USB device shuts down PC

In article ,
says...
It seems like we're flogging a dead horse here. It's been 3 days
since the original post, and the OP has not responded with any
further information. If the PC shuts down, but could be restarted
with the front panel button without cycling the rear PSU switch,
then the +5v STBY has not tripped off, as it is needed to start the
system. That's the kind of info we're lacking about this problem.


I've got time to flog a dead horse.

--
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(remove 999 for proper email address)

"Leythos" wrote in message
om...
In article ,
says...
It seems like we're flogging a dead horse here. It's been 3 days
since the original post, and the OP has not responded with any
further information. If the PC shuts down, but could be restarted
with the front panel button without cycling the rear PSU switch,
then the +5v STBY has not tripped off, as it is needed to start the
system. That's the kind of info we're lacking about this problem.


I've got time to flog a dead horse.

--
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(remove 999 for proper email address)

Besides, they're the best ones to flog; they don't kick.

"Leythos" wrote in message
om...
In article ,
says...
It seems like we're flogging a dead horse here. It's been 3 days
since the original post, and the OP has not responded with any
further information. If the PC shuts down, but could be restarted
with the front panel button without cycling the rear PSU switch,
then the +5v STBY has not tripped off, as it is needed to start the
system. That's the kind of info we're lacking about this problem.


I've got time to flog a dead horse.

--
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(remove 999 for proper email address)

Besides, they're the best ones to flog; they don't kick.

bg - if connectors caused a short, well, USB functions then report
that short as a "power surge" and disable that USB port. Nothing in a
normal USB port (if provided sufficient voltage) can crash the OS.

Plugging in a usb device would cause the computer to reset. Even with
extreme care to insert it straight in, I got a reset. I had a spare set of
connectors with the cable for an ASUS so I just swapped it, and all was
fine. I didn't bother to troubleshoot it any further.
The op said his usb worked ok when he used an extension cable. This sounds
very similiar to what I experienced.

bg - if connectors caused a short, well, USB functions then report
that short as a "power surge" and disable that USB port. Nothing in a
normal USB port (if provided sufficient voltage) can crash the OS.

Plugging in a usb device would cause the computer to reset. Even with
extreme care to insert it straight in, I got a reset. I had a spare set of
connectors with the cable for an ASUS so I just swapped it, and all was
fine. I didn't bother to troubleshoot it any further.
The op said his usb worked ok when he used an extension cable. This sounds
very similiar to what I experienced.

bg wrote:
bg - if connectors caused a short, well, USB functions then report
that short as a "power surge" and disable that USB port. Nothing in a
normal USB port (if provided sufficient voltage) can crash the OS.

Plugging in a usb device would cause the computer to reset. Even with
extreme care to insert it straight in, I got a reset. I had a spare set of
connectors with the cable for an ASUS so I just swapped it, and all was
fine. I didn't bother to troubleshoot it any further.
The op said his usb worked ok when he used an extension cable. This sounds
very similiar to what I experienced.


To analyze this problem, you'd want

1) A storage oscilloscope, connected to +5VSB (assuming +5VSB
powers the USB port).

2) Start trace, just as the USB device is plugged in. Set the trigger
condition, on a dip in the voltage. Even under normal circumstances,
the USB bus voltage dips when a USB device is plugged in.

3) Capture a second trace, where the USB device is connected
by means of an extension cable.

If it works with the extension cable, and fails when directly
connected, it could be that the length of cable presents
enough series resistance, to prevent a full amplitude collapse
of +5VSB. The cable is functioning as an "inrush limiter".
Inrush currents on USB, have been known to go as high as
5 amps (at one time, I had an Intel document, with an
oscilloscope picture of this).

If +5VSB is ever "flattened", that can cause the power supply to
go off. The question is, what is the mechanism - badly designed
motherboard, badly designed USB device (spec violation on insertion),
or whatever. A simple multimeter is not going to do a good job of
highlighting a transient problem. The transient could be quite
short. A Polyfuse takes time to open, so it will also
pass the transient.

If the motherboard designs had the old option, of jumper
selectable powering of the USB port, you could switch a stack
of two ports over to +5V. That is the regular supply of +5V, which
has a rating of 20 amps or more. And if that one is flattened for
some reason, the power supply won't necessarily go off. The
computer could crash, bur the fans might continue to spin.

They switched over to this "+5VSB only" philosophy a couple years
ago, and it removes a degree of control for the end user. One
of the reasons to leave some degree of control to the end user,
is to work around stupid design issues like this. That is one
of the reasons I won't buy a motherboard that doesn't allow me
to adjust Vcore or Vdimm or timing or whatever. And one reason
I cannot buy a Dell/HP/Acer/Gateway etc, because it doesn't
have enough control for me.

