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el
Joined: Nov 14, 2006
Posts: 255
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 Posted: Fri Apr 24, 2009 10:16 am Post subject: HD stops working with long cables |
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Hello,
I have a 500GB external HD, which always worked up to now, using a semi-long cable (2m or so.)
Quite unexpectedly, it now stops showing up on the PC (XP SP2), I just get a message telling me 'A USB device has not been recognized'.
So I try various different things, also various cables (all about 2m), none of which worked..until I try my shortest cable (30cm at the most), which actually belongs with my portable HD.
And suddenly, the 500GB HD works perfectly normally.
I haven't got another short cable to test it with, but I'm assuming all the other cables don't work because they're too long.
The part which baffles me, is that the HD always worked with that 2m cable..and now it suddenly doesn't anymore, not with any longer cable.
What could be the reason for this?
Thanks
El |
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xavierx
Joined: Nov 06, 2004
Posts: 5425
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| Posted: Sat Apr 25, 2009 8:35 pm Post subject: |
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| Since no one else has a guess yet - gremlins?
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Bearly1227
Joined: Feb 21, 2003
Posts: 48
Location: Central MA, USA
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| Posted: Sat Apr 25, 2009 10:51 pm Post subject: Re: HD stops working with long cables [Login to view extended thread Info.] |
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| el wrote: |
Hello,
>snip
I haven't got another short cable to test it with, but I'm assuming all the other cables don't work because they're too long.
The part which baffles me, is that the HD always worked with that 2m cable..and now it suddenly doesn't anymore, not with any longer cable.
What could be the reason for this?
El |
My guess, based on a few years of cable building and very long cables for in situ testing in local harbors of delicate instruments.
My first guess is some (or one) of the signal wire got crushed, bent, broken or in some way has been reduced in size. Have you yet tried a new 2m cable?
I use a Fantom 1 TB External HDD and the cable must be about 2m. Maybe closer to 72" feet than 78". I have not had any problems with this one, although my old Maxtor HDD did die on me, due to the "case electronics failing". I removed the HDD from that case, and it worked just fine on an elongated HDD EIDE cable from inside the computercase. (yeah, yeah, I know the cpu is very tiny and not truly available to cables - just in case some weisenheimer gets too technical on us).
The key I see in your phrase is that it "used to work and now doesn't".
Have you tried the cable with anything else, other than the Ext HDD ?
Two other possibilities, though very narrow I think, is partially defective signal drivers in either the USB port or on the HDD itself.
I have never seen the driver output stage, at the chip level, of the USB ports, but I would think they must be very robust.
If you do find the case to be at fault, a number of companies sell these HDD adapter configurators that you can just plug n play the HDD on a USB port, either EIDE (PATA) or SATA.
Bob |
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drwho07
Joined: Nov 29, 2007
Posts: 1546
Location: Central FL, USA
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| Posted: Sun Apr 26, 2009 12:36 pm Post subject: [Login to view extended thread Info.] |
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Something so far not mentioned, is that the USB connectors wear, from repeated plugging in and unplugging the cables.
For troubleshooting purposes, I'd try a (powered) USB hub as the source and a new USB cable for the connection.
Something is killing the data signal from the HD.
Probably worn or funky connectors.
Years ago, there was a motherboard and HD combination, where the drive would not work if the IDE cable was longer than 9" (nine inches).
Stuff happens!
Doc  |
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el
Joined: Nov 14, 2006
Posts: 255
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| Posted: Sun Apr 26, 2009 3:53 pm Post subject: [Login to view extended thread Info.] |
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hmm 
(I highly doubt gremlins are to blame  )
well I have tried about 5 different cables, surely not all of them could've been damaged 
but no, I can't say I've tried a completely new cable..
I have, however, used various other external devices with the cables that don't work with that particular external HD..and they all work..
maybe trying a completely new cable would be an idea? I think I'll definitely give that a try..the short cable I'm currently using does also happen to be the newest of all cables..
Thanks 
El |
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grayskyes
Joined: Apr 28, 2009
Posts: 1
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| Posted: Tue Apr 28, 2009 8:52 am Post subject: [Login to view extended thread Info.] |
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Does this drive get it's power over USB or does it have an external power connection? I've seen this before when the hard drive wasn't getting enough power. Is there anyway you can try it on a different computer? If so, do you get the same results?
G |
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el
Joined: Nov 14, 2006
Posts: 255
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| Posted: Wed Apr 29, 2009 7:45 am Post subject: [Login to view extended thread Info.] |
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The HD has an external power connection..
