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Ribbon Cable Resistance, how much is too much? — Parallax Forums

Ribbon Cable Resistance, how much is too much?

idleupidleup Posts: 46
edited 2005-10-22 00:15 in General Discussion
How much resistance is as good as O.FL (infinite)? I created a ribbon cable to connect to headers and wanted to make sure that none of the wires were shorting together.·I am getting between 900k - 1M ohms·across·wires. Is that considered shorting them?

- Matt·

Comments

  • ForrestForrest Posts: 1,341
    edited 2005-10-21 10:40
    I think you should get higher isolation values. Check for flux residue around your ribbon cable headers/sockets and clean with a toothbrush and water abd/or IPA.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2005-10-21 15:56
    I cannot seem to get a clear idea of how you are measuring.

    Is the cable connected to a board, or are you just measure from pin-to-pin? And is the board 'hand soldered'?
    After all, it really makes a difference in the kind of advice you require.

    Regarding solder flux, I always try to clean up immediately as it becomes more difficult later. I use rosin cord solder, so I clean up with a toothbrush and rubbing alcohol. Water might not work well.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

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  • idleupidleup Posts: 46
    edited 2005-10-21 16:07
    It is not connected to a board, this test is just on the cable. I am just jamming some wire into the connector plugs at the ends of the ribbon cable and using the ohm meter to check if·the resistance. The cable was pretty easy to create, You just clamp the·plugs on the cable and the little teeth bite into the ribbon. There isnt really a lot you can do wrong...

    So·I guess·my question should really be "at what resistance is it considered shorting the wires?"

    - Matt
  • stamptrolstamptrol Posts: 1,731
    edited 2005-10-21 16:38
    Matt,

    As you've noted, the connectors are made to do a specific job of creating a secure connection. In my experience, if the process gets screwed up, the conductors will definitly be shorted, like 50 ohms or less.

    In the circumstance you describe (9ooK - 1meg), no-one would consider that anything but an open circuit. By the way, were you holding the meter probes onto the conductors with your fingers? If so, you might really have been measuring the wires in parallel with your body!

    Cheers,

    Tom
  • idleupidleup Posts: 46
    edited 2005-10-21 17:36
    Interestingly, I was holding the probes on the wires with my fingers. I will try doing it again not touching them.

    - Matt
  • steve_bsteve_b Posts: 1,563
    edited 2005-10-22 00:15
    We canadians eat a lot of salted meat (preserves from the traplines for winter! [noparse];)[/noparse] )....anyhow, I have a high salinity in my skin and have to be careful when I'm measuring resistance AND holding the devices too....Thrown me off more than once!

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
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