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Thread: Need help with laser tube repair

  1. #1

    Need help with laser tube repair

    I have a Coherent GEM 50 watt laser tube that I believe has a RF problem. Tube will put out 80 watts intermittently.
    Coherent does not support repair of this tube any longer and neither does Epilog.
    I have talked to Photovac and they want a $525 evaluation fee and they estimate $6100 to repair RF system and recharge the tube.
    Evergreen laser is estimating $3650 total; $2150 for recharge and $1500 for RF repair but the RF repair cost is a guess until they look at it.
    Laser Innovations is estimating 4 weeks before they can even evaluate it and won't give an estimate until they look at it.
    Does anyone have any experience with these companies or have another source for diagnosing and repairing this tube?

  2. #2
    Join Date
    Apr 2010
    Houston. Tx
    Welcome to SMC Dave. You are facing the nightmare all of us have here with older laser systems. I had my Gem 60 go down about 8 months ago and went through the same thing as you. After a lot of research, I decided to send mine back to Epilog for evaluation, yes it was more expensive 3500.00 to be exact. I wasn't sure if it was the tube or RF that was the problem, but with epilog, they are getting their tubes directly from Coherent so I knew the charge would be good if that were the problem. Also, Epilog would check the tube and if it was good they refund the tube price and send the RF instead. That is, I was in hurry and had them send me a tube, before they had received mine for evaluation. Turned out the tube was bad and everything went smoothly. Now, as for the other companies, I was told that it might be several days after receiving my tube before they knew if the tube was bad. I didn't have that kinda time.

    I believe the price from Epilog has dropped several hundred dollars now, but you would need to confirm.

    Epilog Fusion Fiber 30 watt
    Epilog 36 EXT 75 watt
    Epilog 36 EXT 60watt x 2
    Epilog 32Ex 60watt (new tube, putting out 72 watts)
    Epilog Summit 25watt x2
    IL-60 2 x 100 watts 60" x 120"
    Corel X6
    Adobe CS6 Master Edition

  3. #3
    Last I talked with Epilog about a Synrad tube for my Radius.
    I was told that they send them out for repair and are only
    warrentied for I believe it was 60 days. I checked with PhotVac
    and they quoted less than half of what Epilog did and said warrenty
    was 2 years. Dave sorry to hear that it is going to cost that much.
    My 25 watt was quoted at $1400. Could be the manufactere of the
    tube that made the difference.
    Martin Boekers

    1 - Epilog Radius 25watt laser 1998
    1 - Epilog Legend EXT36 75watt laser 2005
    1 - Epilog Legend EXT36 75watt laser 2007
    1 - Epilog Fusion M2 32 120watt laser with camera 2015
    2 - Geo Knight K20S 16x20 Heat Press
    Geo Knight K Mug Press,
    Ricoh GX-7000 Dye Sub Printer
    Zerox Phaser 6360 Laser Printer
    numerous other tools and implements
    of distruction/distraction!

  4. #4
    Does your Tube dropping its power , like its taking double the time to cut as its done previously.....?

    How did you confirm its the RF problem?

    If suddenly the Deos tube is not emitting its laser, then its RF electronics part to be seen.
    Epilog Legend 24 EX - 75W with Rotary
    Fiber laser Marker 20w ( IPG)
    Flat bed heat press, Mug printing, Epson 230 x 2
    Flame Polishing machine, Acrylic Bender, Nicejet Flatbed printer A3+, Electrochemical etcher.
    "If you think you can or you cannot - you're right" HENRY FORD

  5. #5
    Join Date
    Jul 2010
    Portland Oregon
    I used PhotoVac to do our laser tube repair. They indicated that they would get the tube from Synrad anyway because they do their work for the older tubes. I suspect it is also the case for the other companies. The work was performed very well, our 25W tube is now putting out 31W as they measure that and provide a test block of acrylic to prove that the laser works. The only thing that sort of bugged me was their payment policies as it seems a bit over the top but perhaps they have been stiffed to many times. There really aren't many options so I say go with PhotoVac.

    WWI and Golden Age R/C scale model airplane kits
    25W ULS 25ER, AutoCAD 2000i

  6. #6
    Thanks for the recommendation.

  7. #7
    Thanks for the info.
    We will talk to Epilog again as on the first call they said they could not repair the GEM 50 any longer.

  8. #8
    Yes it will have 80 watts one day and works fine. The next day nothing. A day later works fine with 80 watts again.
    That is why we think it is the RF as the tube seems fine when it works.

  9. #9
    You could well be right that it is an intermittent in the RF board - but is there any chance the intermittent is somewhere else?

    I assume that the rest of the machine (i.e. control panel) stays alive when you have the problem - you just lose the laser output. If that is the case - could there be an intermittent in the laser power supply? Maybe you could connect a meter or load (eg an indicator lamp) and try to run the laser. If you lose the lamp when you lose the laser output then then it's on the power supply side. Sometimes a power supply will have a thermal problem.

    Or is there any chance that the connection between the mainboard and laser is intermittent?

    Don't want to get your hopes up that it is something less than the laser tube but maybe it would be worth it to explore some possibilities. Can you get any troubleshooting info from Epilog to isolate the problem? If you can get hold of a tech at Epilog maybe they will at least give you the procedure they would have used even if it is no longer officially supported.

  10. #10
    Join Date
    Dec 2004
    Southern California
    Check the voltage of the power supplies they should be a solid +48V. You may have a power supply issue instead of the tube.
    Mike Mackenzie
    Sales and Service of Universal Laser Systems

  11. #11
    Hi Mike,
    Yes the power supply seems good.

  12. #12
    Hi Richard,
    Yes it looks like the power supply is good.
    Thanks for the help.

  13. #13
    When you say the supply is "good", do you mean that the proper output voltage is present when probed? Or exactly how did you determine that it is good?

    You said " . . . it will have 80 watts one day and works fine. The next day nothing. A day later works fine with 80 watts again."

    Does it always fail from a cold start? Or have you ever lost laser output while operating?

    If it has demonstrated a failure of the output during a lasering session, then I still think it would be best to try to use the machine with a light bulb and voltmeter in parallel with the laser tube load. If the power supply drops out for any reason while you are working, you will see the lamp flash off - check the meter at this instant as well and see what the supply reads during an interval after failure.

    If the tube won't fire from a cold start in the morning, and the pre-wired voltmeter is showing 48V present, then I guess I'd have to agree that the power supply probably isn't the culprit. (You want the meter prewired to the output so you don't disturb anything.)

    If it won't start up some days from a cold start, then it isn't a thermal intermittent, but there could be other causes of an intermittent. I'd sure look hard for that intermittent in case it was something easy to fix. If you absolutely-positively can rule out the supply, then I'd even be inclined to look at the RF board, connectors (mainboard side as well), etc to see if there is anything that could be causing an intermittent. (Loose pin in connector, pinched wiring harness, bad solder joint, smoked or overheated components, brown spots on PCB, etc)

    Is the RF board easy to get to? Maybe you could hire a tech to help troubleshoot it. A schematic from Epilog or Coherent would help - (since they have said they are not interested in repairing it I would think they would be generous in providing the schematic and troubleshooting info.)

    Is there a tickle setting on this tube/mainboard? Perhaps you could try changing the tickle threshold and see if that does anything. The tickle should be set so that the laser is on the verge of lasing but does not lase on its own.

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