Clark Martin Worte: >>Power supplies have protection circuitry to limit stray electrical surges >>from causing haboc to the motherboard and peripherals. Its MOSFET absorbs >the "shock" and blows up before it hurts the rest. > >It's MOVs (Metal Oxide Varisistor IIRC) not MOSFETs that absorb >surges. MOSFETs are the likely switching device. A little known >fact about MOVs is that they wear out with usage. The more surges >and the more powerful the surge, the sooner it wears out. When they >were "gently" they typically fail open, thus no longer providing any >protection. When they wear out with a large surge they tend to short >out. And you would be surprised just how much smoke a little sucker >like that can make (especially when you hit it with 220 VAC @ >something in excess of 70A. > >I can't say if it was a problem in this case but it can happen.
Dead 8500/8600/9500 power supplies I have examined didn't seem to have MOVs anywhere in their circuit. But all their MOSFETs were not working, among other components - merely replacing them doesn't restore function. Our local power here is 220-240V 60 Hertz so some surge protected powerstrips we get from the west coast blows up unless their MOVs are replaced with 270V types. Charlie -- 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
