Epilog Legend 36EXT Intermittent Laser Firing Advice?

[Andrew D'Alessio]

Hey all,

I'm looking for a bit of advice in diagnosing and rectifying an intermittent laser firing issue with an Epilog Legend EXT36 75W.
It was purchased 2nd hand with the knowledge that the tube had last been refurbished in 2016 and as far as I'm aware was still in use without fault.

I'm finding that that when vector cutting or rasterising that the laser source will intermittently fire when told to fire. For example, if I were to vector cut a few shapes the laser would cut one flawlessly, move to the next cut and then not fire for the entire cut, move the the next cut and then fire again flawlessly, this would continue cutting less and less frequently until it doesn't cut anymore.
As it's old, it was somewhat expected and sounded like a laser issue, I removed the laser unit and sent it off for testing and refurbishment where it was found to be down on power, re-gassed and test fired with them without issue.
However the fault has persisted upon re-fitting.

Here's what I've checked and tested without any behaviour change.

• - Interlocks have been bypassed on the rear of the control panel.
• - Both PSUs hold 48v stable during use/firing.
• - All PCB connectors re-seated and power loom continuity checked.
• - Environment temperature was around 10-15c but has now been moved to a heated 20-25c office without any change.
• - Diagnostic LEDs on motherboard appear to check out okay as per the service manual.
• - The Coherant laser source LEDs all appear to function okay with Green + Red lit and Yellow lighting when firing is attempted (although it appears dim?).
• - Various drivers/versions of Coral/Inkscape and PCs for processing.
• - Leaving the machine or power cycling the machine sometimes appears to help it fire again for a short period, but I'm unable to reliably reproduce this.

When using the align laser mode to manually fire the laser, it can be coaxed back into firing by tripping the interlock over and over until it will fire again, sometimes until the button is pressed again or sometimes for minutes until the above behaviour happens again.


I have experience with CO2 lasers but this is my first RF laser and I'm at a bit of a loss now after sinking a fair amount of money into it.
I've searched around but can't find anything like this fault on here or online so any advice/things to check would be appreciated!

[Kev Williams]

For over 40 years now I've ran computer controlled engraving, sign making and other various equipment. I have had MANY similar issues to yours over the years. And I would guess at least 95% of all similar issues are caused by one issue: Poor Electrical Connection...
Ironically, just 2 days ago I found that my 40 year old New Hermes Concept 2000 tool engraver (with a Q1E driver upgrade that's over 20 years old), wouldn't finish an engraving task- it would start, get thru 1 to several parts of what it was engraving, then simply stop 'following orders' and the cutter head would continue in a straight line, up, down, left or right, depending on it's last move, and just continue to infinity- which of course is the machine's physical limits... I've had several machines do this over the years-- As to lasers, I bought a used GCC Explorer laser from a board member back in 2015 I think it was, and about once a year it starts going bonkers, like stop firing the laser but still moving, or just the opposite, or it'll simply just plain quit altogether...

The fix is simple... get a couple of cans of CRC Electronics Cleaner spray, then proceed to find every connector plug that can be disconnected that you can find, EVERYwhere, motherboards, control boards EVERY ONE you can find- then douse both ends liberally with the spray, then plug them back in. It's never failed me on the Explorer, or any other machine. It's exactly what I did 4 hours ago on the C2000, and after 20 or more test passes it's doing its job flawlessly. Couple of days ago best it would was run the word LIFT maybe twice before it would run off. Most times it wouldn't even finish the "L"...

Not all of my machines have required a connector spraydown, but most have, and it's surprising that, unless something is truly bad, it always helps...

Give it a try, stuff's sold at most auto parts stores and Walmart-- The "basic" stuff is the QD Electronics cleaner, and the neat stuff is the 'lectro-Motive' cleaner, which is okay to spray on 'live' electric connection-- I actually spray it right into my engraving machine motors while they're running to clean out old carbon-brush dust. Totally non-flammable. It's main ingredient is actually dry-cleaning solution! Cheap fix if it works!

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