I found at
    http://cablesonline.com/usbdainusb.html

an inexpensive USB tester -- it's currently selling for $5! and it's already
saved me because as soon as I got it I plugged it into a known good
computer's port and then into the CPU board and it showed that one is wired
correctly and one isn't!  That's an incredible return o nmy investment since
it would have taken me at least 5-10 minutes to hack up a cable and connect
a meter.

    Norm

"Matthew Kendall" <mdkendall@hotmail.com> wrote in message> "moocowmoo"
<meltyb@hotmail.com> wrote
>
> >> Kensington sell a USB-powered LED-on-a-stick which would seem to do
> >> the job. http://www.kensington.com/html/1176.html
> >
> > That won't do the job. You'll probably wreck it with reverse polarity
> > and because it has charge storage you'd have to wait an hour for the
> > LED to go out after you disconnected it.
>
> That's interesting. I didn't think that these were anything more than an
LED
> and a resistor. What else do they have in them?
>

I reckon he's confused by the statement  'Uses less than 90 seconds of
battery charge per hour'

ie the power used by the LED in an hour is equivalent to running the laptop
for about 90 seconds. I looks to me like it's just an LED and a resistor in
some snazzy packaging. Anyone actually  taken one of these things to bits?

Richard

"moocowmoo" <meltyb@hotmail.com> wrote

>> Kensington sell a USB-powered LED-on-a-stick which would seem to do
>> the job. http://www.kensington.com/html/1176.html
>
> That won't do the job. You'll probably wreck it with reverse polarity
> and because it has charge storage you'd have to wait an hour for the
> LED to go out after you disconnected it.

That's interesting. I didn't think that these were anything more than an LED
and a resistor. What else do they have in them?

"moocowmoo" <meltyb@hotmail.com> wrote in message
news:comnj9$7nj$1$830fa795@news.demon.co.uk...
>
> > >
> > > Sure -- but without experience with that bus, I wasn't sure that this
> > > would be a "perfect" test.  If you're right -- and the next poster has
a
> > > really nice suggestion of making a test cable with LEDs (and
resistors,
> > > of course), it'll be trivial to check every board from here on out.
> >
> > Kensington sell a USB-powered LED-on-a-stick which would seem to do the
> job.
> > http://www.kensington.com/html/1176.html
> >
> >
>
> That won't do the job. You'll probably wreck it with reverse polarity and
> because it has charge storage you'd have to wait an hour for the LED to go
> out after you disconnected it.
>
> Peter

Actually, my wife has one just like that.  Thanks for the warning.

    Norm

> >
> > Sure -- but without experience with that bus, I wasn't sure that this
> > would be a "perfect" test.  If you're right -- and the next poster has a
> > really nice suggestion of making a test cable with LEDs (and resistors,
> > of course), it'll be trivial to check every board from here on out.
>
> Kensington sell a USB-powered LED-on-a-stick which would seem to do the
job.
> http://www.kensington.com/html/1176.html
>
>

That won't do the job. You'll probably wreck it with reverse polarity and
because it has charge storage you'd have to wait an hour for the LED to go
out after you disconnected it.

Peter


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"Norm Dresner" <ndrez@att.net> wrote in ...
> "Meindert Sprang" <mhsprang@NOcustomSPAMware.nl> wrote ...
> > "Norm Dresner" <ndrez@att.net> wrote ...
> > > How can I test a USB setup in a (completely) non-destructive
> > > manner? I'm more than comfortable using DVMs and even oscilloscopes
> > > but I really don't know what I can measure that will assure me that
> > > the connector is on the board correctly.
> >
> > Well, if you download the USB spec from www.usb.org, you can see which
> > contacts carry the 5V. So you can measure with a DVM whether these
> > contacts carry 5V in the right polarity. You can then safely plug in a
> > device to see if the polarity of the datalines was ok or not.
>
> Sure -- but without experience with that bus, I wasn't sure that this
> would be a "perfect" test.  If you're right -- and the next poster has a
> really nice suggestion of making a test cable with LEDs (and resistors,
> of course), it'll be trivial to check every board from here on out.

