Can ATX PSU blow the mainboard?

Can an overheating ATX PSU blow the mainboard if the PSU fails?

I may be mistaken but ISTR there's a possibility of a voltage surge when
the PSU goes.

On Wed, 30 Oct 2013 21:23:54 GMT, Jason wrote:

Can an overheating ATX PSU blow the mainboard if the PSU fails?

I may be mistaken but ISTR there's a possibility of a voltage surge when
the PSU goes.

A good one should not. But then even a good one that's been overheated
for too long may no longer be any good. And a bad one could do
anything.

So it's certainly possible. Get a new PSU and see if the machine comes
back up. If not, it's time to spend more money.

Cheers - Jaimie
--
The physics and scientific approach of Armageddon was criticized for its
poor adherence to the laws of physics. This has led NASA to show the
film as part of its management training program. Prospective managers
are asked to find as many inaccuracies in the movie as they can.

On Wed, 30 Oct 2013 21:23:54 GMT, Jason wrote:

Can an overheating ATX PSU blow the mainboard if the PSU fails?

I may be mistaken but ISTR there's a possibility of a voltage surge when
the PSU goes.

Apart from the well known infamous Bestec ATX psus used by eMachines
models harking back a decade ago, most ATX PSUs fail without damaging
the MoBo.

The usual failure mode when SMPSUs overheat is for the switching
transistors in the HT module to go short circuit and smash the safety
fuse to smithereens in a flash of light accompanied by a loud pop and
a trace of smoke.

When a PSU shuffles off its mortal coil with such drama, only a
single modest transient voltage spike appears on the voltage rails
(the very small ferrite transformer can only transfer a limited amount
of power due to such a _single_ terminal pulse of current) which is
incapable of causing damage. IOW, the kindest failure mode wrt the
load is that dramatic sudden fuse shattering failure of the switching
transistors in the HT module.

There are other types of failure involving sustained overvoltage but
these tend to be rare unless the manufacturer goes out of his way to
bypass/ignore the overload/overvoltage protection features built into
all the standard smpsu controller chips that made it possible to
manufacture ATX psus at all in large volumes at affordable prices.

If the ATX PSU in question went "BANG!", then it's most likely that
no harm has been done and a drop in replacement ATX PSU will get
things working again.
--
Regards, J B Good

In article , johnny-b-
says...

On Wed, 30 Oct 2013 21:23:54 GMT, Jason wrote:

Can an overheating ATX PSU blow the mainboard if the PSU fails?

.... (good stuff) trimmed.

If the ATX PSU in question went "BANG!", then it's most likely that
no harm has been done and a drop in replacement ATX PSU will get
things working again.

An acquaintance brought me a machine which had gone bang in this way
last year. I dropped in a cheap replacement PSU, and it seemed fine. I
left it running overnight. In the morning it was inert. Tested the PSU
- now dead. Tested a second PSU and dropped that in. Still inert.
Tested the second replacement PSU again - dead. This problem was
clearly out of my pay-grade, so sent it to a normally reliable repairer
I'd used before. They said they couldn't fix it - motherboard had gone
- and advised sending it back to the manufacturer (Carillon). They
replaced the motherboard, and also the hard disk, discarding the old
one, along with all my acquaintance's most precious data. Ex-
acquaintance now - he blamed me, and was very unpleasant. I guess I
could have backed up his data for him, but he hadn't, and wanted
everything on the cheap. People often won't pay for the time it takes
to do things properly, and then there's outrage when something goes
wrong (thankfully very rare so far).

Oddly, I've just told a valued customer (valued mainly because he's such
a nice bloke) that I'll do his repair for free now because it's taken so
long to find time to do it. And I realise I'm immediately taking more
precautions (e.g. imaging everything plus data snapshots) because it
won't cost him any more. I'm not cut out for this work...

--

Phil, London

Philip Herlihy wrote:
In article , johnny-b-
says...
On Wed, 30 Oct 2013 21:23:54 GMT, Jason wrote:

Can an overheating ATX PSU blow the mainboard if the PSU fails?

... (good stuff) trimmed.
If the ATX PSU in question went "BANG!", then it's most likely that
no harm has been done and a drop in replacement ATX PSU will get
things working again.

