K40 Laser cutter wont fire on jobs. Still fires on panel/psu test.. Gives Message "L" - No Laser Signal

Lasers
62

Tell be about it :sob: yeah will get it sent back & I’ve got a ‘better’ one arriving tomorrow.

63

Yes I mean short the two pins together briefly with a wire.

What … ( hair pulling) … are you saying that the jumper did not cause the laser to fire???

Those two pins are connected together then you push the test button. I can see the two pink wires connected to those pins??
Do those wires go to the laser test button?
Is your jumper really a short?

64

Good question @donkjr. It just occurred to me that if the “laser enable switch” and “test fire” button wires are swapped the machine might have the symptoms in this thread.

(i.e. The laser enable would be wired to the test button so the laser would only be enabled when the test fire button is pressed. That is also something that is relatively easy to wire wrong since all of the wires would go somewhere and the machine would pass a test firing.)

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65

Certainly puts more sanity into this situation.

When the “laser switch” is ON the L signal P2-4 which is internally connected to the L signal on P1-1, would be held low.
If the “Laser Test” button is not pushed the laser will not be enabled because the P-G (P2-5,6) circuit is not closed.

When a job is Run :

  • “Laser Switch” ON … L goes low.
  • The test button is not pushed so laser is never enabled
  • Job runs with not laser

If the above is true this situation should be true

  • If you run a job with the Laser Switch ON
  • When you push the “Laser Test” PB the laser will come on only while the button is pushed
  • The laser will only image black lines while the “Test Button” is pushed.
2 Likes
66

Having a hectic few days so just been able to get back to this, thanks so much for the continued support.

  • The jumper did not cause the laser to fire, it’s a decent size about 10 inches.
  • The wires actually go to the laser enable switch :exploding_head:
  • Also the new DVM seems to work fine (see 2nd pic)
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  • I’ve just tested your 2nd situation from your latest reply, it was true. Ran a job with Laser Switch ON … I pushed the Laser Test during, and the laser fired only when I pressed it … It didn’t seem to leave any black lines though, I knew it was firing as per the tube area & top right corner lighting up when I pressed the “Test Button”. Strange, as the laser makes dots anywhere in the cutting area while static.
67

@crowland186 It does look like your wires for the “laser Enable Switch” and “Test Button” are going to the wrong switches respectively. I believe switching the pink and brown (not sure of the actual color) wires will fix the issue you are having with your laser. Pics below

A potential fun experiment you can do before you changing the wiring:
It would be interesting to have you turn the “Laser Enable Switch” OFF and hold the “Test Button” down when you run a job. The laser should fire under control of the controller board if you do that.

Below are your pictures with some wiring annotations.

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Finally the next image is a version of Don’s wiring picture from above with the relevant items boxed as a cross check.

laser_wiring_dons
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69

Bang you got it! Nice eye @Scorch!

Wow! did we get dizzy…

This suggested to me they were wired backward …

I interpreted this as “it’s wired correctly” and in sequence, it clearly says they aren’t!

This is why we should always ## the questions and answers :).

@crowland186 I would swap the wires and I’ll bet we are done.

4 Likes
70

Damn, thanks for spotting that & the annotations! Annoying how some of the wires can blatantly be in the wrong positions. I Switched the Pinks & Browns (maroon), and still same result :tired_face:

See the Vid I attach in my reply to Don

71

Sorry, will be sure to # future questions & answers.

Was all excited ready for the moment of truth but it seems to be doing the same thing :tired_face:

  1. I’m wondering whether as the head moves, the alignment could become slightly ‘off’? I examined the inside of the laser head and couldn’t see any obvious etch marks.
  2. The laser now DOES fire on a job (see the vid), but without seeming to leave any mark.
  3. The POT still seems to work backwards, with the mA dial moving less and less as I increase the power, while at 100% power the laser doesn’t seem to make a mark at all.

What a strange situation this is, thanks for taking interest!

72

So the original problem is fixed with the wire swap right?

73

It seems it as the laser is firing (laser tube area lighting up) but still no markings from the laser in the work surface

74

Ok so have you done an alignment and checked the beam at each mirror?

75

Yes, I adjusted the mirrors 1 by 1 following this guide: https://youtu.be/AN441sgshE4

76

what does the beam look like before and after the head.
Do this using the test fire button.

Post pictures

1 Like
77

Hi Don, here’s some pics:

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Wasn’t sure what you meant by the beam “after the head”

The beam hits mirror 3 pretty central but I’ve got some 2mm nuts which could increase the height if needed. With mirror 2 I can’t move it anymore to the right on the plane it can be moved on.

Hope it’s not too confusing

78

Ok, so the beam makes it to the head and then doesn’t come out the bottom? What is probably happening is that the beam is hitting the inside of the air assist nozzle. Because of the crappy mirror mounts in these machines you can’t assume the beam is coming down perpendicular to the lens after the 3rd mirror.

You really need to try and get the beam more centered on the mirrors. Start from the first mirror. It may require you to shim one end of the tube or the mirror mount itself.

To check if the beam is exiting the bottom of the air assist nozzle put a piece of tape over the hole and do a test fire. Put a small mirror under the nozzle and shine a flashlight through the mirror hole and look to see if the beam has marked the tape. If not, rotate the nozzle a bit in either direction and repeat to see if you can recover the beam. Besure to remove the mirror before each test fire.

2 Likes
79

The beam reaches the head and comes out of the bottom when the head is not moving, and I press the test laser. The problem is that the beam doesn’t seem to come out of the head when it’s moving so the laser doesn’t appear to fire during jobs.

Okay I see, so do you think it may be hitting the head when moving, but going through fine when not moving?

I’ll go over all the mirrors and get the beam central, see if this fixes the issue.

Okay I’ll test this out and post the result, thanks for the advice

1 Like
80

If it doesn’t exit the nozzle during movement I have to wonder whether something is loose.

Is the spring holding the mirror onto the laser head secure? It’s not obvious to me from the picture whether the mirror can move.

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81

Usually then the beam doesn’t exit when moving its cause the beam is not parallel to the carriage. I.e. going uphill or downhill.

Test fire with the head positioned at the extremes and verify that it makes it through the objective lense in all 4 corners and the middle.

As Ned suggested the beam needs more central adjustment then see if it exits the head all all the extremes.

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82

@mcdanlj I think you are on to something, that mirror looks like an Instagram star on a cliff (about to fall off).

mirror_fall

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