And a portable HD that takes it's power from USB does work with those cables..which the external HD doesn't work with..
I did try the HD on another computer, a Mac, and it did appear on the computer, but the files on it didn't play normally. Like, a video file would play only video, and the audio would be missing (which isn't the case now, with the short cable).
El |
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xavierx
Joined: Nov 06, 2004
Posts: 5425
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| Posted: Wed Apr 29, 2009 8:48 pm Post subject: [Login to view extended thread Info.] |
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| Have you checked the voltage of the power supply, and the current under load? It could be dying, but not dead yet. |
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el
Joined: Nov 14, 2006
Posts: 255
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| Posted: Fri May 01, 2009 5:07 pm Post subject: [Login to view extended thread Info.] |
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I'm not really sure how to check any of that
Help?
But if I understand correctly..the HD really could be about to die on me?
El |
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Bearly1227
Joined: Feb 21, 2003
Posts: 48
Location: Central MA, USA
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| Posted: Sat May 02, 2009 8:32 am Post subject: [Login to view extended thread Info.] |
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| el wrote: |
But if I understand correctly..the HD really could be about to die on me?
El |
Maybe. SInce my last note on April 25th, My 1 TB Fantom (which uses the Western Digital - WDC WD10 EACS-00ZJB0 ) HDD, dies in a most peculiar fashion.
My first symptoms were that the files were recognized, and could be verified. But I could not "add to them" the Changes (differential backups). The symptoms changed until finally, using Win XP SP3 Disk Management tool, it said that the entire drive (almost entire, 931 Gb) was (is) "Unallocated Space".
I have to mention in passing that my most critical backups were already committed to DVD's backups, so basically the 1 TB drive was tempory backups.
On the Fantom website I saw one little note that I initially dismissed with "that's nice to know". That one tiny note said something to the effect that "It should be safe to leave the FANTOM drive powered and on the system. But that when removing it, to be sure to use the "Hardware Disconnect" in XP to make sure no problems occur!
I think, what may have happened, old fumble fingers (no names to mention) probably did not do one disconnect, and something corrupted the EMBR, you know, that Track 1 library that keeps track of everything.
I mean like even the NTFS Format was blown from the disk!! I have never seen Format blown before!! I have since reformatted to NTFS (again), but it took several hours using XP Disk Management.
By the way, if you take fancy to Fantom HDD, Buy.com has them on "reduced price on sale" for a Paltry $168.00 with a One year limited warranty.
However, Fantom.com (the Mfrs site) is asking a whopping $117.00 and change for the same USB 2.0 HDD. But, since it seems so sensitive to hot swapping the USB connection, I am not sure if I could recommend this 1 TB drive to anyone else. Unless, of course, they are highly technically skilled and understand the risk they are foisting upon theselves.
Well, I am still within the warranty period, but the packng material is elsewhere.
Good Luck,
FYI - Make DVD Backups or find alternative storage. I just don't trust the USB Ext HDD's any more, not as a long term solution!
Bob |
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xavierx
Joined: Nov 06, 2004
Posts: 5425
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| Posted: Sat May 02, 2009 7:17 pm Post subject: [Login to view extended thread Info.] |
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| el wrote: |
I'm not really sure how to check any of that
Help?
But if I understand correctly..the HD really could be about to die on me?
El |
If it works just fine with a smaller cable, my first suspicion wouldn't be the hard drive itself, but you should definitely make a backup just in case.
I was talking about the power supply dying. What you need to perform the tests is a multimeter - any Radio Shack will have one. You don't need anything fancy, but it needs to check DC voltage and current at a minimum. I'd get a digital one (they're easier).
For how to check it, first, what kind of power cable is going to the hard drive? What you need to do it put the positive multimeter lead on the positive pin/hole from the power supply cable, and then negative to negative. The problem is that some power supplies have weird pin outs (as in, more than one positive or negative). However, as long as the multimeter is set to DC voltage, you'll be fine - you won't short anything out unless you touch the same lead to two pins. You can just keep changing pins until you get the right output (there should be a label on the supply to tell you what it should be). Of course, if you never get the right voltage, there's your problem!
If you don't know how to check the power supply current, I'd recommend getting someone else to do it. Basically, you need to break the circuit and insert the multimeter in the gap to close it. That likely involves running wires between the power supply plug output plug and the hard drive enclosure (otherwise you'd need to cut the power supply wires). However, and this is REALLY important, if you mess those wires up, you could fry the hard drive! |
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el
Joined: Nov 14, 2006
Posts: 255
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| Posted: Mon May 11, 2009 12:32 pm Post subject: [Login to view extended thread Info.] |
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hmm..I suppose the best thing to do would be, make sure all the files on there are backed up, and hope it doesn't die on me..
