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601 posts

Ultimate Geek
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Topic # 131108 9-Oct-2013 14:06
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Hi all, this might be something simple as quality or type of cable but I have come across this situation a number of times where a portable USB drive won't get recognized by a desktop or laptop with certain cables where as the branded cables that usually ship with the drive always seem to work.  Can someone please shed some light on this?

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3607 posts

Uber Geek
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  Reply # 911425 9-Oct-2013 15:20
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I'm guessing that the cables that fail aren't supplying enough juice to power the drive. i.e the wiring/connections  on the power circuit is flaky,

Will those dodgy cables work to connect a drive that is externally powered? If they will work, then its definitely dodgy power wiring,

If they fail to work with a powered drive then its likely that the data circuit is also bung and you should just biff the cable as it is a dud

488 posts

Ultimate Geek
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  Reply # 911427 9-Oct-2013 15:30
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This may not be of use, but a few months ago, one of the testers that works here came to me with a similar problem using the normal A-B cable that you get free with your monitor. He could not get the USB device of choice to work at 'full speed' with his PC. After some investigation, and a lot of digging through cables, it turned out to be a real problem. After a lot of further testing with cables all from Dell and HP (pre-packed with monitors) we discovered the problem to be down to the actual cable; there was a difference in detected speed of the USB capabilities from the PC to the device using very particular cables.

The symptoms were that the PC would have a message - your device is capable of higher speeds etc, like the one you get when accidentally use a USB1.1 port. The cables all came form Dell and HP and the actual cables themselves had slightly varying part numbers printed on their length. Some testing later we found that some of the cables had slightly worse quality and enough to trip whatever it was that lowered the expectation of the software. This was found to be consistent in the part number of the cable, regardless of manufacturer of the USB product or source, so my best guess is that somewhere in teh world is a cable supplier with dodgy wires.

Any cables that get this message are now destroyed on the spot (cut off the eads and tails and bin them).

Honestly I thought this problem died in the last decade, but maybe somebody found a container of old cable and started up shop again?

Anyway, to be sure, mark the cable you suspect is bung. Try it on a few different USB ports on the same PC (front and back) and if you can try it on another HDD device. Eventually, you should get a pattern - we found some brand name PCs have different driver chips on USB2 ports on PCs even though the ports seem identical - e.g. some ports are UHCI and some are EHCI (I'm still not sure what that means). We found that on branded PCs some ports on the front have a lower power output than ports on the rear and of course, some add-on ports are not connected to auxillary power as is sometimes required.

A few things to check but may be worth your sanity and of course, may save data corruption if underpowered ports etc.

Good luck.

 
 
 
 




601 posts

Ultimate Geek
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  Reply # 911457 9-Oct-2013 16:04
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Do USB cables have different wirings? I mean the one's that are supplied with self powered devices like printers and scanners comapred to ones supplied with external 2.5" HDD's. I don't have a self powered HDD to test but it could be the issue with the cable as I just tried another USB cable which is also similar to the non working one and it seems to work, just seems to be of better built quality and thick.
Will try the non working cable on a powered HDD and post results. Thanks

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Ultimate Geek
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  Reply # 911464 9-Oct-2013 16:17
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They supposed to conform, but the actual cable or plugs used may be of inferior quality.



601 posts

Ultimate Geek
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  Reply # 912088 10-Oct-2013 14:20
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Cable works ok with powered hard drive, sometimes works with portable HDD too but after some time hard drive starts making clunking noise but works perfect with a WD branded cable? Maybe it is the hard drive but then why would it work ok with a WD branded cable?

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Uber Geek
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  Reply # 912142 10-Oct-2013 15:22
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Same 4 pins are used for USB 1 & 2, some cables are just too lossy (read: "crappy") or have such poor shielding (also read: "crappy") that they won't handle the current required for a USB 2 device, especially if the ports will only output 500mA max, which anything not specifically labelled otherwise probably does. Some drives need >500mA and will either not work at all, or work poorly.

Generally speaking, the thicker the cable, the better your odds probably are of it behaving, and if it's a Y cable, using both plugs almost guarantees it to work. If the cable has a ferrite core (big round lump) on it, then it's probably, but not always, a better quality cable.

UHCI (and OHCI) is essentially USB 1, EHCI is essentially USB 2, if the right electrical characteristics exist, then a USB 2 device may well end up being driven from the UHCI controller.

XHCI replaces all 3 variants and also provides USB 3 support.




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