The thing is, if I had a problem on my current motherboard (which
has no header to choose +5V versus +5VSB), I know how to fix it.
I unsolder the Polyfuse feeding the USB dual stack. I run a lead
over to +5V, placing the Polyfuse in series with the lead. That
protects me against prolonged overcurrent conditions (i.e. a real
short and not a transient). But running from +5V, also removes the
ability of that USB device to wake the computer, which might be a
desirable feature for a USB keyboard for example.

If the symptoms weren't as stated, I would also suggest a
powered external hub as a solution. The hub would have
to "eat" the transient, which would protect the computer.
(The hub would have its own +5V @ 2A DC supply.) But since
a simple length of extension cable is fixing this,
using a powered hub is not curing anything. If the computer
was failing, even with an extension cable, then using an
external powered hub would be another way to address the
problem.

Paul

bg wrote:
bg - if connectors caused a short, well, USB functions then report
that short as a "power surge" and disable that USB port. Nothing in a
normal USB port (if provided sufficient voltage) can crash the OS.

Plugging in a usb device would cause the computer to reset. Even with
extreme care to insert it straight in, I got a reset. I had a spare set of
connectors with the cable for an ASUS so I just swapped it, and all was
fine. I didn't bother to troubleshoot it any further.
The op said his usb worked ok when he used an extension cable. This sounds
very similiar to what I experienced.


To analyze this problem, you'd want

1) A storage oscilloscope, connected to +5VSB (assuming +5VSB
powers the USB port).

2) Start trace, just as the USB device is plugged in. Set the trigger
condition, on a dip in the voltage. Even under normal circumstances,
the USB bus voltage dips when a USB device is plugged in.

3) Capture a second trace, where the USB device is connected
by means of an extension cable.

If it works with the extension cable, and fails when directly
connected, it could be that the length of cable presents
enough series resistance, to prevent a full amplitude collapse
of +5VSB. The cable is functioning as an "inrush limiter".
Inrush currents on USB, have been known to go as high as
5 amps (at one time, I had an Intel document, with an
oscilloscope picture of this).

If +5VSB is ever "flattened", that can cause the power supply to
go off. The question is, what is the mechanism - badly designed
motherboard, badly designed USB device (spec violation on insertion),
or whatever. A simple multimeter is not going to do a good job of
highlighting a transient problem. The transient could be quite
short. A Polyfuse takes time to open, so it will also
pass the transient.

If the motherboard designs had the old option, of jumper
selectable powering of the USB port, you could switch a stack
of two ports over to +5V. That is the regular supply of +5V, which
has a rating of 20 amps or more. And if that one is flattened for
some reason, the power supply won't necessarily go off. The
computer could crash, bur the fans might continue to spin.

They switched over to this "+5VSB only" philosophy a couple years
ago, and it removes a degree of control for the end user. One
of the reasons to leave some degree of control to the end user,
is to work around stupid design issues like this. That is one
of the reasons I won't buy a motherboard that doesn't allow me
to adjust Vcore or Vdimm or timing or whatever. And one reason
I cannot buy a Dell/HP/Acer/Gateway etc, because it doesn't
have enough control for me.

The thing is, if I had a problem on my current motherboard (which
has no header to choose +5V versus +5VSB), I know how to fix it.
I unsolder the Polyfuse feeding the USB dual stack. I run a lead
over to +5V, placing the Polyfuse in series with the lead. That
protects me against prolonged overcurrent conditions (i.e. a real
short and not a transient). But running from +5V, also removes the
ability of that USB device to wake the computer, which might be a
desirable feature for a USB keyboard for example.

If the symptoms weren't as stated, I would also suggest a
powered external hub as a solution. The hub would have
to "eat" the transient, which would protect the computer.
(The hub would have its own +5V @ 2A DC supply.) But since
a simple length of extension cable is fixing this,
using a powered hub is not curing anything. If the computer
was failing, even with an extension cable, then using an
external powered hub would be another way to address the
problem.

Paul

It sounds like the USB device is shorting on the case - have you checked
that none of the power cables are against the inside of the case.

Failing that as the others have said - USB devices use a specific rail
on the PSU and if you have a few USB devices - the PSU cant give enough
power and shuts down (take all un necessary USB out to rule this out)

if that then does not work - try another USB stick as yours may be
faulty


--
Dalo Harkin
Posted via http://www.computerhelpforums.net

It sounds like the USB device is shorting on the case - have you checked
that none of the power cables are against the inside of the case.

