On May 21, 2010, at 3:23 AM, Mac User #330250 wrote:
I have a problem with my G5 “Late 2005” 2.0 GHz Dual-Core Power Mac.
About two
months ago, as I was switching it on, I heard a loud BANG and only
silence
ever after. It plays dead ever since, I don't even hear the click when
plugging it in.
I figured the PSU must have died, most likely due to a blown
condensator. But
I'm not 100% sure.
Since a new PSU is >150 $ (710 W as well as 1000 W) and most of them
are in
used condition, I figured I might as well try to fix the broken one
I have at
hand.
It took me a while to figure out how to get the PSU out of the case,
and now
that I finally got to it, I find that there is no visible defect
inside the
PSU.
*So my questions are:*
If a condensator actually did blow up, shouldn't it be a visible
defect?
In english the term is "capacitor" for "kondensator" and normally
they're "popped" and clearly visible:
<http://www.mad-monkey.co.uk/resources/pchf/capacitor.jpg>
In the photo the "popped" ones have the red arrows and the tops are
"popped" upward, the 3 on left are still good with flat tops.
If not so, how am I gonna find out where the fault is?
Or even worse, if the loud BANG didn't come from the PSU, but from
the system
board or… <I don't know what>, how can I test if the PSU is in working
condition without it being connected to the Power-On button?
Bummer. I'd strongly believe the loud BANG means your power supply is
DEAD (for good). Mine didn't make such a loud noise when it died for
good, but I could smell it, and I could measure that the voltages from
all the 5v & 3.3v lines were gone. You can probably measure them using
this pinout:
<http://img212.imageshack.us/img212/8477/g5psupinoutp1cn8.png>
Most likely you're about 6 months too late for a free replacement from
Apple:
<http://www.apple.com/support/powermac/powersupply/repairextension/>
<http://web.archive.org/web/20080722225628/http://www.apple.com/support/powermac/powersupply/repairextension/
>
You may be able to use a much cheaper standard ATX power supply as a
replacement:
<http://damntechnology.blogspot.com/2009/02/rebuilding-powermac-g5-power-supply.html
>
When Apple replaced my power supply under the extended warranty
program they also replaced the logicboard and both CPUs. They told me
this wasn't always necessary and the old ones were sent away to be
checked out and re-certified if possible for use in future repairs,
but they do each repair locally and it's cheaper to swap out the
logicboard & CPUs with "known good" ones rather than test the old ones
for possible damage "on the spot". I'm saying this because it's
possible the blown power supply ruined your logicboard or a CPU, and
your repair will be wasted time and effort.
I'd recommend looking for a cheap used Apple power supply (hard to
find for cheap), or try the ATX conversion with a suitable wattage
higher quality ATX unit, perhaps used also (game players are always
selling old power supplies as they buy video cards that eat more &
more power). It's a risk, but I'd probably try it myself. Good luck!
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