Front USB connection to motherboard

[Charlie Wilkes]

I have a socket A board that I'm setting up in a salvage case... I'm
confused about the pins for the front USB connector. Here's what the
mfr. says about the pins:

1 vcc
2 data+
3 data-
4 gnd
5 gnd/nc

I'm confused because there are 9 pins. I assume the numbering goes:

1 2
3 4
5 6
7 8
K 9

Is it safe to assume the 1-4 sequence starts over with pin #5?

Here is a link to the online docs for the board:
http://www.j-mark.com/PRODUCT/mb/v4mdmp.html

Any thoughts/guidance much appreciated...

Charlie

 

[Paul]

I have a socket A board that I'm setting up in a salvage case... I'm
confused about the pins for the front USB connector. Here's what the
mfr. says about the pins:

1 vcc
2 data+
3 data-
4 gnd
5 gnd/nc

I'm confused because there are 9 pins. I assume the numbering goes:

1 2
3 4
5 6
7 8
K 9

Is it safe to assume the 1-4 sequence starts over with pin #5?

Here is a link to the online docs for the board:
http://www.j-mark.com/PRODUCT/mb/v4mdmp.html

Any thoughts/guidance much appreciated...

Charlie

Well, the first thing I don't like about their pinout, is the
data+ and data- are on the wrong pins. I checked the manual
for the motherboard of the computer I'm typing on, and it looks
like this. I've also taken the liberty of overlaying the pinout
on the 2x5 header.

/ vcc X X vcc \
USB _/ data- X X data- \_ USB
#1 \ data+ X X data+ / #2
\ gnd X X gnd /
X NC

So the 2x5 header layout, is really a couple of 1x4 layouts
side by side.

If you want to see the official Intel recommendation, check out
section 3.2.3 on PDF page 28. (Formfactors.org is an Intel site.)
It is essentially the same as my pinout above, only missing "NC".

http://www.formfactors.org/developer\specs\A2928604-005.pdf

If you are going to connect that motherboard, to a standard ATX
computer case, you'll need to swap the D+ and D- pins on each
logical 1x4 cluster. Your computer case should have a plastic
shell that holds the pins for the USB connector, and you can move
the pins from one hole to another, if you need to. An example of
how to do that, is shown here.

http://www.frontx.com/head_con.html

Some examples of various USB header patterns are shown here.
The last one on the page is really screwy, and I wish they
had mentioned which motherboard they found that on.

http://www.frontx.com/cpx108_2.html

Lastly, if you really want USB that bad, you can always plug
a PCI USB2 card into a PCI slot. That way, you don't have to
wire anything, and can just plug into the back of the machine.
If you need front access, you can use a nice powered USB2
hub, and stick it up on top of the computer, near the front.

OK, I just found a manual for your motherboard. So now you
have yet another source of info. (Jetway is a master of
disguise, and they also use the Machspeed product name.
So now I can add J-Mark to my list.)

http://download.jetway.com.tw/download.asp?sorder=Name&sword=V4MDMP

http://216.185.128.200/temp/jetway0c/downloads/manual/SHV2MDMP1A.pdf

On page 15 of SHV2MDMP1A.pdf, it shows in fact that they did
use the standard pinout. So if you believe this manual, you
don't need to swap wires. But, note that pin 9 is labelled "OC",
and that means, if there is a black wire on your computer
case wiring, corresponding to OC (pin 9), you should remove
that wire from the plastic 2x5 shell. You don't want GND
from the black computer case wire, touching the OC pin. If it
does touch, the USB port will shut off, and you'll be pestered by a
"USB overcurrent" error.

HTH,
Paul

 

[Charlie Wilkes]

http://download.jetway.com.tw/download.asp?sorder=Name&sword=V4MDMP

http://216.185.128.200/temp/jetway0c/downloads/manual/SHV2MDMP1A.pdf

On page 15 of SHV2MDMP1A.pdf, it shows in fact that they did use the
standard pinout. So if you believe this manual, you don't need to swap
wires. But, note that pin 9 is labelled "OC", and that means, if there
is a black wire on your computer case wiring, corresponding to OC (pin
9), you should remove that wire from the plastic 2x5 shell. You don't
want GND from the black computer case wire, touching the OC pin. If it
does touch, the USB port will shut off, and you'll be pestered by a "USB
overcurrent" error.

