Tube Doesn't Appear to be firing. PSU and electronics seam fine?

[Alasdair Leighton-Crawford]

Firstly thanks so much to everyone's feedback regarding fixing the broken inlet tube. I re-attached it last night, and it seems to be holding strong...

Now having hooked up the laser tube and got all the electronics working, firing it up seems unable to mark paper - either using the below g-code or by pushing the test button on the PSU.

S20
G91
G1 X10 F500
G0 X-10

I've checked through all the electronics. All the lights are coming on the laser tube PSU( Laser Power and WP) and I hear a high voltage firing sound when I instruct a cut, but I don't see any marks on the masking tape.

What am I doing wrong? Is there positive terminal correctly attached? I carefully followed the instructions to insulate it tube.

Thanks again,

Best wishes,

Alasdair

[Stefan Hechenberger]

Alasdair, have you tried more power? S20 is likely still in the
pre-ionization range. What happens when you use S80. S255 means 100% btw.

--
Stefan Hechenberger
studio: Nortd Labs - labs.nortd.com
resident: F.A.T. Lab - fffff.at
project: Lasersaur - labs.nortd.com/lasersaur

[Alasdair Leighton-Crawford]

Hi Stefan,

Thanks, I've just tried you above suggestions with sadly no positive outcomes... What's the next step, Is my tube faulty or are there any other tests I can do? I'm pretty sure that the PSU is working fine as when I send a cut signal, the laser led goes a more intense red indicating it is cutting - the electricity is pulsing to the device. Apart from that I not sure what else there is to do... :0(

Thanks again,

A

[Stefan Hechenberger]

Alasdair before you proceed you may want to verify that you are actually
getting 5V on the laser PWM line when you run the laser at full power
(S255). Then also check if the laser disable line is low.

Next measure the current that flows through the tube. You can do this by
placing an amp-meter in series at the low voltage side of the tube
(typically the blue wire, on the side where the beam exits).

You should be getting around 28 mA at 100% (5V on TH/pwm pin). If this
differs you can adjust this via the PSU's trim pot:
http://www.flickr.com/photos/stfnix/6987014326

Make sure to use an isolated screw driver when adjusting the trim pot
and generally be overly careful when working on the Laser PSU.

--
Stefan Hechenberger
studio: Nortd Labs - labs.nortd.com
resident: F.A.T. Lab - fffff.at
project: Lasersaur - labs.nortd.com/lasersaur

[Alasdair Leighton-Crawford]

Stefan,

Thank you again. No luck despite your suggestions. See ** below for my outcomes.

Alasdair before you proceed you may want to verify that you are actually
getting 5V on the laser PWM line when you run the laser at full power
(S255). Then also check if the laser disable line is low.

** PWM Pin on Shield - S255 - Constant 4.5V
** DIS Pin on Shield - s255 - Contant 0.02mV.

Next measure the current that flows through the tube. You can do this by
placing an amp-meter in series at the low voltage side of the tube
(typically the blue wire, on the side where the beam exits).

** Connected in series, no reading. This is probably not good.

You should be getting around 28 mA at 100% (5V on TH/pwm pin). If this
differs you can adjust this via the PSU's trim pot:
http://www.flickr.com/photos/stfnix/6987014326

** PWM Pin on Shield -  S255 - 76.6mA?

 
Make sure to use an isolated screw driver when adjusting the trim pot
and generally be overly careful when working on the Laser PSU.

** I have a Coletech 40W PSU (40W tube), I had a look at the box, but I can't see any way of adjusting the voltage from the outside other than opening it up, which is a potential lethal hazard…

I'm still fairly convinced that the PSU is working fine - to back this up, all the lights are shining correctly, the laser light fires up bright red on cutting and at the same time I have seen a short sparking on the postive - HV end of the tube around the internal ring (which may or may not be a good sign) but no sign of the laser marking on the output end.  :0(

Where do I go from here? Thanks, I'm just keen to get going with using the machine as everything else to date is running flawlessly!

Best wishes, Alasdair

[Frank Kolkman]

Hi alasdair,

Did you ever resolve your problem?
I've seem to have run into the same kind of trouble, however a few hours ago I've been happily cutting away.

Already traced all the wires seem ok measure ok, also another indicator is that the test button doesn't yield a result other than turning the red led one the coletech PSU a little brighter.

As far as I can tell no leaks or cracks in the tube but will have a better look at it Friday. Will also strip the insulation (with PSU disconnected) to check connections, however like I said I've been enjoying the having a running laser cutter life for a while now without much trouble. It can't be that it deteriorates instantly right?

Cheers Frank