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USB cord differences

Discussion in 'Hardware' started by Zygmo, Dec 16, 2011.

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  1. Zygmo

    Zygmo Thread Starter

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    Hey, Guys...I have a question about some USB cords.

    I have noticed that some USB cords will not work will some HDDs, or at least not as well. Usually, if one won't work, I have to switch to a larger cord. Usually, the larger the HDD capacity, the more likely that the small diameter cords won't work.

    I have one cord (came with a 120GB WD portable HDD) that is a double cord. It has the standard USB plug on the end that goes to the computer, and one large cord with the usual small plug for portable HDDs, and one smaller cord with a standard USB plug (stamped POWER).

    I recently purchased a 7" Polaroid portable media player. It came with a large diameter cord, with the standard USB plug on one end, and the same plug that the WD HDD uses on the other. When plugged into the computer, it works for data transfer and as a battery recharger. When first plugged in, a large graphic of a battery comes up on the player's screen, with a representation of power being added to the battery. (A slow movement of a bar going up and down the battery.)

    However, when using the large double cord mentioned above, the graphic of the battery filling up moves much faster, and the player appears to charge much quicker. Of course, I am only using the larger cord of the double which looks just like the cord that came with the player...the other smaller cord of the double is not hooked to anything. (as a matter of fact, I have not found any use for the smaller cord of the double yet)

    By the way, the computer is affected when using this cord with the player too....the cursor blinks
    rapidly, and some programs seem to lock up.

    Any ideas about what is going on? I can furnish a picture of the cord if my description is not clear.

    Thanks.
     
  2. Elvandil

    Elvandil

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    Some of the better cable (larger usually) have shielding in the covering to prevent outside interference from interfering with the data transmission. Devices that have high rates of transmission would obviously benefit from that since data packets that are not sound need to be retransmitted, slowing the transfer.
     
  3. Zygmo

    Zygmo Thread Starter

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    That makes sense, Elvandil. However, I have some small diameter clear cables that show the weaved shielding, and they don't always work with the larger HDDs. Of course...there may be shielding, and then there may be SHIELDING...I don't know if some are better than others.

    But, this still does not account for the double cord appearing to interfere with the computer. If it has good shielding, it should be less likely to interfere. By the way...I told you wrong in my first post...this double cord came with a 250GB Maxtor USB drive. And I just realized that when using this same cord with the 120 WD drive that I mentioned in my first post, some glitches have shown up. When used with the Maxtor it came with...everything works fine. So I don't see how it could be a faulty cord.

    I wish now that I had kept the paperwork that came with the Maxtor, to see why it came with the double cord. (I mean...who reads instructions...right??) :rolleyes:
     
  4. Triple6

    Triple6 Moderator

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    The double end or Y cable is to allow the drive/device to draw power from each of the two ports as each port can only supply up to a max of 500 milli-amps of power, and some don't seem to deliver even that much.
     
  5. Zygmo

    Zygmo Thread Starter

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    Ok, Triple6...that had occurred to me...but I had no way to verify it, and was afraid to try it. Plus the fact that the other standard USB plug is on a long wire (same length as the one that plugs into the HDD, or video player). I would assume that if you are supposed to use both USB plugs to send power to a unit, they would both be on the same end of the double cord.

    Anyway, accepting that you are correct, do you think it would be possible for this to send too much power for recharging the batteries in my video player? The manual (I use the term loosely!) does not say anything about that. And, it is a joke to notify Polaroid with a question...they don't respond.

    Thanks for your help.
     
  6. Triple6

    Triple6 Moderator

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  7. Elvandil

    Elvandil

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    Just a note: With those y-cables, one is a normal USB cable with the data connections, but the other is power-only so that the machine does not see 2 separate devices being connected by USB. The machine should not detect anything when the power-only connector is plugged in.

    And, yes, insulation and shielding differ. I've had some of those cheap, roll-up USB cables that work fine for mice or power, but caused problems with a hard drive. Generally, the smaller the diameter, the less they are shielded for the correct frequency range.
     
  8. Zygmo

    Zygmo Thread Starter

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    Ok, Triple. Thank you, about the fact that devices only draw the power they need. You and Elvandil are right...I understand how this works now. One of the cords is just power...no data is carried.

    About the misunderstanding about the cord...in the pic you refer to, the extra (power only) cord is short, since it would normally be plugged in to the computer very near where the other data/power cord goes. On my cord, the power only USB cord is as long as the data/power cord that goes out to the device (both are about 32 inches long). That is what was throwing me off on understanding the exact use of this cord. Of course, this does allow you to plug the extra power USB plug into a USB at the front of the computer, if you run out of them in the back.

    There are some other strange things about this double cord, and one of my other cords. But...it made my head spin just trying to explain it all here...so I gave up. It is not important anyway...as long as I keep the correct cord with the HDD that acts strange with any other cord, everything works!

    Thanks.
     
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