Blown power Supply

  • Thread starter Thread starter tony h
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tony h

hope someone can save me hours of grief.
my son cleverly decided to flick the voltage switch on the back of the power
supply, changing from 220v (uk where we live) to 110v, as the supply was on
at the time this was followed by a 'green flash'. obviously the computer
doesn't work anymore.
before i start stripping my pc down to check components (starting with
changing the psu) is the general opinion that the whole pc will be buggered,
motherboard, cpu, ram, gpu, drives etc.. or may i be lucky?
i'm guessing that a surge of double the required voltage may have been
issued throughout the whole pc, but am hoping that there maybe a fuse or
something in the power supply that saved everything else.
thanks for any help /advice
 
tony h said:
hope someone can save me hours of grief.
my son cleverly decided to flick the voltage switch on the back of the
power supply, changing from 220v (uk where we live) to 110v, as the supply
was on at the time this was followed by a 'green flash'. obviously the
computer doesn't work anymore.
before i start stripping my pc down to check components (starting with
changing the psu) is the general opinion that the whole pc will be
buggered, motherboard, cpu, ram, gpu, drives etc.. or may i be lucky?
i'm guessing that a surge of double the required voltage may have been
issued throughout the whole pc, but am hoping that there maybe a fuse or
something in the power supply that saved everything else.
thanks for any help /advice
Click to expand...
Simple answer is to try another PSU.
You could be Lucky.
 
DaveW said:
There are no fuses in PSU's.
Click to expand...

Every PC PSU I've seen had at least one fuse in the high voltage
section, and those Antecs made by Channel Well Technology (SmartPower,
TruePower) have two. But if a fuse blows, the high voltage
transistor(s) almost always get destroyed as well.
 
DaveW said:
There are no fuses in PSU's.
Click to expand...

???

There are plenty of fuses. There is *at minimum* a fuse in the
incoming AC line. Some supplies have fuses in their soft start
circuitry and switching circuitry as well. Some even have fuses
in their output circuitry. No fuses in PSUs? Indeed...
 
tony said:
hope someone can save me hours of grief.
my son cleverly decided to flick the voltage switch on the back of the power
supply, changing from 220v (uk where we live) to 110v, as the supply was on
at the time this was followed by a 'green flash'. obviously the computer
doesn't work anymore.
before i start stripping my pc down to check components (starting with
changing the psu) is the general opinion that the whole pc will be buggered,
motherboard, cpu, ram, gpu, drives etc.. or may i be lucky?
i'm guessing that a surge of double the required voltage may have been
issued throughout the whole pc, but am hoping that there maybe a fuse or
something in the power supply that saved everything else.
thanks for any help /advice
Click to expand...

A decent PSU would have blown its input fuse, lost some 300v buss
circuitry, but saved the MB and rest of the computer. Since yours
didn't, anything is possible.
 
hope someone can save me hours of grief.
my son cleverly decided to flick the voltage switch on the back of the power
supply, changing from 220v (uk where we live) to 110v, ...
before i start stripping my pc down to check components (starting with
changing the psu) is the general opinion that the whole pc will be buggered,
motherboard, cpu, ram, gpu, drives etc.. or may i be lucky?
Click to expand...

If if damaged anything but the powr supply, then never use that
computer retailer again. No other electronics can be damaged by any
power supply failure. A standard even 30 years ago and demanded even
in Intel specs.

Fuses are to protect you after damage has occurred. Fuses typically
do not protect electronics. Very little would be damaged inside the
supply, but, it is easier to replace a supply.

BTW, you may consider what is called a universal supply - that
automatically does that switching inside. For example, all cell
phones, camcorders, laptops, etc must use a universal supply. How do
you know? The lable says 90 to 265 volts AC. Must work on any
voltage in that range. No switch and no worry.
 
hope someone can save me hours of grief.
my son cleverly decided to flick the voltage switch on the back of the power
supply, changing from 220v (uk where we live) to 110v, as the supply was on
at the time this was followed by a 'green flash'. obviously the computer
doesn't work anymore.
Click to expand...

If you feel this could happen again with another PSU, either
put a blob of epoxy over the switch, modify the switch
circuit by removing it (it is easy, but someone who can do
it safely, likely needs not to be told how), or buy an
active PFC type PSU which has no switch.

before i start stripping my pc down to check components (starting with
changing the psu) is the general opinion that the whole pc will be buggered,
motherboard, cpu, ram, gpu, drives etc.. or may i be lucky?
Click to expand...

In general only the PSU should be damaged, it would be
unlucky if anything else were, the PSU should have shut down
immediately if any outputs were over spec but with the
problem what it was, you probably have fried transistors
which are not hard to replace but beyond what a typical user
can do themselves, and generally not cost effective to have
repaired by a shop unless it was a very expensive/exotic
PSU.

i'm guessing that a surge of double the required voltage may have been
issued throughout the whole pc, but am hoping that there maybe a fuse or
something in the power supply that saved everything else.
thanks for any help /advice
Click to expand...

Not exactly, no matter what the incoming AC, the PSU
regulates by PWM to arrive at an output voltage.
Unfortunately there is only a certain range in which it is
stable, and only a certain range under which the (cost
effective) parts can function before being overvoltage or
overcurrent (parts in the PSU, not in rest of system).
Within tiny fractions of a second the PSU would have
corrected for the problem and be outputting roughly correct
voltages still (even if a bit noisey, probably the system
would keep running w/o fault) , except that a part earlier
in the power path was not spec'd to handle (not within
running parameters but max/failure) this running state. A
decent PSU would make it unlikely to damage anything else,
but a poor one is anyone's guess.

There is no foreseen need to change anything but the PSU
right now. In the less likely event something else has
damage, it would be indicated at that point of being able to
test with the replacement PSU.
 
Every PC PSU I've seen had at least one fuse in the high voltage
section, and those Antecs made by Channel Well Technology (SmartPower,
TruePower) have two. But if a fuse blows, the high voltage
transistor(s) almost always get destroyed as well.
Click to expand...

One has to wonder if DaveW has ever seen the inside of a
PSU, the fuse is pretty hard to miss on most of them.

I tend to agree that if the fuse is blown the transistors
are shot, but not necessarily the other way around,
transistors can blow without taking out the fuse.
 
update

replaced the power supply, that removed the burning smell!
booted the PC, reported 512mb instead of 768, so i thought 256mb had died.
turns out my (non technical) son had removed 1 stick to try another, and had
not replaced it properly (only held in on one side).
turned into a fun time all round, fixed the ram, booted into xp, then AVG
started shouting at me that pc had infections, and A/V software out of date!
started download of avg 7.5 and pc hung. after 2 or 3 mins taskmanager
loaded to sho svchost.exe using 100% cpu. ended the process and lost
wireless, restarted wireless service and reconnected to complete download,
and now added antispyware from grisoft (got adaware and spybot sd, but the
svchost got me worried).
all downloads finished and installed, rebooted into safe mode and cleared
all the crap (again). hopefully he will learn to listen to the alerts that
pop up warning him, and that 'free' internet porn has a price...my sanity!

thanks for the advice.
....until next time (last major spyware infection.....last week on 4 pcs (all
in the house but mine)!
 
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