My USB cable... overheated??

[fendel]

Anyone ever have this happen? I was having trouble with a USB device last night, and found the cable was hot to the touch.

Recently I got a case with front USB ports. They seem to work fine: WinXP recognizes my gamepad on either one. But when I plugged in the cable for my MP3 player, I got a "hardware not recognized" error, with "unknown device" showing up in Device Manager. The MP3 player software (Creative PlayCenter) didn't recognize the player as being plugged in. I tried this a few times. Then I noticed the cable was hot.

Plugged my gamepad in and left it there for a while. Room-temperature cable.

Plugged my MP3 player into the USB ports at the back of the machine. Ding, it's recognized, everything works, cable isn't hot (though it does have this barely detectable vibration thing going on).

Anyone know what caused this? Am I a fool if I keep using this cable?

 

[freebee]

Your USB cable is trying to become a "firewire".....

 

[fendel]

Heh...

Okay, seriously though...

 

[dszd0g]

The same cable works in the back and not in the front? It is hot when used on the connectors in the front of the case and not in the back?

On most mobos and cases the USB connectors on the front are wired by hand. Were you the one that wired the connections to the front of the case? I would double check those connections if I were you. I have never had a USB cable get hot on me (just tested all mine and they are room temperature). It sounds to me that there is excessive current flowing through the cable when it is plugged in to the front of the case. To me that sounds like a short or bus contention (hooking up a high and low signal to the same output and having the output float somewhere in between creating excessive current in CMOS).

I would not use the connectors on the front of the case until you are sure they are wired correctly. It is possible to melt electronics, try components, or start an electrical fire if one creates excessive current.

 

[fendel]

Exactly--the cable works in the back USB connectors but not the front ones.

I did the wiring, quintuple-checking the motherboard manual and the cryptic little scrap of information the case manufacturer provided. Guess I'd better open it up and take another look. I assumed that since the gamepad worked normally, the wiring must be okay, but maybe not...

I thought some more about the weird vibration I noted in the cable. It's a buzzy kind of feeling. Kind of like electricity produces.

:Q

 

[Bovinicus]

I suggest you just plug the devices into the back and not worry about it. =)

 

[dszd0g]

Originally posted by: fendel

I did the wiring, quintuple-checking the motherboard manual and the cryptic little scrap of information the case manufacturer provided. Guess I'd better open it up and take another look. I assumed that since the gamepad worked normally, the wiring must be okay, but maybe not...

If you've double checked it and found it fine. I would try the tech support of your mobo manufacturer and case manufacturer to make sure they did not make an error in their documentation. It is not likely, but I have seen an errata released for one recently released mobo (I forget which one). With these symptoms I can almost guarentee you it is wired wrong.

 

[DeschutesCore]

Verify the connections from the front of the case to the mobo. If you swap the +5 line with the +Data line, you can easily kill the device or board. Normal intel Spec USB is:

+5V
-Data
+Data
Ground

Sometimes there is another pin labeled shield, use the key pin for this guy. And keep in mind, some boards use a reversed or even altogether different layout.

DC

 

[DeschutesCore]

Doh, just forgot. If possible, try another cable. A shorted cable can have the same effect as a lopped battery. i.e. HEAT.

DC

 

[fendel]

Thanks, you guys. I'll be taking another look at it this weekend.

Strange thing is--
Can the cable be shorted but still work when plugged into the back USB connectors??
Can the wiring be wrong but still work OK for the gamepad??

Not rhetorical questions. I really don't know.

 

[dszd0g]

Originally posted by: fendel

Can the cable be shorted but still work when plugged into the back USB connectors??

I don't see how.

Can the wiring be wrong but still work OK for the gamepad??

Yes. For example, let's say the gamepad does not require much power at all and does not need the +5V power. It could get all the power it needs off the +Data and -Data lines. I'm not saying that is the case, but I can think of circuit examples where it would work with one device and not another.

Have you checked the connectors? Maybe there is something that is causing a short with one combination of connectors and not the other?

 

[lupohki]

Your USB cable is trying to become a "firewire".....

