philo said:
About 10 years ago I built my wife a top of the line XP_64 machine which
included an Antec 500 watt PSU
After I built her a new machine a few years ago, I kept the old one in
my office just for use as a backup machine. Woke up yesterday morning to
a slight burned smell. That good 500 W psu apparently died in it's
sleep. (Unit was plugged into a UPS, so not likely to have been a surge.)
Replaced it and when I turned the machine on the video was scrambled
even before it started to load the OS...so replaced the video card and
tried again.
Dang..that PSU also took out the DVD and hard drive!
One of the worst disasters I've seen. The machine is now running Win7,
so XP_64 is a goner. (The Win7 drive was fortunately not hooked up at
the time of failure.)
Good spare machine.
Antec doesn't make their own power supplies.
They contract others to do it.
I've lost two Antecs made by Channelwell. If
you look inside the power supply (lid off, don't
touch), you may see "CWT" printed on a transformer
or two. Stands for "ChannelWell Technologies".
They do use other suppliers. Perhaps Delta was used
for the Earthwatts ?
I think Channelwell can make good product when you
pay them. If you insist on a low build price, they
put the nastiest caps in there they can.
Now, as to your symptoms, those are disturbing, because
it means the supply had no OVP (overvoltage protection).
The easiest way to do what happened to you, is have
the feedback path on the supply cry out "more coal, more coal",
causing the switching circuit to "go to the wall" in
terms of driving the primary side. All rails rise
on the output side. A well designed supply senses the
out-of-spec output condition, and removes drive
from the switching transistors. That should be a
separate control path, a "monitor" that has a
"kill switch" it can use.
It pays to check the specs, to see if OCP, OVP, and
the like, are listed in the specs. The last time
we heard of a lot of failures of that type, it
was a Bestec branded design doing it (with no
OVP at all).
*******
In the case of the ATX supply, there are two switching
transistors on the primary side of the isolation
transformer, that make an AC waveform. Power can't
pass from the primary to the secondary, unless the
waveform remains AC (alternating current). So to
implement an OVP/OCP, all you need to do is stop
the switching circuit from making AC. Even if a
primary side transistor fails ON, if the second
transistor is not alternating, then no power ends
up on the other side. It means though, that the
control path has to be opto-isolated, as
anything passing from (isolated) secondary
to primary side, has to honor the isolation.
The supply can be tested with up to 1100 volts (HiPOT),
to make sure the secondary is well-isolated
from the primary.
Next time, *explicitly* check the supply specifications
for overcurrent and overvoltage protection. Now that
you know what an Antec is really worth.
*******
Now that hard drive PCBs are inverted, you'll have
no chance to check for burned components on it.
There are two transient suppressors near the
power inlet terminals. They're there to stop
15v inductive ringback from damaging stuff
(on the 12V motor rail). When a sustained overvoltage
condition exists, the protection device on the 12V and
5V rails, should get burned. If you've given up on
the hard drive, you can flip the PCB over and take
a look.
If you could find a matching PCB, it's possible a
new PCB would make the drive work. But what are the
odds of finding the exact right PCB ? The heads
might be far enough from the event, to have survived,
so all your data is still there.
Paul
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