Connect with us

cat5 cable tester

Discussion in 'Electronic Components' started by b.a. marcus, Dec 30, 2003.

Scroll to continue with content
  1. b.a. marcus

    b.a. marcus Guest

  2. I'm not trying to disparage the project, but this really doesn't test
    cat5 cable. It tests for continuity, but not shorts, so you could
    call it a half test(?) But its biggest drawback is that it cannot
    detect split pairs. IMHO, if you use a piece of test equipment that
    tells you that the device under test is okay, but you replace the DUT
    and it cures the problem, then using that test equipment is worse than
    not having it at all, because it misleads you and wastes your time.

    At work, I do this testing daily. I used to get complaints that the
    cabling in the walls, which is my responsibility, isn't working
    properly. The tech from another site will tell me that the PC will
    work on the network at 10Mb, but not at 100. So I drags out the Fluke
    DSP-2000 (costs $5000) and test the cabling. And the cabling in the
    wall passes the test okay.

    But I test the patch cord between the wall and the PC and it tests
    BAD. I tell this to the tech, and he says, "But I checked it with my
    Byte Brothers tester, and it tests okay!" Yeah, I tell him, because
    your POS tester doesn't detect split pairs, and when you assembled the
    patch cord with your crimping tool, you got the wires transposed so
    they are a split pair.

    See, he has been using that patchcord for years on an old PC that's
    only running at 10 Mb, so it works, but probably has a lotta bad
    packets and errors. Now that he is using it on a PC with a 100Nb NIC,
    it really has major problems with bad packets and errors. Back when
    the dufus made the patch cord, he didn't realize that he was making
    the cable wrong.

    And adding insult to injury is that his POS tester won't tell him what
    the problem is, so he's blaming the wall wiring or anything else
    instead.

    Anyway, after embarrassing a few techs by proving with my FLuke that
    their cabling is bogus, I've finally got them to test the setup with a
    different patch cable -- usually a store bought, aka not a homemade,
    patch cord -- before they tell us the wall wiring is bad. And I've
    asked the head honcho to stop the techs from wasting their time making
    their patch cords, and use store bought ones, which are pretested.
    Well, supposedly, but then that's a whole 'nother story. And I have
    another coupla horror stories that occurred recently, but you will
    probably have to see them on comp.dcom.cabling newsgroup, where this
    post really belongs.

    BTW, you can get a Siemon STM-8 tester which detects split pairs for a
    couple hundred dollars. Or if you wanna waste time, build the
    project, but it will probably cost more than the $50 that a cheap
    tester costs.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  3. b.a. marcus

    b.a. marcus Guest

    I found a cheap tester at Fry's for around $30 dollars. The project
    costs more in my time then it does parts. The project does test for
    transposed wires and, yes, it is a continuity/polarity tester. Besides
    the fact that a tech that transposes wires has to be an idiot. The
    "shifted" or "transposed" pairs can be detected by the missing pulse.
    The Decade counter resets on the 6th count instead of the 5th. The way
    I see it, it's major drawback is that it doesn't test cable length or
    short cicuits (which may be tested by other means). But I can darn
    near guarantee that if this tester says the cable is "OK", then the
    cable IS "OK". If you need an authoritative "Yes" answer, this is
    pretty darn close. If I charged myself $50 dollars and hour to build
    the tester, it wouldn't be worth my time. But I estimate the cost of
    parts to be under $10. And all but one of the parts can be found in an
    old POS radio.

    A hammer needs a nail but it also needs a thumb and 4 fingers.
    Thanx for your input.

    Bruce
     
  4. b.a. marcus

    b.a. marcus Guest

  5. Unfortunatelyu there are contractors that hire idiots to install cat5.
    Fortunately they get weeded out pretty quuickly, buit before they do,
    they can make some serious errors. But yeah, you seldom run into this
    problem.
    In most cases of a cat5 cabling problem where the cabling was
    previously working, the Fluke tells me it's an open wire. Usually
    this is at either the wall jack or patch panel, and simply repunching
    down both ends takes care of the problem. For years I got by without
    the Fluke (or any tester, for that matter), just by doing this simple
    procedure. If that didn't fix the problem, then I'd replace the
    cable.

    So I never needed a tester. And the nice thing about this is that it
    costs nothing. And it never gives you a false answer.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  6. It makes more sense now. Needs a battery and on/off switch. Nothing
    says what the battery V is, but I'd assume 9V.

    The link to the All About site shows a SCS, nothing to do with the PUT
    or an oscillator.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
  7. b.a. marcus

    b.a. marcus Guest

    ....

    9Volts. Or 12 if you want to carry a transformer around too... :)
    That'll make for some bright LED's.

    Once I saw the mistake I threw it together real quick and forgot about
    the voltage.

    SCS... hmmm, musta been in a rush on that one too.
     
  8. b.a. marcus

    b.a. marcus Guest

    I think x555 is the best way to go for the oscillator After all. The
    PUT is sensitive to changes in voltage and quits oscillating when the
    battery gets low. The only way to solve the problem is to add a
    voltage regulator which complicates the circuit as much as a x555
    does.

    I have to say that I have not found a better cable tester on the web
    than mine. I guess thats a matter of opinion though and like Watson
    said, "Everybody has one."

    Nevertheless, I have not had an opportunity to sit down and hash out
    the figures on the PUT (see my PUT post). Actually I found a circuit
    that has a "better", I mean more simple, oscillator. And I can't
    believe I never thought of it.
    http://www.atomiccomputers.com/projects/sutton-001.html
    I have actually driven the decade counter in this manner when I was
    testing the decade counter with a 555 and an LED to indicate pulses.

    Well, it's a learning experience. Started working on this thing back
    in August 03. That's when I built the first tester. Never built an
    electronics project before that.

    Watson, I think this post fits better here than it does in cabling
    now. You were right about the 555 but not about this post. :) just
    kidding.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-