An acquaintance brought me a machine which had gone bang in this way
last year. I dropped in a cheap replacement PSU, and it seemed fine. I
left it running overnight. In the morning it was inert. Tested the PSU
- now dead. Tested a second PSU and dropped that in. Still inert.
Tested the second replacement PSU again - dead. This problem was
clearly out of my pay-grade, so sent it to a normally reliable repairer
I'd used before. They said they couldn't fix it - motherboard had gone
- and advised sending it back to the manufacturer (Carillon). They
replaced the motherboard, and also the hard disk, discarding the old
one, along with all my acquaintance's most precious data. Ex-
acquaintance now - he blamed me, and was very unpleasant. I guess I
could have backed up his data for him, but he hadn't, and wanted
everything on the cheap. People often won't pay for the time it takes
to do things properly, and then there's outrage when something goes
wrong (thankfully very rare so far).

Oddly, I've just told a valued customer (valued mainly because he's such
a nice bloke) that I'll do his repair for free now because it's taken so
long to find time to do it. And I realise I'm immediately taking more
precautions (e.g. imaging everything plus data snapshots) because it
won't cost him any more. I'm not cut out for this work...


If you plan to repair a lot of PCs, I recommend a couple things.

1) Everyone should have a multimeter, because you can
get a basic one for $20. And it allows checking
the voltages. So bang for buck, it's a good deal.

Measuring current flow, requires a breakout
cable of some sort - you need to be "in series"
when using one of those, to measure current flow.
Measuring all the rails would take all morning.

2) A second item, more expensive, is a DC clamp-on ammeter.
I can wrap the jaws of that, around wires of the same color
on the main ATX power cable, and make current measurements.
And see whether the load is normal or not. Or whether
the load is really too much for the replacement supply.
There are many AC clamp-on ammeters, but DC capable ones
are fewer in number. The DC ones use a Hall probe for
the measurement.

I got one like this, an Extech, before they got the ugly
color scheme. Mine is grey in color, throughout. For PC
work, the main range of value is the 40A DC range. The 400A
range is good for working on my car (detecting the starter
motor in the car drawing 150A peak current). The thing has
peak hold, so you can find the "worst" loading during
a session if you want. The Hall Probe has a tendency to
wander, so you have to zero it with the zero button on
the front.

http://www.drillspot.com/products/88...clamp_on_meter

It also has AC amps, and I use one of the AC ranges for
working on electric motors. Like the 10A on my 230V
central air conditioner compressor.

That particular meter, isn't sensitive enough to work with
small currents. But for the range a PC might draw,
you can do some service work with one. For example,
on my old AthlonXP system, when running Prime95, I
might see 16A on the +5V rail (because back then, the
processor used to run the switching converter off +5V.
Not all boards did that, but some brands preferred to
use +5V instead of +12V. This was before the ATX12V
cable became popular.

That one claims to have true RMS measurement capability
(probably up to around 50KHz or so), but when attempting
to measure the distorted waveform from a non-PFC power
supply, it does a poor job. I have to conclude it
really isn't True RMS. If you want to measure input power
to the PC with reasonable accuracy, a Kill-O-Watt meter
is good for that, and also, relatively cheap. That's one
tool I don't currently have in my collection - but if one
was sitting in the hardware store, I could not resist an
"impulse buy" if it was available.

Paul

On Thu, 31 Oct 2013 12:35:14 -0400, Paul wrote:

Philip Herlihy wrote:
In article , johnny-b-
says...
On Wed, 30 Oct 2013 21:23:54 GMT, Jason wrote:

Can an overheating ATX PSU blow the mainboard if the PSU fails?

... (good stuff) trimmed.
If the ATX PSU in question went "BANG!", then it's most likely that
no harm has been done and a drop in replacement ATX PSU will get
things working again.

An acquaintance brought me a machine which had gone bang in this way
last year. I dropped in a cheap replacement PSU, and it seemed fine. I
left it running overnight. In the morning it was inert. Tested the PSU
- now dead. Tested a second PSU and dropped that in. Still inert.
Tested the second replacement PSU again - dead. This problem was
clearly out of my pay-grade, so sent it to a normally reliable repairer
I'd used before. They said they couldn't fix it - motherboard had gone
- and advised sending it back to the manufacturer (Carillon). They
replaced the motherboard, and also the hard disk, discarding the old
one, along with all my acquaintance's most precious data. Ex-
acquaintance now - he blamed me, and was very unpleasant. I guess I
could have backed up his data for him, but he hadn't, and wanted
everything on the cheap. People often won't pay for the time it takes
to do things properly, and then there's outrage when something goes
wrong (thankfully very rare so far).

Oddly, I've just told a valued customer (valued mainly because he's such
a nice bloke) that I'll do his repair for free now because it's taken so
long to find time to do it. And I realise I'm immediately taking more
precautions (e.g. imaging everything plus data snapshots) because it
won't cost him any more. I'm not cut out for this work...


