External HDD problem

Meebers wrote:

I have a IDE WD HDD connected via a Bytec adaptor to a usb connection. This
connection works great when connected to my WinXpsp3 desktop. When I
connect it to my WinXpsp3 laptop, the drive (E:)appears and then disappears
in a loop on my laptop about every 4 seconds. All 3 usb ports on the laptop
act the same. I am wanting to use this as a destination for backup. Any
suggestions appreciated.

That is a USB bus power problem.

Based on your description, this is a 2.5" drive. The drive
draws power from the USB bus (because few enclosures include
a convenient AC-DC 5V adapter).

The drive needs 5V @ 500mA, during write. This is fine, and
the bus is rated for that amount of current.

But the other drive event of importance, is spinup. Some
drives draw as much as 5V @ 1 amp. That is too much for the
bus. The 1 amp is drawn for perhaps ten seconds, until the
drive reaches full speed.

On a desktop, the bus power is monitored by a fuse (Polyfuse).
A fuse of value slightly higher than 1 amp may be used, and
the fuse is shared by the two USB connectors in a stack. So
if you look on the back of a desktop computer, and spot
two USB connectors, one above the other, chances are, they
share a 1 amp fuse.

What that means is, the desktop is relatively generous with
power. As long as the "partner" USB connector is not similarly
loaded, you can get up to 1 amp.

And that means, there is enough power for the 2.5" drive to
spin up. The 1 amp may be drawn for the first ten seconds,
and then the current drops to 200mA, until you read or write,
in which case the current may get close to 500mA.

The case of the laptop is different. On a laptop, they may choose
to use an eight pin chip, which is a "power policeman". It senses
the current, and cuts off the port if the load becomes too great.
It can more accurately gauge the 500mA limit. So, rather than the
luxury of 1 amp shared by two ports, the laptop designer may choose
to limit each port to no more than 500mA.

Now there isn't enough current to complete spinup. The power policeman
opens the circuit, before the drive finishes spinning up. And restores
the power again, and the cycle repeats.

This can be solved with a USB Y cable.

http://www.toshibadirect.com/td/b2c...;poidC8342

The USB Y cable, has two connectors on one end. One of the connectors
is a full USB connector. It has four pins and they're all wired up.
Two pins are power, two pins are for data.

The second connector is a "power only" connector. The data pins
on the second connector are not hooked up.

You plug the two connectors, into two laptop ports. In theory, if
the current flow happened to be equally divided, it would mean you
could draw 1 amp total (500mA from each of two ports). The drive
would be able to spin up. I haven't collected enough observations
from people, to know how often the Y cable forms a practical and
sufficient solution to this "power cutoff" thing.

Some 2.5" enclosures have a small barrel connector, for a power
supply. But I don't know which of the 15+ "adaptaplugs" you'd need
for that connector, whether it is "center plus" or "center minus"
adapter type. It is probably a 5V at 1 amp or more adapter. If
you're lucky, and your enclosure has the barrel input, there is
a note in the documentation, about what adapter to use. They likely
won't give the rating, but may give a part number to purchase, to
assist with powering the drive when used with a laptop. With
an adapter present, the bus power should no longer be a limitation.

HTH,
Paul

"Paul" wrote in message
news:h3gjde$51h$

Meebers wrote:

I have a IDE WD HDD connected via a Bytec adaptor to a usb connection.
This connection works great when connected to my WinXpsp3 desktop. When
I connect it to my WinXpsp3 laptop, the drive (E:)appears and then
disappears in a loop on my laptop about every 4 seconds. All 3 usb ports
on the laptop act the same. I am wanting to use this as a destination
for backup. Any suggestions appreciated.

That is a USB bus power problem.

Based on your description, this is a 2.5" drive. The drive
draws power from the USB bus (because few enclosures include
a convenient AC-DC 5V adapter).

The drive needs 5V @ 500mA, during write. This is fine, and
the bus is rated for that amount of current.

But the other drive event of importance, is spinup. Some
drives draw as much as 5V @ 1 amp. That is too much for the
bus. The 1 amp is drawn for perhaps ten seconds, until the
drive reaches full speed.

On a desktop, the bus power is monitored by a fuse (Polyfuse).
A fuse of value slightly higher than 1 amp may be used, and
the fuse is shared by the two USB connectors in a stack. So
if you look on the back of a desktop computer, and spot
two USB connectors, one above the other, chances are, they
share a 1 amp fuse.

What that means is, the desktop is relatively generous with
power. As long as the "partner" USB connector is not similarly
loaded, you can get up to 1 amp.

And that means, there is enough power for the 2.5" drive to
spin up. The 1 amp may be drawn for the first ten seconds,
and then the current drops to 200mA, until you read or write,
in which case the current may get close to 500mA.