Failing that as the others have said - USB devices use a specific rail
on the PSU and if you have a few USB devices - the PSU cant give enough
power and shuts down (take all un necessary USB out to rule this out)

if that then does not work - try another USB stick as yours may be
faulty


--
Dalo Harkin
Posted via http://www.computerhelpforums.net

Paul wrote in message ...
If it works with the extension cable, and fails when directly
connected, it could be that the length of cable presents
enough series resistance, to prevent a full amplitude collapse
of +5VSB. The cable is functioning as an "inrush limiter".
Inrush currents on USB, have been known to go as high as
5 amps (at one time, I had an Intel document, with an
oscilloscope picture of this).

The cable would need two and a half ohms of resistance to limit the current
to 2 amps from the 5 volt standby.
For that much resistance, the wire gauge would need to be in the #40 AWG
range which would make it single strand and way to delicate.
For a real world extension cable using typical wire gauges, the cable would
have to be defective.
bg

Paul wrote in message ...
If it works with the extension cable, and fails when directly
connected, it could be that the length of cable presents
enough series resistance, to prevent a full amplitude collapse
of +5VSB. The cable is functioning as an "inrush limiter".
Inrush currents on USB, have been known to go as high as
5 amps (at one time, I had an Intel document, with an
oscilloscope picture of this).

The cable would need two and a half ohms of resistance to limit the current
to 2 amps from the 5 volt standby.
For that much resistance, the wire gauge would need to be in the #40 AWG
range which would make it single strand and way to delicate.
For a real world extension cable using typical wire gauges, the cable would
have to be defective.
bg

On May 21, 1:35*am, Paul wrote:
If +5VSB is ever "flattened", that can cause the power supply to
go off. The question is, what is the mechanism - badly designed
motherboard, badly designed USB device (spec violation on insertion),
or whatever. A simplemultimeteris not going to do a good job of
highlighting a transient problem. The transient could be quite
short.

A transient that short would never cause a problematic voltage
reduction. And increases wire would not avert that transient.

However the extension cord may cause a USB device to not enter High
Speed mode. +5VSB must be so low as to be defective even without the
USB device. Would still boot the computer. Would appear defective
only on the multimeter. So close to the edge that a USB device in
High Speed mode finally causes the crash.

There exists a wide area between good voltage and a crashed
computer. In that wide region is a working computer and a voltage too
low. A condtion found using a multimeter.

Again, a USB transient cannot be that fast and still crash a
computer. Extension cord wire cannot diminish that current. At least
half the posts here are immediately eliminated if simply measuring the
+5VSB with a multimeter. Without those voltage numbers, we are doing
nothing but wild speculation.

On May 21, 1:35*am, Paul wrote:
If +5VSB is ever "flattened", that can cause the power supply to
go off. The question is, what is the mechanism - badly designed
motherboard, badly designed USB device (spec violation on insertion),
or whatever. A simplemultimeteris not going to do a good job of
highlighting a transient problem. The transient could be quite
short.

A transient that short would never cause a problematic voltage
reduction. And increases wire would not avert that transient.

However the extension cord may cause a USB device to not enter High
Speed mode. +5VSB must be so low as to be defective even without the
USB device. Would still boot the computer. Would appear defective
only on the multimeter. So close to the edge that a USB device in
High Speed mode finally causes the crash.

There exists a wide area between good voltage and a crashed
computer. In that wide region is a working computer and a voltage too
low. A condtion found using a multimeter.

Again, a USB transient cannot be that fast and still crash a
computer. Extension cord wire cannot diminish that current. At least
half the posts here are immediately eliminated if simply measuring the
+5VSB with a multimeter. Without those voltage numbers, we are doing
nothing but wild speculation.

In article 855d18bf-c94c-4ffa-80cd-26dbef39a7d3
@u8g2000yqn.googlegroups.com, says...
At least
half the posts here are immediately eliminated if simply measuring the
+5VSB with a multimeter. Without those voltage numbers, we are doing
nothing but wild speculation.


And you can't measure that value without cutting into the cable/device,
since you have to measure it at the device to be sure.

A power supply is cheap, does not require any cutting, and is most
likely the cause of the problem.

--
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(remove 999 for proper email address)

In article 855d18bf-c94c-4ffa-80cd-26dbef39a7d3
@u8g2000yqn.googlegroups.com, says...
At least
half the posts here are immediately eliminated if simply measuring the
+5VSB with a multimeter. Without those voltage numbers, we are doing
nothing but wild speculation.


And you can't measure that value without cutting into the cable/device,
since you have to measure it at the device to be sure.

A power supply is cheap, does not require any cutting, and is most
likely the cause of the problem.

--
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(remove 999 for proper email address)