If you plan to repair a lot of PCs, I recommend a couple things.

1) Everyone should have a multimeter, because you can
get a basic one for $20. And it allows checking
the voltages. So bang for buck, it's a good deal.

+1 but it can't indicate high ripple and switching noise of course.


Measuring current flow, requires a breakout
cable of some sort - you need to be "in series"
when using one of those, to measure current flow.
Measuring all the rails would take all morning.

2) A second item, more expensive, is a DC clamp-on ammeter.
I can wrap the jaws of that, around wires of the same color
on the main ATX power cable, and make current measurements.
And see whether the load is normal or not. Or whether
the load is really too much for the replacement supply.
There are many AC clamp-on ammeters, but DC capable ones
are fewer in number. The DC ones use a Hall probe for
the measurement.

I got one like this, an Extech, before they got the ugly
color scheme. Mine is grey in color, throughout. For PC
work, the main range of value is the 40A DC range. The 400A
range is good for working on my car (detecting the starter
motor in the car drawing 150A peak current). The thing has
peak hold, so you can find the "worst" loading during
a session if you want. The Hall Probe has a tendency to
wander, so you have to zero it with the zero button on
the front.

I acquired a similar unit with 1200 and 200 A DC ranges. Despite the
high ranges, its saving grace for this sort of work was the fact that
it had a 4 digit display so could resolve to 0.1A.

The need for a zeroing button is an inherent feature of these DC
clamp meters. I just had a swift look at mine and it was showing
-127.4 A reading until I zeroed it. Even then I had to re-zero it
another 3 or 4 times before it stabilised.

This is something to watch out for when taking readings since you
have to double check the zeroing every few minutes to be sure your
reading is still valid if you need the accuracy to ascertain the total
DC power consumption to get a reasonably good idea of the PSU's
efficiency (when you've got a trustworthy AC watt meter to check the
mains input power).


http://www.drillspot.com/products/88...clamp_on_meter

It also has AC amps, and I use one of the AC ranges for
working on electric motors. Like the 10A on my 230V
central air conditioner compressor.

That particular meter, isn't sensitive enough to work with
small currents. But for the range a PC might draw,
you can do some service work with one. For example,
on my old AthlonXP system, when running Prime95, I
might see 16A on the +5V rail (because back then, the
processor used to run the switching converter off +5V.
Not all boards did that, but some brands preferred to
use +5V instead of +12V. This was before the ATX12V
cable became popular.

That one claims to have true RMS measurement capability
(probably up to around 50KHz or so), but when attempting
to measure the distorted waveform from a non-PFC power
supply, it does a poor job. I have to conclude it
really isn't True RMS. If you want to measure input power
to the PC with reasonable accuracy, a Kill-O-Watt meter
is good for that, and also, relatively cheap. That's one
tool I don't currently have in my collection - but if one
was sitting in the hardware store, I could not resist an
"impulse buy" if it was available.


Yep, the good ol' trustworthy Kill-A-Watt can be really useful to
check for unusually high (fault) loadings. I've got a couple of the
European versions and I'm quite impressed at their accuracy (compared
to some very early "Consumption Meters" I had the misfortune to buy
about 8 or 9 years ago). I have a MetraWatt analogue watt meter which
I bought a couple of decades ago which I use as the benchmark of
accuracy by which to assess these 'New Fangled' digital watt meters.

I'd certainly recommend you buy yourself an AC watt meter since this
can often provide all the information you need to assess what's going
on with a non-booting / no video display system. It's also handy to
avoid MoBo burnout when testing a box full of 2nd user CPUs for
shorted chips. :-)

--
Regards, J B Good

On 01:55 31 Oct 2013, Johny B Good wrote:

On Wed, 30 Oct 2013 21:23:54 GMT, Jason wrote:

Can an overheating ATX PSU blow the mainboard if the PSU fails?

I may be mistaken but ISTR there's a possibility of a voltage surge
when the PSU goes.

Apart from the well known infamous Bestec ATX psus used by eMachines
models harking back a decade ago, most ATX PSUs fail without damaging
the MoBo.

The usual failure mode when SMPSUs overheat is for the switching
transistors in the HT module to go short circuit and smash the safety
fuse to smithereens in a flash of light accompanied by a loud pop and
a trace of smoke.

