I have double checked that all 4 blue wires line up to 24v, g, 5v, and L. In fact, we can verify this because the 24V LEDs are wired into that 4 pin coming out of the LPS. On the board side, the red dot is wired to G and 5V and it works. Though I have since removed the red dot wires as they were just stuffed into that connector, not even crimped.
So it seems to be wired properly.
I posted this same thing on the cohesion3d forum, but have not gotten any replies.
@donkjr FYI, this was with the c3d board connected. And when I said it does or does not fire, I meant automatically. I found some new results - see below comment…
I just tested this again WITHOUT the DC in connected to the c3d - only the X and Y, endstop ribbon cable, and 4 pin 24, g, 5, L connected - same results.
Also, as suggested, I removed the L wire from the 4 pin and the laser does NOT fire automatically, when I connect it again, laser fires automatically.
Put the Nano back in - works normal. Powers on, laser does NOT fire unless I press the laser test button. HOWEVER, see below comment!
Here you can see the back side of the c3d labeled which pin is which, then showing the front side where the L wire is routed properly. The other 3 are going to the right pins on the LPS as well.
@donkjr I just hooked up the Nano board as it came stock, but removed the L pin from the plug at the LPS and it did NOT fire automatically. When I hit test fire laser, the laser DOES fire. Even when L is unplugged!
I then unplugged the entire 4 pin and powered up the laser. Didn’t fire automatically, but when I press test fire the laser fires!
I switched everything back over to the c3d board and powered on the laser, with the 4 pin connected, laser fires automatically. If I unplug the 4 pin at the LPS and power on, the laser does NOT fire automatically, but DOES fire by hitting the laser test button.
Faulty LPS??
Correct me if I am misunderstanding anything. Is the laser supposed to be able to fire if the rightmost pin is unplugged?
Best way to check for proper grounds? I removed the ground stud and sanded all the paint off then reinstalled the ground coming from AC in and the ground from the LPS. Anything else I can do or check?
Hang on … lots of info to break down…noodling this one … 
FYI: for the laser to fire the
The voltage on the IN pin determines how much power. (yours has a digital panel so the IN pin will be a PWM signal) but the average voltage still represents the power.
Can you explain how each of these are at ground?
Maybe I misunderstood that 4 pin connector, I thought the laser couldn’t fire at all if it wasn’t connected.
K+ is grounded by the laser enable switch
L is asserted to ground by the controller. In the C3D case the L is a pwm signal coming from the controller that is ground true.
The LV connector has the L signal in it so if it is not connected the laser will not fire from the controller. It can still fire from the test fire on the panel and the test sw down on the LPS.
Okay, so perhaps the Nano board is functioning properly then.
The c3d may be another story…
I’ll let you digest everything I posted and see if it makes sense to you. I’m at a loss…
I think these symptoms nets out to the following:
Proper operation:
With the LV connector unplugged or the L pin disconnected the “test fire” button will fire the laser if it is enabled with the “Laser Switch” being asserted.
This is because in your machine the P&G is jumpered and the control panel controls the state of the K- to K+ connection. In the digital panel configuration, the L (in the LVPS connector) is not connected to the panel. The panel asserts A PWM signal on the IN pin to fire the laser when the test-fire is pushed.
Don's Laser Things: Understanding the K40 Digital Control Panel???
Improper operation:
Only when the C3d is installed: the machine turns on the laser at power-up. There is never a case where the laser should come on at power-up.
Symptom with Laserboard installed:
When the L pin on the LV connector is pulled
OR;
when the LV connector is not plugged in
… the laser is NOT turned on at power-up.
Conclusion:
The C3D is holding the L pin on the LV connector low (gnd).
Gosh, this problem feels like de-ja-vu but I cannot find a thread on here that looks like this.
Test:
These are more sanity checks…
Measure the voltage [to ground] on the LaserFire pin of the LaserBoard with the power on with these conditions.
---- Measure Voltage on Laserfire ----
Do this one with power on
|Ref#|LV connector on C3D* |Volts on LaserFire @ C3D|
| — | — | — |—|
|M1|Plugged in |??|
|M2|Not plugged in|??|
*with the L pin inserted in the connector
Continuity test
With the power off
AND
LV connector plugged into the LaserBoard
AND
LV connector plugged into the LPS
Measure continuity (ohms) between the grounds on these three things:
LPS-Laserboard =
LPS-Laserboard LVPS =
LaserBoard - Laserboard LVPS =
ALSO:
Can you post the ## Laser module configuration portion of your configuration file.
@raykholo
It’s been a while and I could not find the correct schematics for this board. I am just trying to see how the Laserfire pin is being driven in this board configuration. Can you point me to the schematics??
Just so I am clear… are these conditions for ref # 1 and 2, or are these meant to be conditions for additional tests?
To ensure I do these tests correctly, can you clarify the connection you are looking for in the last 2 tests?
LPS-Laserboard LVPS = [the ground on the LPS and the ground on the low voltage supply you are using to power the Laserboard]
LaserBoard - Laserboard LVPS = [the ground on the Laserboard and the ground on the low voltage supply you are using to power the Laserboard]
This is essentially checking that all the grounds are connected together.
These are conditions for the grounding tests.
The other tests are voltages on Laserfire.
I edited the post to make it more clear.
Ah, I had a feeling this was what you are looking for. See the photo, which is the power supply C3D supplied to be used with the board. Not sure how I can test ground on this…
MMM did not know that was the type of supply.
Plug it the ac and and measure the voltage on the dc connector from inner pin to ground just to be sure there is a ground.
Plug it into the Laserboard and then check (with power off) the continuity between any ground on the laserboard and the LPS ground.
Before I do anything wrong, is this where you are saying to measure voltage? From the DC in - G on the LV connector?
I meant before you plug it in but that will work. Do not short out those pins.
Sorry for my confusion, how would I measure voltage prior to plugging it in?
