Troubleshooting - Laser Does Not Light

After getting my laser installed and connected I was unable to get it functional.  I installed the hardware using JTech's and Phil's (source of the mounting bracket) instructions and all that went fine.  I then moved on to JTech's instructions for focusing the laser.

Following those instructions, I was unable to get the laser to light.  I emailed JTech and got a prompt and helpful response.  After then emailing back and forth with them asking me to check this or check that and my findings of those tasks they determined that the laser module was bad.  I was still under warranty so they sent me a replacement which arrived 2 days later.  I connected it and everything worked.  I sent the bad one back to them using the pre-paid mailing slip they had provided me.  A big Thank You goes to Jay at JTech.

First it would be good to see the driver board's components as some of the troubleshooting points reference these items:

Following are some notes regarding the things Jay told me and had me check.

• First was to make sure the board was on and ready.  This basically means "Is it powered up?"  In my case it was as the fans were running and the Laser Enabled LED was lit.  Here is the power up sequence:

1. SAFETY POINT - Make sure the Mode Selector Switch is in the Input Control Mode position.  Otherwise, if it is in the CW Mode then the laser light may come on at the end of these steps.  It would also be a good idea to have your safety goggles on just in case.
2. Power up the X-Controller.
3. Press the Reset Switch.  This matters only if you have removed power from the board.  If power has been removed then you should hear a click of the interlock relay when you press the Reset Switch. (The Reset Switch only matters if the board has lost power.  This is provided for the case when, for example, your house looses power when the laser was on.  If you were to leave and the power comes back on then your laser will not turn on automatically and burn the house down.)
4. Turn the Key Switch on.  I have read that you have to slightly push in on it before it will turn which is what I have to do with mine.
5. Flip the Power Switch to the on position (the '|' symbol).  At this point the fans should come on and the Laser Enable LED should light up.

• The Mode Selector Switch - When set to the left it will be in CW Mode and the laser will run at light and run full power.  When slid to the right the laser's output power can vary and is controlled via GCode.  I will be using the GCode controller option so I had it to the right.  I was asked to move it to the left, CW mode, and told the laser light would come one and the Laser On LED should light. (This can be done with the laser module not connected to the board but, if you do have it connected be sure to wear the safety goggles to prevent eye injury.)  This is a test for the board itself - if the Laser On LED did not light then the board is bad.  If it did come on then I should switch back to the Input Control Mode and, using Universal GCode Sender, send the command "G1 F4000 M03 S11".  I was told that the laser should light and, additionally, "In laser mode, the laser will only turn on in G1 states and that some lasers will have a threshold of over S5 to turn it on.  Try S11 and then work back down."  In my case it did not light and the laser module was determined to be at fault.
• To determine if a signal was being sent properly from the X-Controller I had to use a volt meter.  Measuring the voltage at the H2 Control Signal Input, using Universal GCode Sender, I sent the command "G1 F4000 M03 S255".  In GRBL 1.1 I should then read 5V at H2.  In my case I read 4.8V which was close enough to confirm that the connection to the laser board was working.  Because I am a curious person I tried other S values, like 100 and 200, and read lower voltage values at H2.
• One of the things I noticed is that the Laser On LED would light with varying brightness which mirrored the laser's intensity.  In other words, if the laser was dimly lit then the LED would also be dimly lit.  Placing the Mode Selector Switch in CW Mode would cause the laser to come on brightly (be sure to have nonburnable material under the beam) and the LED would also be brightly lit.