When a PSU shuffles off its mortal coil with such drama, only a
single modest transient voltage spike appears on the voltage rails
(the very small ferrite transformer can only transfer a limited amount
of power due to such a _single_ terminal pulse of current) which is
incapable of causing damage. IOW, the kindest failure mode wrt the
load is that dramatic sudden fuse shattering failure of the switching
transistors in the HT module.

There are other types of failure involving sustained overvoltage but
these tend to be rare unless the manufacturer goes out of his way to
bypass/ignore the overload/overvoltage protection features built into
all the standard smpsu controller chips that made it possible to
manufacture ATX psus at all in large volumes at affordable prices.

If the ATX PSU in question went "BANG!", then it's most likely that
no harm has been done and a drop in replacement ATX PSU will get
things working again.

I'm the OP for this thread. The fan on my ATX PSU seems to slow down at
times and makes a noise so I guess it's approaching the end of its life.
My PSU has not overheated yet and I'm still using the PC until I manage
to change the PSU or maybe just the fan.

Can you help me with this? ... If my PSU does overheat and might fry the
mainboard then would a surge protector on the incoming mains prevent the
PSU suddenly drawing mains power to feed the surge?

(I'm in the UK where I understand the mains voltage tends to be
reasonably stable.)

En el artículo , Jason
escribió:

I'm the OP for this thread. The fan on my ATX PSU seems to slow down at
times and makes a noise so I guess it's approaching the end of its life.
My PSU has not overheated yet

How do you know?

and I'm still using the PC until I manage
to change the PSU or maybe just the fan.

It'll be too late by then. The PSU will have heated to the point that
the caps inside are damaged and no longer adequately smooth the output
voltages. When that happens, the motherboard caps, placed under
abnormal stress also begin to fail.

The time to change out your PSU is now, before motherboard damage
occurs.

would a surge protector on the incoming mains prevent the
PSU suddenly drawing mains power to feed the surge?

No, not at all. It deals with a surge on the *input*, not on the
output.

(I'm in the UK where I understand the mains voltage tends to be
reasonably stable.)

For now, but the Grid is approaching a point where backup capacity to
deal with unexpected outages (like Dungeness nuke station tripping
offline during last week's storms) is becoming marginal because so many
power stations, mainly coal burners, have been forced to close to comply
with Euro environmental ********.

This winter, expect brownouts at best and blackouts at worst. If no
more generating capacity is brought online next year and we can't import
enough power from the cloggies and frenchies over the interconnects,
blackouts *will* occur next winter.

--
(\_/)
(='.'=)
(")_(")

On Fri, 01 Nov 2013 16:32:27 GMT, Jason wrote:

On 01:55 31 Oct 2013, Johny B Good wrote:

On Wed, 30 Oct 2013 21:23:54 GMT, Jason wrote:

Can an overheating ATX PSU blow the mainboard if the PSU fails?

I may be mistaken but ISTR there's a possibility of a voltage surge
when the PSU goes.

Apart from the well known infamous Bestec ATX psus used by eMachines
models harking back a decade ago, most ATX PSUs fail without damaging
the MoBo.

The usual failure mode when SMPSUs overheat is for the switching
transistors in the HT module to go short circuit and smash the safety
fuse to smithereens in a flash of light accompanied by a loud pop and
a trace of smoke.

When a PSU shuffles off its mortal coil with such drama, only a
single modest transient voltage spike appears on the voltage rails
(the very small ferrite transformer can only transfer a limited amount
of power due to such a _single_ terminal pulse of current) which is
incapable of causing damage. IOW, the kindest failure mode wrt the
load is that dramatic sudden fuse shattering failure of the switching
transistors in the HT module.

There are other types of failure involving sustained overvoltage but
these tend to be rare unless the manufacturer goes out of his way to
bypass/ignore the overload/overvoltage protection features built into
all the standard smpsu controller chips that made it possible to
manufacture ATX psus at all in large volumes at affordable prices.

If the ATX PSU in question went "BANG!", then it's most likely that
no harm has been done and a drop in replacement ATX PSU will get
things working again.

I'm the OP for this thread. The fan on my ATX PSU seems to slow down at
times and makes a noise so I guess it's approaching the end of its life.
My PSU has not overheated yet and I'm still using the PC until I manage
to change the PSU or maybe just the fan.

The fan is simply showing a lack of lubrication, try cleaning all the
dust and fluff (vacuum and a 1/2 inch paintbrush makes an effect
combination) before putting a drop or two of oil into the fan spindle
bearing (rubber plug hidden beneath the manufaturer's sticker).