 

[crazychicken]

haha firewire....

anyhow, ya, first try another cable. if still same problem, contact vendor.

david

 

[zephyrprime]

It really sounds like the front port is wired wrong. A sinple check with a multimeter will get to the bottom of this. If you don't have a multimeter, you can sacrifice an LED or something to check the wiring.

 

[fendel]

Okay, I just rewired the connectors, carefully following the motherboard manual's diagram. I noticed that the plastic casing on the end of two of the wires (sorry, I don't know the terminology) was a little melted. Ground, I think. I used a different set of pins on the motherboard this time, USB3 instead of USB2, since they were easier to reach.

I tried my gamepad and MP3 player with the front USB connectors and had the same results. Gamepad worked. MP3 player wasn't recognized and the cable got hot almost immediately.

Plugged the MP3 player into the back and it worked. So it seems like it's the front connectors.

Diagram in the motherboard manual looks like:
VCC [ ][ ] VCC
-Data4 [ ][ ] -Data5
+Data4 [ ][ ] +Data5
GND [ ][ ] GND
Empty [ ][ ] OC#

Wires from the case are labeled VCC1, VCC2, Data-1, Data-2, Data+1, Data+2, Ground 1, Ground 2, and Shield. I took a guess and connected Shield to OC#. Could that be a problem? (Hate to sound like a newbie, but I don't know electrical stuff.) I followed the diagram carefully, located pin 1 correctly, etc.

I'm guessing maybe the wiring that came with the case was faulty?

 

[DeschutesCore]

VCC [ ][ ] VCC = VCC
-Data [ ][ ] -Data5 = Data-
+Data [ ][ ] +Data5 = Data+
GND [ ][ ] GND = Ground
Empty [ ][ ] OC# = Shield

You're correct, it sounds pretty hard to mess up. If possible, use zephyrprime's suggestion of an LED or multimeter to test polarity. If you can see it, look at the PCB the USB ports are attached to, see if the connection is damaged or blackened.

DC

 

[KF]

>I'm guessing maybe the wiring that came with the case was faulty?

So it seems.

OC looks like the only possible place to put the shield.

Since insulation on two pins is melted, it is logical these pins are wrong. I don't think data pins should be capable of supplying enough current to melt anything, although they could be sensitive to polarity and draw heavy current with the wrong polarity of the power supply hooked to them.

Some devices have protection against reversed polarity of the PS (especialy ones that use batteries) in the form of a diode. If polarity is reversed, the diode draws excessive current, but the device is protected from total destruction. Some USB devices do not necessarily even use the power from the USB power line.

If you hook an ordinary LED to the power line without a series resistor, it will destruct instantly, so it won't work that way as a test light.

See if the game pad works with the melted pins disconnected. If so, it has to be the disconnected pins that are wrong, and most likely reversed.

 

[dszd0g]

The amount of damage one can cause by doing this wrong may not be worth it.

Obviously you wired it wrong (or it was labeled wrong) by the fact that the wires are melting. I would not use those wires that have melted, they are a fire hazard.

I would have a friend with some electrical tech skills or even better if you have a friend that is an EE, fix it. If you don't need those front ports just disconnect them. You need someone who knows how to use a DMM and some basic electrical skills to get this right.

It really isn't worth starting an electrical fire in your computer.

 

[Intelman07]

I have the same problem with my computer! My front usb doesn't work and the same thing happens in XP. I tried reversing the connectors from my front usb to my mobo but that only got one of the two USB ports working! So I gave up! I dunno what to do!

 

[fendel]

I can do without the front ports, I guess. Although... would it still be safe to connect the gamepad to one of the front ports, since it was working fine before? Or should I just disconnect the wires and plan on using only the back USB ports?

Thanks again for all your advice, this has been a learning experience for me.

 

[KF]

Originally posted by: fendel
I can do without the front ports, I guess. Although... would it still be safe to connect the gamepad to one of the front ports, since it was working fine before? Or should I just disconnect the wires and plan on using only the back USB ports?

It appears that your MP3 player is drawing a lot of current when it is plugged in because the power leads are reversed (mislabeled). Leaving the connections the way they are is not such a great idea, in case some time in the future some one forgets and plugs something into it besides the gamepad. I always forget stuff like that. You could disconnect the wires or fix them.

