Visit http://www.meltybrain.org/1394 for more information about this wiring defect, including detailed pictures and full references to the IEEE 1394 specification.
Here's what happened:
On March 22, my wife and I both purchased new Thermaltake Xaser III cases for our new Asus A7N8X mainboards from FunKey Computers in Bellevue, Washington. We finished building these systems about 1 week later but hadn't had a chance to fully utilize all of the features on the case (including the top 1394 socket) until the evening of April 16, 2003.
My wife attached her Creative Nomad Jukebox III to the top 1394 socket using a 6-Pin to 4-Pin 1394 cable and it wouldn't enumerate. I then tried to use my Xaser III’s 1394 socket as well, and it also didn't work. I tried to use one of my 1394 portable hard drives -- It never powered up. We turned off both of our machines and each attempted to locate the problem, because we were both completely certain we connected the case and connector wires correctly. We verified that the 1394 socket VP, VG, TPA+/-, and TPB+/- pins were connected to the correct pins on the mainboard per the owner's manuals for both the case and the motherboard. We turned on our machines and continued to troubleshoot the problem. After a while, I decided to test my portable 1394 hard drive in another computer. The drive would not energize (it's powered by the 1394 bus) and would not operate and appeared to be completely dead. I then started to suspect a 1394 power problem, but the other port off the mainboard was working fine (the A7N8X board has 2 1394 ports).
At this point, we identified the 1394 chip on our A7N8X mainboards (Realtek RTL8801), and physically examined the chip on my wife's machine. It was too hot to touch. I then immediately shut off power to both of our machines and started looking for a short on the 1394 bus. Once again, we verified that we had the connectors properly connected to the mainboard. I disconnected all 1394 devices on my system and re-energized my system.
Using the pinout information located in the IEEE 1394-1995 specification, I found a MAJOR wiring problem on the top 1394 socket on both of our cases. The VG (Ground) and VP (Positive) pins are reversed. The mainboard VG wire (Ground) connects to pin 1 of the top 1394 socket, which SHOULD be connected to pin 2. The mainboard VP wire (+12v) connects to pin 2, which should be connected to pin 1. All other TP data pins are correct. As a final test, I plugged the cable back into the mainboard per the pinouts in the A7N8X motherboard manual, and used a multimeter to measure voltages on the pins. I measured 12V+ on pin 2 of the top firewire connector.
Some people might wonder why my wife’s Creative Nomad Jukebox III, which uses a 4-pin 1394 cable, was damaged by this problem. As you may know, 4-pin 1394 cables do not provide bus power to the connected device, however, If you actually use a multimeter to measure continuity between the 6-pin plug and the 4-pin plug of a 1394 cable, you’ll see that the outer metal shield of the 6-pin plug is NOT connected to the outer metal shield of the 4-pin plug. Instead, pin 2 of the 6-pin plug (GND) is actually connected to the 4-pin plug outer metal shield. That means that when you use this kind of cable with the Xaser III 1394 socket, you’re actually connecting POSITIVE 1394 bus power voltage to the shield of the 4-pin connector, not GROUND, which directly shorts out the controller chip. Cable shields are normally assumed to all be common, and if the Xaser III’s 1394 socket was properly wired, it would be. Imagine the potential damage you could do to your car if you installed your battery backwards and that should give you some idea of what’s happening in this situation. While fuses can protect electronic circuits from over-current situations, they don’t protect a circuit from reverse-polarity – that’s what diode’s are for. Unfortunately, most PC peripherals don’t incorporate circuit protection measures to guard against the possibility of reverse polarity, because they assume that the manufacturers who create these devices all follow the same specification and actually test their devices before delivering them to their customers. Thermaltake obviously didn’t test the Xaser III’s 1394 socket using a bus-powered device or they would have seen this problem.
hi, i am currently thinking seriously about buying the Xaser 3, i currently have the specs below; however, i am looking for advice on which power supply to purchase. Any help would be brill :-)
I am resident in the UK and i realise that voltages are different, but do not have the required expertise!!!
ps. is the Xaser 3 cool or naff?
Full KT 400 Mobo
AMD Athlon 2600+
Radeon 9500 Vid card
usb/firewire expansion card (pci)
3.5 front panel card reader
3.5 front floppy drive.
any help or advice would be cool.
<font color=blue>beware of Psychiatrists because they always have a silent'P'!!!</font color=blue><P ID="edit"><FONT SIZE=-1><EM>Edited by darth_aldo on 07/02/03 01:07 PM.</EM></FONT></P>
Sonartech, I would like to thank you for the work you have done on this situation.
You went the extra mile for everyone who buys these cases.
I am going to look at your site again in more detail, but I hope your URL is sent to ALL the other manufactures... in a sense, they are responsable for damages caused by these defects. User error is one thing (and I have ERRORED before like anyone else) but manufacture error on this is bad.
I have a two question for you... and I AM GLAD I came across your post. As we're about to order such a case.
1 - Is there an END-USER solution? I assume its like my Antec case in which the Firewire cables (to the board) are 5~6 individual connectors. Which case, the error is a labeling issue (cheap fix for the OEMer).
2 - Not the same issue, but what I've read about these cases and the reason I came to this section. The "tooless" Expansion Slot system has a SERIOUS design flaw in that it cannot handle LARGE Height cards (like my Ti4200 or most Fx5900 and ATI 9700 cards). From what little I've read, this "tooless" system can be removed and normal screws can be used to secure the cards. So with this, I assume that there are STANDARD Slot in the back of the case, no drilling or other modifications required?
The case my friend is ordering is the Enermax Enermax CS-10181 case. It is the exact same case as the ThermalTake, but without the Extreme cover or fan controls, costs about $65... a lot cheaper than $190! The other reason we like is, is that the TOP bay has a CD-ROM cover & eject button, so he doesn't have to OPEN the whole door to use the CD-ROM drive. That's one of the reasons we chose it over the Older Chieftech/Antec style cases.
When we get it, I will take a photo of its Datecode and other features you are requesting.
I have the Older Antec style of these cases (used by Alienware, Chieftec and others) - and view these NEW ones as refined models, with easier drive cages, tooless, more ports, etc. But has great reviews, and I've seen the ThermaltakeIII in real life... but it seems to have just these 2 BIG/small problems.