USB Hub Power Supply Causing Huge Problem!

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fine-tune
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USB Hub Power Supply Causing Huge Problem!

Post by fine-tune » Wed Dec 14, 2016 9:38 pm

I apologize for this lengthy post. An uncommon problem requires a lengthy explanation.


My best friend of 30 years teaches english literature at a local college. He likes to read books and
newspapers. He must use computers and cell phones, but he would rather not! His home office
desktop was built by me about one year ago.

All of us have heard the expression, "no good deed goes unpunished." I'm afraid that's what happened
to me. I purchased two dozen very rugged portable hubs for my business. The case is 1/8" aluminum
with rock solid ports. Most portable hubs are junk plastic with awful ports.

I gave a hub and switching wall-wart power supply to my friend. (See attached images.) A couple of
days ago he called and said his desktop was dead. He had connected the hub and plugged in the wall-wart.

I pulled the desktop power supply and tested it in my shop. It was definitely dead. I purchased another
identical unit. I unplugged all peripherals from the desktop before pressing the power switch. It started
instantly and the operating system was undamaged.

I powered down the desktop and connected an AIO printer. The desktop was shutdown each time I connected
another peripheral. A tedious process, but it was the safest way to test each device. The last thing I connected
was the hub and its wall-wart switcher. The brand new desktop power supply would not start! I immediately
unplugged the wall-wart from the hub. Fortunately, no harm was done. The desktop started normally again.

I load tested the 2000ma wall-wart in my shop. Tested good. The same hub and wall-wart was plugged into
three desktops and three laptops at my business. In all cases it worked perfectly!

I gave my friend another brand new hub and wall-wart. The same thing happened. His desktop would not
start until he unplugged the hub's power supply. I ran a 12 gauge extension cord out of my friend's home
office and connected it to another surge protected outlet. The wall-wart was plugged into the extension
cord, which is completely isolated from the office. Nothing changed. The desktop power supply simply
will not start if the hub wall-wart is connected.

All decent quality linear and switching power supplies have protection circuitry that will shut the unit down
if it runs too hot or is shorted at the input or output. The question is, why would a hub wall-wart (that tested
good on my bench) prevent a desktop from starting?

Guys, I've never had a problem like this before. I don't have the time to test all desktop components, even though
I built the darn thing! If you have the answer, please tell me. I feel really bad that something I gave to my best
friend caused so much trouble.
Attachments
Hub Wall-Wart.jpg
7-Port Aluminum USB Hub.jpg
7-Port Aluminum USB Hub.jpg (5.39 KiB) Viewed 3400 times

JerryR
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Re: USB Hub Power Supply Causing Huge Problem!

Post by JerryR » Thu Dec 15, 2016 7:20 am

Ran into the same (almost) problem awhile back, in that the pc refused to re-boot while the powered usb hub was connnected, but in my case the power supply was fine. (everything was working OK prior to the re-boot while the pc was runing and the hub was connected).
In my case the solution was to build a small adapter (to go between the pc and the hub) usb male to usb female pin to pin exept for the +5v lead.
This leaves the hub ports powered but prevent the +5v from feeding the pc usb port.
HTH
JerryR
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Janitor Tzap
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Re: USB Hub Power Supply Causing Huge Problem!

Post by Janitor Tzap » Thu Dec 15, 2016 11:17 am

Sounds more like an issue with the USB Ports on the Mother Board.

Can you post the make and model of the Mother Board?

Also......

There have been problems with some USB Ports from certain Manufacturers.
But this has been a firmware issue.


But I'd check each USB Port on the Mother Board.
And USB Ports that are connected to a Pin Head on the Mother Board.
{Make sure you didn't get the wiring crossed.}
Image
Make sure the Grounds are not floating.
Check the mounting screws of the Mother Board.
These are normally GND points for the Mother Board.
Make sure they are down snug.

Signed: Janitor Tzap

JerryR
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Re: USB Hub Power Supply Causing Huge Problem!

