wrote:
On 28 Dec 2019 18:05:17 GMT, KenK wrote:

Paul in Houston TX wrote in
:

KenK wrote:
I used a Seagate Expension Portable Drive on my XP for years with no
problem. Then one morning it failed to work. Tried it in another
connector for my working flashdrive. Didn't work there either. It
appears on the drive list momentarily when I plug it in, then
disappears.

I tried it in another XP machine and it works fine.

Guesses? Suggestions? I'd like to get it working again rather than
the expense of buying another drive and copying all the desired files
to it. And another drive may not work either.

TIA
What powers the drive?


The USB connector supplies power.

Does the cable have two "A" connectors on one end? If so plug both in
or use a cable that does., That is to get you some extra power. Paul
might be on the right track. A powered hub is another thing to try.

I would interpret this, as the Polyfuse getting a bit
weak in the conducting (solid) state. And opening before
it was intended to open (liquid state). Polyfuses are
a recoverable fuse, that (mostly) recovers its composure
after an overload is removed. The more times it's forced
to open, the more cranky it gets.

The USB stacks each have a fuse. One fuse is shared with
two connectors. On a desktop, you can select a connector from
each stack, so that two fuses are placed in parallel.
The circuit, as drawn this way, encourages "current hogging"
so the current flows do not "nicely split" and half the
load goes on one fuse and half on the other. The concept
at work here is, the drive needs 1 amp for ten seconds,
and the second fuse "is a shoulder to cry on", and does
not necessarily share the load equally. All that the
second fuse has to do is "help a little bit not a lot".
Thus, with the two fuses in parallel, and a moderate
amount of current hogging (one fuse not helping as much
as its mate), they will limp by and provide the 1 ampere
needed. Once the drive spins up and returned to
idle level, the load drops to an insignificant level.

+5V --- fuse ---------------------+
|
+5V --- fuse ---+ |
1.1A | +----+ | +----+
+---| | +---| |
| +----+ | +----+
| |
| +----+ | +----+
+---| | +---| |
+----+ +----+
\ /
\ /
\ /
+-----------------+
| |
| 2.5" hard drive |
| with two |
| connectors |
+-----------------+

Not all drives have proper provisions for this.
Some portable drives have a "barrel input" as
well as a USB connector input. The Hydra cables
you can buy, one format of Hydra assembly, is
to have a barrel connector on the drive end, as
well as a USB connector. And the cable harness
is then "correct for the application".

You are already using a USB to USB cable, so that
provides half the power. Then, if the drive housing
has a barrel input, you select one of these. There
are at least 15 different barrel types, but for
computers and cases like this, there are likely only
2 barrels in circulation. This one is an M barrel.
On a really thin casing (a USB enclosure with a 7mm
drive), they may be tempted to use the "thinner" barrel.
The USB end, only the VBUS and GND pins are used, and
the D+ and D- are unused. It's just a "power cable".

https://www.newegg.com/black-startec...82E16812200699

Your WinXP machine *can* provide the current,
as long as the spindle on the drive isn't stuck
inside. Spindle failure happens when the FDB motor
leaks out the two drops of oil and the bearing is
dry. The spindle locks up like a son of a bitch
when dry, and a piddly little current flow won't
make it spin, ever again. But dried out motors
don't happen as much as they used to.

As long as the WinXP is a desktop and has two stacks,
you can gain the benefit of two fuses in parallel.

On a laptop, the situation varies a bit. Instead
of Polyfuses, they use silicon fuses (8 pin chip with
MOSFET pass transistor). Silicon fuses will work
nicely in a hot environment, while Polyfuses won't.
Silicon ones cut off much more sharply, and even if you plug
the Hydra into the left side and the right side of
the laptop, if there is even a hint of current hogging
(fuses not sharing the load nicely), the thing will
stop again. Laptops are much more stingy with power.
Intel says not to do that, in their application note
on the subject, but not all designers can read.

Paul