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Looking to repair a fiber optic cable on a MPS-8033

Discussion in 'Electronic Repair' started by Jay, Aug 28, 2007.

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  1. Jay

    Jay Guest

    Hello all,

    I have a piece of test equipment that needs repair, and which goes beyond
    my skills in the field of electronics. It's a 1550nm ILX Lightwave
    MPS-8033/03, which has had a botched repair attempt - The fiber optic
    cable between the laser and the front panel was severely kinked (pretty
    much 180 degrees!), and no longer appears to conduct light.

    The instrument can be seen here:
    http://www.ilxlightwave.com/propgs/fiber_optic_instruments_8033.html

    The laser is from Lucent technologies, and looking at a PDF of the device
    it would appear that the 32" of fiber optic cable comes with the laser -
    in other words, not detachable. So, basically, I'm looking for a
    professional in the US (I am located in MA) who can cut about 3" of the
    cable out, then splice it, as I have neither the tools nor the knowledge
    to do so myself. I would also be interested in any tips on reasonably
    priced repair facilities that do this kind of work. (The manufacturer
    wants a ridiculous amount for the repair.)

    If interested, please email 66gtojayw AT comcast.net, or reply here in the
    groups. Thanks!
     
  2. With the proper equipment (fusion splicer, some experience) this shouldn't
    be difficult.

    However, when you say "kinked 180 degrees", are you sure it's really broken
    internally? That's the only way it would fail. How tight is the kink? And
    how did it get kinked? A dead laser would produce the same symptoms, right?

    Will also post to sci.optics .

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  3. Jay

    Jay Guest

    Neither of which I have... :) ($18K USD. Ouch!)
    Well, this instrument was originally missing it's key. An overzealous
    "tech" [cough, cough] figured he/she could replace the keyswitch, and
    dis-assembled and removed the front panel of the equipment. In order to do
    this, they pulled the nicely looped fiber optic cable hard against two of
    the ties holding the loop against the solder side of the lower circuit
    board. Now it's come to MY bench for repair... I don't know how I can be
    sure that it's broken internally, but it is severely deformed and
    stretched looking. If one were to take a piece of really thin fiber and
    pull it tight around the radius of a pin's diameter, that would pretty
    much describe the cable - kinks are in two places about two inches apart.
    Using an optical power meter tuned to 1550nm I was unable to get any
    reading, no matter how I tried to straighten the kinks.
    Yeah, that's always a possibility. I'd use a scope to check the laser
    drive, but I've no idea what it would look like as this is my first
    experience with this type of stuff. The laser does get comfortably warm to
    the touch after a few minutes and seems to vary thermally depending on the
    output power I dial in, so I'm ASSuming and hoping that it's still
    functioning. ;) Given those conditions, would the laser appear to be
    working?

    I don't think that Lucent is making these devices anymore, but the laser
    looks similar to the device on this website:
    http://www.intenseco.com/products/inslam/?View=S
    Thanks Sam.
     
  4. Well, maybe $2-3K on eBay. :) At the bottom of the dot.bomb, they were
    going for under $1K. The experience might cost more though. :)
    Doesn't sound good. Especially the stretched part. Fibers will bend around
    a small radius without breaking, but not a pin diameter.
    Likely working but no guarantee.
    Someone should be able to point you to a place that has a fusion splicer.

    But to do a one-off repair at a reasonable price, may take a friend of a
    friend....

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  5. At risk of going beyond my ground.....

    That laser seems to be accepting a drive correctly, but the output might do
    one of two things, either it will have died by retroreflection from a large
    return of light from the damaged point in the fibre, or it will be active,
    because energy can get out (as heat) without returning to kill the diode.

    If this laser is powerful enough, you might be able to detect heat at the
    damaged point in the fibre. Try taping it to a small Peltier (that has lots
    of couples in it) and seeing if you see a few millivolts on the Peltier
    wires when you switch on the laser. Even a 5 mW laser ought to read
    something consistent if you control for ambient heat and watch a few
    switching transitions.

    The one thing the Peltier test can't tell you is if the laser is low power,
    and the fibre is reflecting energy back to the diode, it can't tell you if
    the diode is dead or not, but for power greater than around 50 mW it should
    be a reliable test.
     
  6. If you look at the fiber with an infrared viewer and it is the fiber that is
    is broken and not the laser, you should see a lot of scattered light that
    emanates from the fiber core at the breaking point.

    Cheers,
    Jürgen
     
  7. Might want to try finding the laser diode inside on ebay. I've seen a
    lot of DFB diodes in that range on there. Other than that you're only
    option is to get the fiber spliced. It's really not that difficult if
    you cleanly cleave it and use a fusion splicer. The part that sucks is
    that one of the pezio positioners on my splicer is fried.
     
  8. Jay

    Jay Guest

    Hopefully, the latter is the case. I had no idea that the light could
    reflect back into the diode and destroy it... As a side note, the folks at
    ILX refused to do the splice work, and would only replace the entire laser
    assembly at a cost of minimum cost of $1500. Nice support!

    At this point, I'm a bit hesitant to power up the instrument again. I
    received a response by email, and may have a contact who can do the work
    for me, he's stated that if the cable is single mode fiber, it shouldn't
    be a difficult operation. I'll follow up when it's done and report the
    outcome for any who are interested. Thanks to everyone who took the time
    to respond!
     
  9. wy

    wy Guest

    I had a broken-fiber problem before on another type of laser (SM
    fiber). And we had it spliced. Using a fiber fault finder, the
    engineer located the fault within 2mm. Not bad at all. The resulting
    fiber is 1" shorter with a little power drop (never calibrated it
    carefully) from the laser. It costed us only $50.
     
  10. Jay

    Jay Guest

    Out of curiosity (and future reference), where did you have the work done?
     
  11. Hi Sam,

    what has happend with alt.lasers?!!

    A. Roithner
     
  12. Nothing. :)

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  13. Sjouke Burry

    Sjouke Burry Guest

    It failed to lase, you have to adjust the cavity.
     
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