Aha! So, it looks like the pinout is conventional... and now I'm
wondering about the plug inside the case, which originally housed a
different motherboard. Here is what it looks like in terms of the color
of the wires:

RED BLACK
WHITE BLUE
GREEN YELLOW
ORANGE BROWN
(K) (NONE)

I examined the color code chart at:
http://www.usbman.com/Guides/BelkinMotherboard_cable_assembly.htm

This makes me think the case plug is set up for a pinout like this:

VCC GROUND
D- D+
D+ D-
VCC GROUND

So, I think perhaps I should rearrange the wires feeding into the plug as
follows:

RED ORANGE
WHITE YELLOW
GREEN BLUE
BROWN BLACK

What do you think? I wonder how unusual it is for mfrs. to deviate from
the standard pinout, and how much damage I'm likely to do if I get it
wrong.

Thanks for taking the time to put together a very helpful response to my
OP... having that manual will make life much easier with this project.

Charlie

 

[Paul]

Aha! So, it looks like the pinout is conventional... and now I'm
wondering about the plug inside the case, which originally housed a
different motherboard. Here is what it looks like in terms of the color
of the wires:

RED BLACK
WHITE BLUE
GREEN YELLOW
ORANGE BROWN
(K) (NONE)

I examined the color code chart at:
http://www.usbman.com/Guides/BelkinMotherboard_cable_assembly.htm

This makes me think the case plug is set up for a pinout like this:

VCC GROUND
D- D+
D+ D-
VCC GROUND

So, I think perhaps I should rearrange the wires feeding into the plug as
follows:

RED ORANGE
WHITE YELLOW
GREEN BLUE
BROWN BLACK

What do you think? I wonder how unusual it is for mfrs. to deviate from
the standard pinout, and how much damage I'm likely to do if I get it
wrong.

Thanks for taking the time to put together a very helpful response to my
OP... having that manual will make life much easier with this project.

Charlie

Arrgh!

Does the computer case come with a manual ? Is there a web site for the
case (as some manufacturers admit to the wiring, on their web site) ?

If you really need to know what goes where, with a computer case harness,
it is time to dig out the multimeter. That is what I do when I get a
new case. I use the ohms scale, touch a pin inside the front mounted
USB connector, then try touching the eight wires. At least one of those wires
should read zero ohms, and then you have a match. I do this even if the
wires have a label printed on them, because sometimes that label is
wrong.

Remember that idiots work at computer case manufacturing plants.
They've done some stupid things, because those people are metal
cutters and benders, not electrical engineers. If the case doesn't
come with documents, you are going to have to make your own
documents. I don't think I'm going to trust any of my USB
devices, to the odds that the case maker read that usbman.com
web page.

I've run into wiring errors on my Antec cases, and all the
cases are made the same way, so it isn't a one in a million
accident.

If a manufacturer provides a diagram, it at least suggests
that somebody cared enough to check. I suspect for at least
some of these manufacturers, the wiring harness comes from a
third party, and the staff at the plant are too stupid to
verify what is being shipped to them. (I.e. No quality control.)

Another thought that comes to mind - if you used the case
with a different motherboard, and the USB wiring worked
and there was no damage, then the manual for the old
motherboard contains the pinout of your cable assembly

Paul

 

[Charlie Wilkes]

Does the computer case come with a manual ? Is there a web site for the
case (as some manufacturers admit to the wiring, on their web site) ?

It's a generic case, but I think I found the main board that was formerly
in it... MSI's MS-6330. I downloaded the manual and it was pretty
sketchy, but it looks as though they use the same conventional scheme for
USB. So, the plug probably matches the pinout on the board I'm using,
despite the color discrepancies.

Mainly I'm just trying to use up some parts that seem too good for the
recycler. I'm not in a hurry, so I will examine it with a multimeter as
you suggest... but first I have to make some custom leads for my
multimeter.

Thanks for your help on this.

Charlie

 

[Charlie Wilkes]

Arrgh!

This afternoon I hooked the rig up for test purposes and the front USB
ports work just fine, with no changes needed to the plug wires.

Again, thanks for your helpful feedback and above all, for finding that
manual!

Charlie

 

[Franc Zabkar]

I have a socket A board that I'm setting up in a salvage case... I'm
confused about the pins for the front USB connector. Here's what the
mfr. says about the pins:

1 vcc
2 data+
3 data-
4 gnd
5 gnd/nc

I'm confused because there are 9 pins. I assume the numbering goes:

1 2
3 4
5 6
7 8
K 9

I see you have already solved your problem, but to find the +5V (Vcc)
and Ground pins, you could have used a multimeter to test for
continuity between each pin and the red and black wires in your PSU
harness.

- Franc Zabkar