The case of the laptop is different. On a laptop, they may choose
to use an eight pin chip, which is a "power policeman". It senses
the current, and cuts off the port if the load becomes too great.
It can more accurately gauge the 500mA limit. So, rather than the
luxury of 1 amp shared by two ports, the laptop designer may choose
to limit each port to no more than 500mA.

Now there isn't enough current to complete spinup. The power policeman
opens the circuit, before the drive finishes spinning up. And restores
the power again, and the cycle repeats.

This can be solved with a USB Y cable.

http://www.toshibadirect.com/td/b2c...;poidC8342

The USB Y cable, has two connectors on one end. One of the connectors
is a full USB connector. It has four pins and they're all wired up.
Two pins are power, two pins are for data.

The second connector is a "power only" connector. The data pins
on the second connector are not hooked up.

You plug the two connectors, into two laptop ports. In theory, if
the current flow happened to be equally divided, it would mean you
could draw 1 amp total (500mA from each of two ports). The drive
would be able to spin up. I haven't collected enough observations
from people, to know how often the Y cable forms a practical and
sufficient solution to this "power cutoff" thing.

Some 2.5" enclosures have a small barrel connector, for a power
supply. But I don't know which of the 15+ "adaptaplugs" you'd need
for that connector, whether it is "center plus" or "center minus"
adapter type. It is probably a 5V at 1 amp or more adapter. If
you're lucky, and your enclosure has the barrel input, there is
a note in the documentation, about what adapter to use. They likely
won't give the rating, but may give a part number to purchase, to
assist with powering the drive when used with a laptop. With
an adapter present, the bus power should no longer be a limitation.

HTH,
Paul

Wowthanks Paul for your answer. The drive is 3.5" an older design (tag
says Jan 2004)and perhaps the older ones are drawing more power. The Bytec
adaptor comes with its own power supply that delivers this power via the
MOLOX? connector straight to the "power connection" on the HDD (standard 4
pin power plug), delivering 12v @ 2 amp and 5v @ 2 amps. I would think this
would minimize power in the usb connector?? Other "boxed" drives in factory
enclosures work without incident with this laptop. But you are right,
perhaps it is border line current draw causing the usb to drop connection,
reconnect and drop connection again. I really got to get this solved since
it is/was going to be used to backup an image of my laptop drive. Don't
need something flaky if something goes south. Thanks again for your
response, might look for one of those "y" connectors.

Meebers wrote:

Wowthanks Paul for your answer. The drive is 3.5" an older design (tag
says Jan 2004)and perhaps the older ones are drawing more power. The Bytec
adaptor comes with its own power supply that delivers this power via the
MOLOX? connector straight to the "power connection" on the HDD (standard 4
pin power plug), delivering 12v @ 2 amp and 5v @ 2 amps. I would think this
would minimize power in the usb connector?? Other "boxed" drives in factory
enclosures work without incident with this laptop. But you are right,
perhaps it is border line current draw causing the usb to drop connection,
reconnect and drop connection again. I really got to get this solved since
it is/was going to be used to backup an image of my laptop drive. Don't
need something flaky if something goes south. Thanks again for your
response, might look for one of those "y" connectors.

Well, that is weird. A 3.5" shouldn't have that problem. The
enclosure should be self supporting, and the USB loading
should not be significant.

Is the laptop running on batteries, or on AC ?

If you insert other kinds of USB devices to the laptop,
do they have a problem ?

Are there currently any other devices connected to the
laptop at the same time as the hard drive ? Like
perhaps a USB scanner ? Or an Alcatel ADSL modem ?
Try disconnecting everything, so that the USB
hard drive, is the only connected USB item.

It could also be a software problem. Try looking in
"setupapi.log" file, and see if there is anything
interesting near the end of the file.

Paul

"Meebers" wrote in message
news:4a5bc8b2$0$5642$

I have a IDE WD HDD connected via a Bytec adaptor to a usb connection.
This connection works great when connected to my WinXpsp3 desktop. When I
connect it to my WinXpsp3 laptop, the drive (E:)appears and then disappears
in a loop on my laptop about every 4 seconds. All 3 usb ports on the
laptop act the same. I am wanting to use this as a destination for backup.
Any suggestions appreciated.

Do you by any chance have a Hewlett Packard printer?

If so, that is most likely the cause of your problem. Hewlett Packard have
just about the most convoluted driver and install arrangement in the known
universe. HP printers invariably cause side effects in Windows XP, the most
common being to disable the ability of installer software from running (thus
preventing you from installing some applications).

Another known side effect is to cause external devices to continually appear
to connect and disconnect on a regular cycle (though not the printer
itself). The worst example of this that I have seen is a flash card reader,
an external disc drive (USB like yours) and a scanner continually connecting
and disconnecting on a regular 12 second cycle (but not all at the same
time).

Uninstalling the HP printer does not solve the problem, the only solution is
to restore a backup of the operating system from before the installation of
the printer.

