Re: When should a power supply be declared Perma-Dead?

[Don Bruder <dakidd@sonic.net>]

In article <1148884726.234457.38930@38g2000cwa.googlegroups.com>,
 "General_Failure" <tristan.mumford@gmail.com> wrote:


> And also, like I said, even with no connection to the //e, the fuse
> still instantly blows. There is no visible sign of damaged components
> in the power supply either.

That tells me for certain that it's a PS problem, not a MB or card 
problem, and further isolates it to the "high voltage" (110 volt) 
section of the supply. 

Without having the PS in my hands so I can prod it with a meter and 
such, I can't be sure, but my first bet would be that one or more of the 
main rectifier diodes has failed in "I'm now a wire, even though I look 
like a diode" mode. Such a failure *DOES NOT* always show up as a 
visibly damaged component.

Aside from something shifting to short the 110 lines, that's pretty much 
the only component failure that *CAN* cause what you're describing. 

If the problem were in the "low voltage" section, what you'd get when 
you switched on the PS would be either nothing at all, or a repeating 
"click-squeee" noise (It's possible that your ears can't hear it, though 
- Some people can hear the click, but not the "squeee", others can't 
hear either one, and still others hear both quite clearly) but not a 
blown fuse. Ditto if it were a MB/card problem.

-- 
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