Kensington sell a USB-powered LED-on-a-stick which would seem to do the job.
http://www.kensington.com/html/1176.html

Norm Dresner wrote:
> "Trygve Selmer" <trselmer@start.no> wrote in message
> 
>>You also could buy a cable tester. This will normally test RJ-45, RJ-11
>>(phone jack) and USB. Today they are relatively cheap.
> 
> I've seen RJ-45, RJ-11, and coax testers but never noticed a USB one.  I'll
> have to check my preferred supplier's catalog again.

Mine is called Skymaster Remote Cable Tester DCJ-0102 (made in Taiwan), 
testing RJ-45, RJ-11, USB and BNC (coax).

Link to the new version of this tool:
<http://www.fonitech.com/catalog/product_info.php?cPath=57&products_id=476>

	Trygve

"Trygve Selmer" <trselmer@start.no> wrote in message
news:41AE220B.6020704@start.no...
> moocowmoo wrote:
> > "Norm Dresner" <ndrez@att.net> wrote in message
> > news:eQfrd.77850$7i4.11192@bgtnsc05-news.ops.worldnet.att.net...
> >
> >>How can I test a USB setup in a (completely) non-destructive manner?
I'm
> >>more than comfortable using DVMs and even oscilloscopes but I really
don't
> >>know what I can measure that will assure me that the connector is on the
> >>board correctly.
> >
> > I'd make a test cable. Cut up a USB cable and add some resistors and
LEDs
> > between vcc and ground. Have a GREEN led light up for a good connection
and
> > RED for bad. Then plug it into your SBC and check for a green light
before
> > you connect any USB devices.
> >
> > You can work out which pins to use on here
> > http://www.starmount.co.uk/s_usbpin.htm
>
> You also could buy a cable tester. This will normally test RJ-45, RJ-11
> (phone jack) and USB. Today they are relatively cheap.

I've seen RJ-45, RJ-11, and coax testers but never noticed a USB one.  I'll
have to check my preferred supplier's catalog again.

    Thanks much for the suggestion.

    Norm

moocowmoo wrote:
> "Norm Dresner" <ndrez@att.net> wrote in message
> news:eQfrd.77850$7i4.11192@bgtnsc05-news.ops.worldnet.att.net...
> 
>>How can I test a USB setup in a (completely) non-destructive manner?  I'm
>>more than comfortable using DVMs and even oscilloscopes but I really don't
>>know what I can measure that will assure me that the connector is on the
>>board correctly.
> 
> I'd make a test cable. Cut up a USB cable and add some resistors and LEDs
> between vcc and ground. Have a GREEN led light up for a good connection and
> RED for bad. Then plug it into your SBC and check for a green light before
> you connect any USB devices.
> 
> You can work out which pins to use on here
> http://www.starmount.co.uk/s_usbpin.htm

You also could buy a cable tester. This will normally test RJ-45, RJ-11 
(phone jack) and USB. Today they are relatively cheap.

"Meindert Sprang" <mhsprang@NOcustomSPAMware.nl> wrote in message
news:10qr4v16v7tjb2b@corp.supernews.com...
> "Norm Dresner" <ndrez@att.net> wrote in message
> news:eQfrd.77850$7i4.11192@bgtnsc05-news.ops.worldnet.att.net...
> > Okay, I admit it, I've screwed it up before and I don't want to do it
> again.
> > I have several Single Board Computers that have SBC headers on them and
I
> > have to run a commercial cable from the headers to a standard USB
chassis
> > connector.  The polarity of the USB header isn't obvious on some of
these
> > boards and I have destroyed the USB interface on one of them by plugging
a
> > device into the USB with the header on rotated 180 degrees.  I don't
want
> to
> > do this again.
> >
> > How can I test a USB setup in a (completely) non-destructive manner?
I'm
> > more than comfortable using DVMs and even oscilloscopes but I really
don't
> > know what I can measure that will assure me that the connector is on the
> > board correctly.
>
> Well, if you download the USB spec from www.usb.org, you can see which
> contacts carry the 5V. So you can measure with a DVM whether these
contacts
> carry 5V in the right polarity. You can then safely plug in a device to
see
> if the polarity of the datalines was ok or not.

    Sure -- but without experience with that bus, I wasn't sure that this
would be a "perfect" test.  If you're right -- and the next poster has a
really nice suggestion of making a test cable with LEDs (and resistors, of
course), it'll be trivial to check every board from here on out.

    Thanks
        Norm