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- HDD no longer recognized.
- Peter Jason
March 29, 2014, 4:15 am
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Re: HDD no longer recognized.
OK, is it a USB drive ?
I wish these things had a monitor LED for
the +5V power rail, as seen at the drive end...
It would make answering this question a whole
When the resettable Polyfuse opens, it takes
a couple minutes for it to re-crystallize and
start conducting again, when the overload goes away.
If the USB hard drive does not respond the first
time, disconnect it, wait two minutes, then plug it
in and try again.
If the problem persists, use a hydra cable with two USB
on one end of the cable. The flavor of hydra to use,
depends on whether your USB drive enclosure has a barrel
power connector input or not. Using a hydra cable, is
intended to bypass this "shortage of power" issue.
The drive is only short of power for the first
ten seconds of operation. If it manages to spin up
and not blow the Polyfuse, then it'll continue
to stay running. As the startup current is 1 ampere,
and the steady current is around 0.25 ampere or so.
The current drops after it starts up successfully,
and the fuse can cool off a bit.
The Polyfuse resets itself - there is no "cartridge" to
change or replace. Polyfuses are normally pretty good, in terms
of not blowing out forever. Let them cool off for two
minutes, then try them again. Simply removing the
USB connector, is sufficient to allow them to cool off.
There is no need to shut off the computer to encourage
cooling. Just remove the electrical load on the port.
Your motherboard has Polyfuses on:
1) PS/2 mouse and keyboard connector
2) Parallel port connector
3) USB2 and USB3 ports (different sized fuse for each)
The cooling fans are not fused.
The PC beep speaker is not fused. Pinching the +5V wire
of the PC beep speaker, until it shorts against the chassis
ground, causes the speaker wire to glow red-hot :-) Asking the
question, what were those engineers thinking :-) Of course
pinching the wire is a dumb thing to do, but still, the
user must be protected from such.
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