> Date: Sun, 09 May 2004 21:03:13 +0200 > From: Roberto Giannotta <[EMAIL PROTECTED]>
> I'd have a problem: I've just discovered that the bottom three > PCI slots of my Power Mac 9500 don't work - or so it seems, at least. > > Looks like the circuit controlling the other three slots is faulty. Any > idea of what to check? Unless you're up for some delicate soldering or know someone who is, there probably isn't anything that you can do. Before going into the likely causes let me head off the folks who are going to ask you about your CPU upgrade. Only G4 upgrades have issues with six slot machines. As far as I know there are no issues with G3 upgrades. However, you're using a Sonnet upgrade and they have more compatibility issues than any other brand in my experience, so you may wish to try switching CPU cards as a test. The lower three slots are dependent on just two chips. Or rather, there are only two chips that can fail and affect the lower three slots without affecting the upper three slots and all the motherboard IO. These two chips are the Bandit chip (343S0020) with 208 pins and the PCI Bus Arbiter (for the lower bus) 343S0182 with 28 pins. You'll note that you have two of each of these chips, but the board is laid out pretty clearly so that you can see which goes with the upper three slots and which with the lower three slots. Either of those chips could be faulty, or you could simply have a poor or aging solder joint on one or more pins. You might also look for physical damage, e.g., bent pins that are shorting to each other. It is also possible that the connection to the clock buffer could be bad, but in order for that to be the problem, the one pin on the clock buffer that supplies the second Bandit would have to be bad and the other pins good (so the upper PCI slots would still work). The clock buffer is a little 16 pin chip (eight on each of two long sides) and I dont' remember the markings on it, but as I said it supplies clock signals to bother PCI busses so the probability is against it being the problem. If you find that you do have the skill to work on this at the board level and one of the chips is faulty, you cannot buy new replacements; they must be salvaged from old machines. However, 7200 boards are going on the trash heap these days and they have the required Bandit and Arbiter chips on them, so you can get replacements by making it worth someone's while to send you a 7200 board. I bought a PTP board off of Ebay with a similar problem a year or two ago, and just touching up the pins on the lower Arbiter chip fixed up the lower slots. Jeff Walther -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