I guess you know hooking anything to the miswired USB could damage it.

In case you want to try fixing it (like I would):
Because the problem hasn't killed the mp3 player yet, if you reverse the wires connected to GND and VCC on one row, it probably won't be any worse. Likely it will fix the problem.

VCC [ ][ ] VCC
-Data4 [ ][ ] -Data5
+Data4 [ ][ ] +Data5
GND [ ][ ] GND
Empty [ ][ ] OC#

To minimize confusion I would pull the wires off the side labeled with Data4 while experimenting, to eliminate one USB port and confine the problem to one socket. I would also pull the wire off OC, the shield. Things should work without the shield. A shield is to reduce electical interference, such as hearing static on the radio. Then you only have 4 wires to worry about. Since your gamepad works, most likely the data pins are correct -Data5, +Data5. That leaves VCC and GND, the power pins. Switch them. Try your gamepad first. It should be OK. If OK, try the MP3. If the cable doesn't get hot, at least the problem got better. But probably that will fix it.

You could do this safer with a multimeter, comparing a working USB socket with the faulty one. But getting contact with the socket pins is difficult the way the socket is made.

 

[dszd0g]

Originally posted by: KF

You could do this safer with a multimeter, comparing a working USB socket with the faulty one. But getting contact with the socket pins is difficult the way the socket is made.

It is not difficult at all. If you have a DMM with those large round probes (which I assume you are referring to), one just takes some 22 AWG wires and wraps them around the probes a half dozen times at the grooves and uses the wires to probe. It's not like one is taking high-speed measurements with a DMM.

 

[KF]

>It is not difficult at all. ...

Easy for you; difficult for me. I've got probes that'll fit. For really small holes, I generally use a wire with alligator clips at both ends to connect the probe and a paper clip (big or small) for this sort of thing. The 4 contacts inside the USB socket are embedded in a central white insulator and would make sliding contact with one side of the probe. They are rather small, rather close, barely visible, and barely protrude above the insulator. Actually I didn't know they were there until a few hours ago when I took a look. Watching the meter while getting good contact with the little buggers is iiffy for me. You don't want to touch the one next to it. Then the other probe would have to make firm contact at the other end of the wire too. But I don't have to do it. I have to try to explain how to fendel who doesn't have a meter, and probably doesn't want to.

I don't mean to sound picky, dszd0g.

 

[dszd0g]

O.K., easy for me. However, I wish I could show you what I mean because I am pretty sure you would say that it's easy once you saw what I meant.

To me it sounds like you are using the wrong equipment. Even a paper clip is pretty big in comparison to 22 AWG wire (0.02532"/0.644mm diameter). You say "rather small, rather close, barely visible, and barely protrude above the insulator", but they aren't very small at all in my opinion. They are about the same size as the pins on an RJ45 connector, and they are much larger than modern traces on circuit boards. I don't have a pair of calipers handy, but with my ruler they seem to be just over 1mm wide (0.04"). I poke around on circuit boards with traces on the order of 0.008" (Humor: the military supposedly likes calling it "reduced producibility" instead of expensive). Obviously, not with the technique I suggested above.

I agree with your point reguarding fendel. I told fendel to have a friend who was good at this kind of thing do it. It takes some practice and I wouldn't tell someone who has never used a DMM before to start poking around with one on their computer, that is a BAD IDEA.

 

[fendel]

Originally posted by: dszd0g
It is not difficult at all. If you have a DMM with those large round probes (which I assume you are referring to), one just takes some 22 AWG wires and wraps them around the probes a half dozen times at the grooves and uses the wires to probe. It's not like one is taking high-speed measurements with a DMM.

Wrap who in the what now? (No, no need to explain, since I don't have a meter anyhow...)

If I'm feeling brave, maybe I'll try this switch-the-VCC-and-ground-wires idea in the next couple of days... Eeep. Would that mean the case manufacturer mislabeled (and miscolored) those wires? Or is it more likely the motherboard diagram is wrong?

Man, do I wish they'd standardize this stuff so we could have a nice tidy plug instead of tiny individual wires.