I'm afraid I also have no idea what the EMBR is..
As for the power supply, I only know what's written on the AC-DC adapter..(at least I believe that's what it's called )
Thanks for the explanation, I think it's not the best idea if I check the voltage myself yet..I'll see if I can find someone who can do it for me :]
I really don't fancy the idea of the HD getting fried 
El |
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westom
Joined: May 11, 2009
Posts: 1
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| Posted: Mon May 11, 2009 5:57 pm Post subject: [Login to view extended thread Info.] |
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| el wrote: |
hmm..I suppose the best thing to do would be, make sure all the files on there are backed up, and hope it doesn't die on me..
... Thanks for the explanation, I think it's not the best idea if I check the voltage myself yet.. |
First, files are not read by your computer. Your computer talks to the disk drive computer via USB. That disk drive computer then reads and writes to the disk. Your problem is no communication between your computer and the disk drive computer.
Second, if you fear a meter, then do not use your cell phone in the same room as that disk drive. No. I am not joking. Your ability to harm the disk drive is equal to your cell phones ability to do same damage. Get a meter. Measure that voltage. Learn that closing a door on your fingers is a greater threat.
However, the meter can only report the worst of problems. Unfortunately some defective supplies can still appear good without a load. Without that supply also connected to the drive, a meter test can identify a defect but cannot say the power supply is good (appreciate ternary - not binary - logic applies). Still, meter is somethng you should do only because you appear to fear - which is another problem you need to eliminate to collar this problem.
Third, cables can be any length according to the USB standard - as long as a cable meets signal parameters. Some cables using better construction can be longer without problems. Others should be considered counterfeit because they do work in some conditions and yet do not meet those signal requirements. In short, swapping cables only implies a problem might exist - cannot identify a definitive answer - cable is definitively good. (see High / Full speed mode later for more information).
Now, to limit this discussion to a disk drive problem. One reason why a shorter cable works is because the signal is not distorted by that longer cable. Distorted either due to weak USB drivers (on either end), weak power supply, or cable defect. A shorter cable could mean a weak USB driver or power supply problem is reduced enough so that your computer can talk to the disk drive computer.
To make a clean answer even more vague - some device will only use that cable in Full speed mode. Your drive may use it in High speed mode. Therefore a defective cable in High speed mode can work just fine in Full speed mode. Unfortunately, I don't know of any layman tool to get a better answer such as which mode a USB device is actually operating in. But, what do the written specs say?
USB ports are actually two different devices in one connector. For example, your computer's High speed mode semiconductors could be damaged. But the Full speed mode semiconductors work just fine. If making conclusions only using observation, you would declare that USB port good when, in reality, it was defective. This paragraph demonstrated why one must always understand the underlying principles before making conclusions from tests. Why testing without learning underlying facts easily creates false conclusions - also called junk science.
Having said all that, and doing testing, what in your tests better identified a suspect? That also means posting 'why'. Of course, answers are always more useful if your every post had numbers - constantly - such as the spec numbers from that power supply. And numbers from the meter reading. Numbers often tell me things you did not even suspect. Your help will only be as useful as the facts, numbers, and specs that your provide.
If you think you understood this post in the first read, then you are only fooling yourself. Another reason why we repair things. We learn the better answers often require multiple rereads.
Unfortunately, USB troubleshooting is not easy due to few useful diagnostic tools combined with so many who know without first learning how USB really works. Measure that power supply with a meter. Try to discover other devices that only operate in High speed mode and test your cables on them. Try your drive on some other USB port device on the theory that your computer's High speed port is defective while its Full speed port is OK. Appreciate why longer cables may overly distort signals between USB port and device - and that some may be counterfeit.. Understand that you have defined a problem between your computer and the disk drive computer - not a problem between disk drive computer and files on the hard disk.
Oh. And happy hunting. Fun is in solving problems like this - including learning the 'reason why'. |
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el
Joined: Nov 14, 2006
Posts: 255
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| Posted: Wed Oct 07, 2009 4:02 pm Post subject: [Login to view extended thread Info.] |
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And here it happened too..I wasn't notified of further replies
The hard drive quite randomly decided to work again..we've now replaced it for a larger one anyway..
Thank you for the reply..which I wasn't notified of
El |
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