On Jul 10, 2010, at 11:24 PM, John Carmonne wrote:
Would the replacement of the port be the answer, is there an electronic issue from some controller on the board possible? The Cube boards aren't too costly but the PM G5 Dual 2.7 isn't that easy to find, so that's the one I want to repair.
If you need FW400 ports add a PCI card, they're cheap, probably $10 or less. I prefer ones with TI (Texas Instruments) chipsets, but many others work OK too. I can't see replacing a working motherboard just because FW400 ports don't work. The fact that your FW800 port is working means that the bridge chip is OK since only one chip controls both the FW400 & FW800.
I've seen cases where the System software was causing problems for FW400. Firewire normally shown early in the verbose startup dialog (look in System.log in Console), and when it's bad instead of saying "S400" for speed, it says "S100" instead. This means that it's somehow defaulted to an earlier version of 1394a that was only 100 Mbps instead of the 400 Mbps standard. When it defaults to this slower speed it normally won't mount any FW400 devices until this issue is fixed. I've only seen this happen on PCI Firewire cards, not built-in Apple Firewire, so I doubt this is your issue.
More likely someone plugged in a cable with the polarity reversed. This isn't supposed to be possible since one end is V-shaped and the other end isn't, but the tolerances are sloppy for Firewire, and it's very easy to force a cable the wrong way, and this will fry a Firewire port. I don't know what gets fried, perhaps there is a fuse or fusible resistor inline that could be replaced and you'd get it to work again? Disassembly of a G5 wouldn't be worth the time in my opinion as long as you have a free PCI port to add a cheap FW400 card to. You can get cards that have three, four, or even more ports. I'd forget about replacing the motherboard and get the PCI card.
-- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list
