs 3vdc or greater to switch off but the overall waveform is mostly well below 3vdc …so no much wonder I get 10mA all the time. Saying that, from my understanding the input on the K40 PSU is an opto diode, so it’s about current, not voltage…so all may be well…I’m not convinced by the 0.3/3.0 spec.
While I wait on Cohesion, it’s time to play by building an interface circuit to clean things up…
EDIT: Confirmed. When I disconnect the L input and put a 1k up to 5vdc externally the PWM output from the Cohesion3D board is much cleaner and the voltages higher (3vdc attained). Looks like the Cohesion3D board is not interfacing properly to the L input on the psu.
So, I wired it all back up and simply fitted a 1k resistor across L and the 5v to the pot (pull up) and I can now vary the power, just need to play with the resistor value to get varyance at all power levels.
What the resistor is doing is bringing the PWM waveform back crossing 3vdc as per the spec.
Other info, 24vdc supply out on the same 4-way header = 20vdc.
DC to pot = 5vdc
Pics before mod, full ‘on’ through to full ‘off’:-