"Meebers" wrote in message
news:4a5bdbb1$0$5668$

"Paul" wrote in message
news:h3gjde$51h$

Meebers wrote:

I have a IDE WD HDD connected via a Bytec adaptor to a usb connection.
This connection works great when connected to my WinXpsp3 desktop. When
I connect it to my WinXpsp3 laptop, the drive (E:)appears and then
disappears in a loop on my laptop about every 4 seconds. All 3 usb
ports on the laptop act the same. I am wanting to use this as a
destination for backup. Any suggestions appreciated.

That is a USB bus power problem.

Based on your description, this is a 2.5" drive. The drive
draws power from the USB bus (because few enclosures include
a convenient AC-DC 5V adapter).

The drive needs 5V @ 500mA, during write. This is fine, and
the bus is rated for that amount of current.

But the other drive event of importance, is spinup. Some
drives draw as much as 5V @ 1 amp. That is too much for the
bus. The 1 amp is drawn for perhaps ten seconds, until the
drive reaches full speed.

On a desktop, the bus power is monitored by a fuse (Polyfuse).
A fuse of value slightly higher than 1 amp may be used, and
the fuse is shared by the two USB connectors in a stack. So
if you look on the back of a desktop computer, and spot
two USB connectors, one above the other, chances are, they
share a 1 amp fuse.

What that means is, the desktop is relatively generous with
power. As long as the "partner" USB connector is not similarly
loaded, you can get up to 1 amp.

And that means, there is enough power for the 2.5" drive to
spin up. The 1 amp may be drawn for the first ten seconds,
and then the current drops to 200mA, until you read or write,
in which case the current may get close to 500mA.

The case of the laptop is different. On a laptop, they may choose
to use an eight pin chip, which is a "power policeman". It senses
the current, and cuts off the port if the load becomes too great.
It can more accurately gauge the 500mA limit. So, rather than the
luxury of 1 amp shared by two ports, the laptop designer may choose
to limit each port to no more than 500mA.

Now there isn't enough current to complete spinup. The power policeman
opens the circuit, before the drive finishes spinning up. And restores
the power again, and the cycle repeats.

This can be solved with a USB Y cable.

http://www.toshibadirect.com/td/b2c...;poidC8342

The USB Y cable, has two connectors on one end. One of the connectors
is a full USB connector. It has four pins and they're all wired up.
Two pins are power, two pins are for data.

The second connector is a "power only" connector. The data pins
on the second connector are not hooked up.

You plug the two connectors, into two laptop ports. In theory, if
the current flow happened to be equally divided, it would mean you
could draw 1 amp total (500mA from each of two ports). The drive
would be able to spin up. I haven't collected enough observations
from people, to know how often the Y cable forms a practical and
sufficient solution to this "power cutoff" thing.

Some 2.5" enclosures have a small barrel connector, for a power
supply. But I don't know which of the 15+ "adaptaplugs" you'd need
for that connector, whether it is "center plus" or "center minus"
adapter type. It is probably a 5V at 1 amp or more adapter. If
you're lucky, and your enclosure has the barrel input, there is
a note in the documentation, about what adapter to use. They likely
won't give the rating, but may give a part number to purchase, to
assist with powering the drive when used with a laptop. With
an adapter present, the bus power should no longer be a limitation.

HTH,
Paul

Wowthanks Paul for your answer. The drive is 3.5" an older design
(tag says Jan 2004)and perhaps the older ones are drawing more power. The
Bytec adaptor comes with its own power supply that delivers this power via
the MOLOX? connector straight to the "power connection" on the HDD
(standard 4 pin power plug), delivering 12v @ 2 amp and 5v @ 2 amps. I
would think this would minimize power in the usb connector?? Other
"boxed" drives in factory enclosures work without incident with this
laptop. But you are right, perhaps it is border line current draw causing
the usb to drop connection, reconnect and drop connection again. I really
got to get this solved since it is/was going to be used to backup an image
of my laptop drive. Don't need something flaky if something goes south.
Thanks again for your response, might look for one of those "y"
connectors.

All ide hard drives receive their power from their onboard MOLEX connector.
The MOLEX connector has 4 pins. This doesn't matter if the power is sourced
from an external enclosure's power supply, or the USB line itself. In your
case, its the enclosure providing the power to the hard drive you're talking
about.

Entirely separate from that are the data lines for the ide hard drive. This
comes and goes via a 40 pin connector on the ide hard drive. In your case,
the USB data lines are connected to the enclosure. The enclosure decodes
this data for the 40 pin data cable. The data cable may have 80 wires, but
still only has 40 pins.

The only thing you haven't mentioned in the scheme in comparison between
operational on the PC, and intermittent detection and drop on the laptop, is
the USB cable itself. Is it the same cable?
Are both PC and laptop using USB 2.0 and a corresponding cable to handle
that?
Have you checked the USB ports and cable connectors for dust, dirt, and
other stuff?
Unlikely, but, have you tried reseating the 40 pin cable connector on the
enclosure's ide hard drive while powered off?
Dave