Post by JerryR » Thu Dec 15, 2016 2:24 pm

Motherboard is: ASUS Z170K, USB ports are part of the MB(not headers), and all mounting screws are snug.
I first ran into this about 6 month ago, what led me to the powered hub was, when I opened the case **with the power cable removed**, there are some LEDs under the MB -(I don't use them and they are turned off in the bios) and they were glowing!
scared the daylights out of me, I thought that there was a fire under the MB.
When I unpluged the hub they turned off.
I attributed the problem to the cheap powered hub.
I understand that with passive hubs the input must get +5v from the pc and distribute it to the output ports, but I see no reason why in a powered hub the input port should inject +5v back to the pc. A low Vf diode in the +5v line could accomplish that.
JerryR
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fine-tune
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Re: USB Hub Power Supply Causing Huge Problem!

Post by fine-tune » Thu Dec 15, 2016 5:04 pm

JerryR, I haven't tried anything yet, but I think you've got the solution!

I'm a little confused about a how you constructed an adapter. There are M-to-F and F-to-M adapters.
Adapters are monolithic blobs of plastic and metal. How can you cut the +5v connection without destroying
one of the adapters?

Wouldn't it be easier to use a 6 inch (see image) extension cable? Just carefully cut away a small slice of
the insulating jacket and snip the red wire. The 5vdc from the wall-wart would no longer feed into the PC's
USB port. Is that ok with you?

JerryR, I'd like to try your adapter idea. If you can attach a picture of the adapter you constructed, or find
some images on the web that would be very helpful. Without cutting a wire (like the 6 inch extension) it's hard
for me to imagine how you blocked the +5v inside an adapter.

Janitor Tzap, you're on the right track. It could be the USB ports on the motherboard. I can think of a dozen
other scary things that might cause a short, which would trigger the protection circuitry in the desktop power
supply.

My friend tells me that since I replaced the power supply everything appears to be working normally. If there
is a problem, I'm hoping the adapter idea from JerryR is the solution. If the adapter does the job as a workaround,
I don't have to waste hours checking for intermittent shorts that are almost impossible to find.
Attachments
6 inch Extension Cable.jpg
6 inch Extension Cable.jpg (5.68 KiB) Viewed 3379 times

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Janitor Tzap
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Re: USB Hub Power Supply Causing Huge Problem!

Post by Janitor Tzap » Thu Dec 15, 2016 6:09 pm

Here's a simple powered Hub Diagram.
Image

The only thing I can think of other than a shorting USB connector.
Would be the Isolation Diode on the 5V line is breaking down, and shorting.


Signed: Janitor Tzap

JerryR
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Re: USB Hub Power Supply Causing Huge Problem!

Post by JerryR » Fri Dec 16, 2016 6:13 am

fine-tune wrote:JerryR, I haven't tried anything yet, but I think you've got the solution!

I'm a little confused about a how you constructed an adapter. There are M-to-F and F-to-M adapters.
Adapters are monolithic blobs of plastic and metal. How can you cut the +5v connection without destroying
one of the adapters?

Wouldn't it be easier to use a 6 inch (see image) extension cable? Just carefully cut away a small slice of
the insulating jacket and snip the red wire. The 5vdc from the wall-wart would no longer feed into the PC's
USB port. Is that ok with you?

JerryR, I'd like to try your adapter idea. If you can attach a picture of the adapter you constructed, or find
some images on the web that would be very helpful. Without cuting a wire (like the 6 inch extension) it's hard
for me to imagine how you blocked the +5v inside an adapter.

Janitor Tzap, you're on the right track. It could be the USB ports on the motherboard. I can think of a dozen
other scary things that might cause a short, which would trigger the protection circuitry in the desktop power
supply.

My friend tells me that since I replaced the power supply everything appears to be working normally. If there
is a problem, I'm hoping the adapter idea from JerryR is the solution. If the adapter does the job as a workaround,
I don't have to waste hours checking for intermittent shorts that are almost impossible to find.
Fine-tune.
Yes, you could use a short f-m adapter(extension) cable and snip the +5v wire. That is essentially what I did with the adapter.
The reasons I made an adapter are:
1. Didn't have a a USB extension that I could cut the 5v wire. (Personally, I hate to destroy a working device, even a cable).
2. I had a salvaged female USB/A pc board connector and a salvaged USB B type connector with about 6" of pigtails.(my hub uses USB/A to a USB/B cable)
I soldered the female USB on a pref board, and wired the USB/B pigtails pin to pin except for the + 5v wire.
HTH
JerryR
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haklesup
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Re: USB Hub Power Supply Causing Huge Problem!

