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  1. #1
    Registered
    Join Date
    Sep 2014
    Posts
    128

    It ain't always a dead tube.

    Should first say, background in mechanical engineering, so well aware that 99% of laymen over-tighten fasteners rather than under-tighten them... so I tend to be delicate.

    The problem. Went out to the machine yesterday to do a job, job was set from customer's dxf design files, and I just selected the settings for each layer / process from the library for that material, eg "cut 10 mm acrylic with 4" lens"

    It was ****, didn't cut through, hello, clean optics.

    Didn't cut through.

    Start playing around with the manual (pot) beam power control, start playing around by altering the library power setting for that material.

    Library said it should cut clean and perfect at selected speed at 31 watts, eventually got the desired cut at 41 watts. look at tube while it is running, some flickering.... talk to supplier, ooer missus, sounds like a dying tube.

    Didn't buy this, didn't feel right in my gut, you don't get a sudden 30% power drop essentially overnight, started thinking it through.

    At library settings was going between 6 and 8 mm through the 10 mm acrylic.

    Today, machine switched off at wall for safety.

    Open tube cover, gently push eye connector on earth end, seems solid, gently push eye connector on positive end, and the just pinch tight screw undoes and it goes loose....

    Grab screwdriver, gently pinch up +ve terminal on tube, fire up machine with default library settings and run test job with library settings, *just* cuts through, guessing I'm down maybe a couple % on expected power for library settings.

    Inspect mirrors and lenses, oh ****, guess what ******* spray silicone lubed the runners without covering the mirrors, #2 mirror slightly dirty and 4" lens slightly dirty.

    Moral of the story, HT auto ignition electrics share electrical characteristics with EHT laser tube electrics, connection has to be perfect, otherwise it will *look* just like a dead tube.

    Job for tomorrow is strip, emery and refit ALL EHT and laser psu connections, torque properly, may even do a spot of hot glue.

    Job for tonight, drink beer with money saved not buying a new tube that simply was not needed... ring any bells with garages swapping out expensive "dead" parts that weren't before finding the problem was a 5 buck connector?

    I reckon the vendor's diagnostic thought process was solid state electronic modules are working, ergo it's the tube, and then I'd have been sitting there saying RECI tubes just aren't that good (mine is 12 months from manufacture, 7 months from machine purchase) which would have been bull****. HTH etc

  2. #2
    Registered
    Join Date
    Mar 2015
    Posts
    79

    Re: It ain't always a dead tube.

    Great write up. My machine is do in a couple weeks. I think I will take your advice and do a good pre-run inspection.
    Thank you

    Gozzie

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