Partial Loss of USB (Strange)

[Seeker47]

I have a couple of WD Passport externals that I had been accessing regularly on the computer I'm currently using, even though they are USB-3 and this computer does not have native USB-3, by means of the USB-3 to USB-2 cable that was included with the Passport HDDs. The HDDs show up by name in Win-7, but are no longer receiving a drive letter, and so are not useable. It's not the computer's USB ports: various thumbdrives continue to work fine as before. And it does not appear to be the Passport HDDs that are faulty: just connected them to a netbook that also only has USB-2, and they both are fully accessible there. I've rebooted this cube desktop a few times, but that did not improve matters. Nothing should have changed, apart from the latest round of MS security fixes. Has anyone else seen this, and does anything come to mind ?

[EDIT: O.K., I just went into "Computer Mgt." (which used to be called "Disk Manager", and is now harder to find post-XP) and manually added back the drive letter that one of the Passport HDDs used to receive automatically, as a matter of course. That seems to have worked, at least for the time being. I guess that is the most important thing, though it still begs the question as to why the automatic USB drive assignment for these particular externals went away. They clearly did not go anywhere with that netbook, which is also running Win-7, but the 32-bit variety.]

[fritzi93]

AFAIK, those Passport externals don't have a power adapter and are powered by the USB port. If that's correct, there's the cause of your problem.

[Seeker47]

AFAIK, those Passport externals don't have a power adapter and are powered by the USB port. If that's correct, there's the cause of your problem.

That's how they are sold, and intended to be used. So, at times they work, and other times not ? Or with some computers more reliably than with others ?

I'll be curious to see if that reinstating of the drive letters sticks, the next time they get connected.

[nic2k4]

USB ports are supposed to be able to supply 500 mA each, your external drive may require a little over that at startup. Most of the time the port may be able to supply over 500 mA for a short time, but with time it's possible the drive power requirement increased and the motherboard can't keep up. Use a USB Y cable to collect power from 2 ports making 1 Amp available for the drive. BTW, plug the cable into the drive last.

[aedipuss]

You could try getting an ac powered usb hub and connecting them there. My usb keyboard with led lights acts up sporadically and needs to be moved to another port.

[TreeTops]

I second aedipuss's recommendation. I had problems with my external passport that was solved by a ac powered usb hub. Bought the hub at Walmart 4 years ago and it's still powering the passport with no issues.

[Seeker47]

Good suggestions. I don't have the Y cable, but will get one. Probably have a powered hub around here -- somewhere -- though it is not something I've had much need for, until now. Odd how that little netbook seems to be able to run these Passports, without any "help." (It only has two ports, though, while the XPC has at least six.)

[Seeker47]

USB ports are supposed to be able to supply 500 mA each, your external drive may require a little over that at startup. Most of the time the port may be able to supply over 500 mA for a short time, but with time it's possible the drive power requirement increased and the motherboard can't keep up. Use a USB Y cable to collect power from 2 ports making 1 Amp available for the drive. BTW, plug the cable into the drive last.

One apparent hole in this theory, though: it seems like the Passport is usually being detected (as shown by "Open Devices & Printers" Systray icon, where you go to release an attached USB device in Win-7); it just isn't automatically getting the drive letter anymore. If I go into "Disk Management" I can still see it, and manually assign it the drive letter. From there I can use the Passport normally . . . at least until the next reboot.

[turk690]

AFAIK, those Passport externals don't have a power adapter and are powered by the USB port. If that's correct, there's the cause of your problem.

That's how they are sold, and intended to be used. So, at times they work, and other times not ? Or with some computers more reliably than with others ?

I'll be curious to see if that reinstating of the drive letters sticks, the next time they get connected.

All other conditions being ideal, the other difference of USB3 compared with USB2 other than higher data transfer rates is that USB3 is allowed a maximum of 900mA. USB2 ports are current-limited to 500mA, as said earlier. WD passports are still current-hungry HDD devices and possibly took advantage of the higher current available through a USB3 port, that's why they are specified to be used for USB3 (they may be consuming close to 500mA, marginal by USB2 standards); connecting them to a USB2 port can equally succeed or fail.
These external HDDs will also have internal DC-DC inverters to convert the +5Vdc taken from the USB power lines to other voltages required. This circuitry will have electrolytic capacitors, which can be considered an Achilles heel of all modern electronic equipment, and slowly dry out or blow up, unnecessarily increasing the current required and making the voltages fluctuate. This compounds the already marginal situation of connecting a power-requiring USB3 device to a USB2 port.
A series of checks and handshakes are performed by Windows whenever a USB device is introduced into a computer before a drive letter is issued. Somewhere in the process, these fluctuations are enough to end in corrupt data transfers. No drive letter.

[Seeker47]

AFAIK, those Passport externals don't have a power adapter and are powered by the USB port. If that's correct, there's the cause of your problem.

That's how they are sold, and intended to be used. So, at times they work, and other times not ? Or with some computers more reliably than with others ?

I'll be curious to see if that reinstating of the drive letters sticks, the next time they get connected.

All other conditions being ideal, the other difference of USB3 compared with USB2 other than higher data transfer rates is that USB3 is allowed a maximum of 900mA. USB2 ports are current-limited to 500mA, as said earlier. WD passports are still current-hungry HDD devices and possibly took advantage of the higher current available through a USB3 port, that's why they are specified to be used for USB3 (they may be consuming close to 500mA, marginal by USB2 standards); connecting them to a USB2 port can equally succeed or fail.
These external HDDs will also have internal DC-DC inverters to convert the +5Vdc taken from the USB power lines to other voltages required. This circuitry will have electrolytic capacitors, which can be considered an Achilles heel of all modern electronic equipment, and slowly dry out or blow up, unnecessarily increasing the current required and making the voltages fluctuate. This compounds the already marginal situation of connecting a power-requiring USB3 device to a USB2 port.
A series of checks and handshakes are performed by Windows whenever a USB device is introduced into a computer before a drive letter is issued. Somewhere in the process, these fluctuations are enough to end in corrupt data transfers. No drive letter.

Interesting. This might also explain why my earlier, strictly USB-2 WD Passport or Elements models don't seem to have had this problem. (I do tend to do a File Compare / Verify after backing up something important to the USB-3 Passports.)

My takeaway from your reply:

1. Perhaps I'd better make use of the powered hub I just picked up, when using these drives. {*}

2. Considering what you wrote about capacitors going bad, maybe these drives are not the best
choice for important backups storage. Unfortunately, they are what's available or dominant in
the market now, particularly at >500 Gb. capacities, so our options are limited. I am not going
to change my computers, just to get built-in USB-3 ports. My first experiment with a USB-3
controller card, which was based on an NEC chipset, failed due to compatibility issues. Other
such cards from other mfr.s that I've seen online appear suspiciously identical, with some
listing the same chipset.

[ * Oddly enough, in spite of their truly vast selection, Fry's stocked almost nothing in the way of a USB Y-cable. Maybe their online version does. I guess I would need one with a USB-3 connector at one end, branching out to two standard USB-2 connectors.]