Post by haklesup » Fri Dec 16, 2016 12:25 pm

pick up one of these and at least you will have an easier time confirming the supply voltage and current load for any USB device including the hub.

http://www.ebay.com/itm/USB-Charger-Doc ... SwqfNXnrJE

http://www.ebay.com/itm/LCD-USB-Detecto ... SwNRdX2OzR

http://www.ebay.com/itm/USB-Charger-Doc ... SwiONYPNmc

Search on USB Current meter and you will find many more with slightly varying features, configurations and colors. Super cheap, but shipping will take a couple weeks.

fine-tune
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Re: USB Hub Power Supply Causing Huge Problem!

Post by fine-tune » Fri Dec 16, 2016 7:00 pm

JerryR, your adapter idea worked!!

The shortest USB extension cables I have in my shop are 24 inches, so I used one just to test the idea. I cut away
about 1 inch of the insulating jacket. Cut the coaxial drain wires and peeled off the foil shield. After snipping
the +5v (red) wire I sealed the cut ends with silicone adhesive. I used 3M copper foil tape to restore the shield.
Finally, I restored the jacket with common vinyl electrical tape.

The desktop power supply started normally. After the system finished loading I opened Device Manager. Instead of
showing a "Generic USB Hub" it was listed as an "Unknown Device." There are commands to manually or force install
drivers. Sometimes one or two reboots fixes problems, so that's what I tried. It worked!

To test the hub and wall-wart I grabbed four USB sticks and plugged them into the hub in rapid succession. All four
loaded smoothly. No problems!

I'm a fanatic about system backups. Before leaving my friend's house, I made two complete image backups of his system.
In case his system screws up and again shows the hub as an "Unknown Device," it can be quickly restored from the
images.

Thank you JerryR, Janitor Tzap, and haklesup.

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Janitor Tzap
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Re: USB Hub Power Supply Causing Huge Problem!

Post by Janitor Tzap » Sat Dec 17, 2016 8:58 am

Cool, :cool:
Good job.

But I'm a little curious as to what the Wattage of the PC Power Supply is?

My reason is that, without the External Power Supply connected to the USB Hub.
Would the Hub have enough power with just the PC's Power Supply?

Many of the newer computer PSU's have increased the amperage on the +5V USB Sockets.
Because people are connecting more power hungry devices, like Hard Drives that use only the +5V off the USB Ports.

I been looking at some of the powered Hub circuits.
The Isolation Diode on the 5V line is only rated for 2 Amps.
Thus, if the amperage on the USB +5V line from the Mother Board is over the diodes rating.
You'd damage the diode causing, the PSU to be damaged, or cause safety shut down to kick in.
When you have the External Power Supply connected to the USB Hub.


Signed: Janitor Tzap

dyarker
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Re: USB Hub Power Supply Causing Huge Problem!

Post by dyarker » Sun Dec 18, 2016 6:13 am

Cutting the +5 wire in the cable from PC USB Port to the USB Hub means the PC now supplies zero power to the Hub. More important no power can flow back from hub to PC messing with sensors in PC power supply.

Depends on type of USB device(s) plugged into hub. If I remember correctly, a USB port may supply upto 500mA. If power was just from PC (unpowered hub), then 5 devices on hub could get 100mA each. With power supply on hub then each hub port may supply 500mA to each device, with zero from PC.

I may have the 500mA amount wrong, but method of operation is right.

The PC in first post probably has a bad power control chip on USP port, allowing power flow the wrong direction and messing with PC power supply. Opening +5V wire prevents back-flow, but interfered with power-on handshake between USB control chips in the PC and the hub. So a temporary "unknown device".

Cheers,
Dale Y

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