Lasersaur upgrade

6 minute read

note: this post is linked to this issue, feel welcome to contribute.
I’ll need some help on these one

Stranger things happened with the laser.


Like, it cut better at 40% power than at 100%.
Since, I tried everything.

  • I cleaned everything, optics, bearings, etc…
  • I recalibrate optics more than a couple of times.
  • I changed mirrors and the lens.
  • I changed the power supply (which burned).
  • I updated the firmware and software.
  • I checked the TTL control signal with oscilloscope.
  • I replaced the honeycomb bed (it was dead, not related to the 40% thing.)
  • I finally installed a manual firing solution with manual power control (which give an awesome feeling ^^, pew pew pew )


  • And I finally bought a laser power probe.

Probing the laser tube for power issue

I had a good idea why we didn’t get full power from the tube. I is kind of old now, more than 3 years old, but I was expected something more progressive and I felt strange this behavior.
And of course, I was hopping not to have to buy a new tube which is quite expensive.

Anyway, just to be sure and better understand what’s happening under the hood.
I bought a probe. (expensive too)
It look like a cooking thermometer.


Ok then, I started to probe some shit from it.
For a 100W tube, the beam have to burn the black end for 15sec exactly.
I prepared a table and checked the power related to the ampere sent by the PSU. 3>25mA.

mA Power Readings 09/06/2018
3 12% 0%
4 16% 4%
5 20% 9%
8 32% 28%
10 40% 44%
11 44% 43%
12 48% 43%
13 52% 41%
14 56% 40%
16 64% 40%
18 72% 38%
20 80% 34%
25 100% 28%

So, the red line (readings) should be close to the blue one (theory)



Time for a reality check.

The laser is dead.


Replacing the tube

  • be sure to unplug everything. You are alone in this, if you die from electrocution.
  • Unmount panels.
  • Check wiring of manual firing solution, take picture to not forget. ;)
  • Unplug everything linked to HT power supply.
  • transfer to new connecteur with 5V on the left (not the same PSU)
1 2 3 4 5 6
symbole type description
5V Output Power output of 5V, as reference for linear pot. (manual fire : power adjust)
TH Input Signal Laser Control Switch , High Level(>=3V) : laser ON :eight_spoked_asterisk: ,Low Level(<=0.3V) : laser OFF :no_entry:
TL Input Signal Laser Control Switch , High Level(>=3V) : laser OFF :no_entry: ,Low Level(<=0.3V) : laser ON :eight_spoked_asterisk:
WP Input Signal Cooling safety Switch , High Level(>=3V) : laser OFF :no_entry: ,Low Level(<=0.3V) : laser ON :eight_spoked_asterisk:
G Signal Ground The frame must be connected with laser machine’s enclosure and ground properly.
IN Input Signal Max Laser Power control, can use 0-5V Analog Signal Control


  • Disconnect cable from tube. Red on the left, White on the right.
  • Emptying the cooling system, there is a drain on the bottom back side of the chiller. (there is more than 7 liter, be prepared)
  • Disconnect water Outlet first. Water will continue to get out trough inlet. (+ side)
    It's best to heat the tube, it will "ramolir" and will be easy to get it off.
  • when no water left. Disconnect the inlet.
  • take out the tube
  • put the new one in place, put ONE layer of the rubber thingy tape each side.
    (= some comfort and same thickness both side)
  • Adjust what is loose. And fix the tube with one set of ziptie.
    Just enough to secure it during replacing water tubing on inlet and outlet.
    Inlet MUST be bottom, Outlet MUST be on top
    To naturally help the air bubble to stay out of the cooling system.


  • Install the power supply.


  • Fill up the cooler with distilled water. One bottle of 5 liter is good for now.
  • Power on the chiller. Check for air bubble in the tube. If there is. Turn off then on again the chiller, it usually get rid of the last bubble.
  • Secure the tube.
  • check again the level of water of the chiller.
    The level will drop since a part of the water went to the tube. Adjust level until the upper green limit. Just to be nicely full.

yeah, outlet of the chiller become inlet of the tube, outlet of the tube become inlet of the chiller. That right. +1 for who noticed the ziptie's color code ;)

  • connect HT white wire from tube (- pole) to the amp meter on the left pole.
  • connect the right pole (amp meter) to the HT power supply cable.
  • Test to fire the tube, after turning on the power for chiller and the laser PSU.

Check if the door is closed, it would trigger the safety and nothing will append. Same as the chiller if not powered on.

  • Adjust the PSU amp to 25mA as max power setting. For best lifespan. Over 27mA, the tube will have more power but will burn more quickly.


YEAH, it burn baby.

As always, Be extra careful with laser PSU, 9000
(actually, it’s over 40.000V)
It’s very High Tension power and it could kill you.
Be careful and remember. You

don't touch

Installing the laser Hour Meter

This is a new add-on to have a real count of the lifespan of the tube.

Wind the black wire’s counter around the laser red wire. 5 times.
And push the other end into the laser hour meter.
Install the meter were you want for an easy readings.


Next step.

  • Recalibrate optics -done, check issue 97
  • Redo a probing graph -done, check issue 97
  • I need a hand to finish cosmetic building.
    • As you can see at the beginning, I need a nice panel for all the button and manual fire solutions…
    • Due to this extra power, more electromagnetic noise is produced when firing and the electronics crash. So I put everything outside the metal box. Could be nice to re-cable everything and make a nice box around.

note: this post is linked to this issue, feel welcome to contribute.