This should, at the very least, extend the life of the PSU (assuming
the fan responds favourably - as they typically do - to such
treatment). You can check the PCB for any obviously 'blown' caps
whilst you've got the cover off although, ime, replacing any such caps
is far from guaranteed to extend the life of the PSU (a far cry from
the effect of replacing such caps on a MoBo where it usually extends
the service life by a year or three)


Can you help me with this? ... If my PSU does overheat and might fry the
mainboard then would a surge protector on the incoming mains prevent the
PSU suddenly drawing mains power to feed the surge?

If the fan stops completely, the most likely failure will be the HT
switching transistors going short (a flash and a bang) which is
generally not likely to trouble any of its rails with a voltage spike
worthy of such a description (more likely a voltage blip).

As for the use of a surge protector this won't make any difference as
far as your theory of failure mode is concerned. However, it can
reduce the risk of a voltage spike triggering an 'avalanche' failure
due to excess temperature reducing the collector/drain breakdown
voltage of the HT switching devices. Do you have a particularly bad
mains supply with regard to spike voltages?


(I'm in the UK where I understand the mains voltage tends to be
reasonably stable.)

You've got that right! Here in the UK you just don't get the same UPS
ROI benefit as they do in most parts of the US of A. :-)

--
Regards, J B Good

On 22:32 1 Nov 2013, Johny B Good wrote:

On Fri, 01 Nov 2013 16:32:27 GMT, Jason wrote:

On 01:55 31 Oct 2013, Johny B Good wrote:

On Wed, 30 Oct 2013 21:23:54 GMT, Jason wrote:

Can an overheating ATX PSU blow the mainboard if the PSU fails?

I may be mistaken but ISTR there's a possibility of a voltage surge
when the PSU goes.

Apart from the well known infamous Bestec ATX psus used by eMachines
models harking back a decade ago, most ATX PSUs fail without
damaging the MoBo.

The usual failure mode when SMPSUs overheat is for the switching
transistors in the HT module to go short circuit and smash the
safety fuse to smithereens in a flash of light accompanied by a loud
pop and a trace of smoke.

When a PSU shuffles off its mortal coil with such drama, only a
single modest transient voltage spike appears on the voltage rails
(the very small ferrite transformer can only transfer a limited
amount of power due to such a _single_ terminal pulse of current)
which is incapable of causing damage. IOW, the kindest failure mode
wrt the load is that dramatic sudden fuse shattering failure of the
switching transistors in the HT module.

There are other types of failure involving sustained overvoltage
but
these tend to be rare unless the manufacturer goes out of his way to
bypass/ignore the overload/overvoltage protection features built
into all the standard smpsu controller chips that made it possible
to manufacture ATX psus at all in large volumes at affordable
prices.

If the ATX PSU in question went "BANG!", then it's most likely that
no harm has been done and a drop in replacement ATX PSU will get
things working again.

I'm the OP for this thread. The fan on my ATX PSU seems to slow down
at times and makes a noise so I guess it's approaching the end of its
life.

My PSU has not overheated yet and I'm still using the PC until I
manage to change the PSU or maybe just the fan.

The fan is simply showing a lack of lubrication, try cleaning all the
dust and fluff (vacuum and a 1/2 inch paintbrush makes an effect
combination) before putting a drop or two of oil into the fan spindle
bearing (rubber plug hidden beneath the manufaturer's sticker).

This should, at the very least, extend the life of the PSU (assuming
the fan responds favourably - as they typically do - to such
treatment). You can check the PCB for any obviously 'blown' caps
whilst you've got the cover off although, ime, replacing any such caps
is far from guaranteed to extend the life of the PSU (a far cry from
the effect of replacing such caps on a MoBo where it usually extends
the service life by a year or three)


Can you help me with this? ... If my PSU does overheat and might fry
the mainboard then would a surge protector on the incoming mains
prevent the PSU suddenly drawing mains power to feed the surge?

If the fan stops completely, the most likely failure will be the HT
switching transistors going short (a flash and a bang) which is
generally not likely to trouble any of its rails with a voltage spike
worthy of such a description (more likely a voltage blip).

As for the use of a surge protector this won't make any difference as
far as your theory of failure mode is concerned. However, it can
reduce the risk of a voltage spike triggering an 'avalanche' failure
due to excess temperature reducing the collector/drain breakdown
voltage of the HT switching devices. Do you have a particularly bad
mains supply with regard to spike voltages?


(I'm in the UK where I understand the mains voltage tends to be
reasonably stable.)

You've got that right! Here in the UK you just don't get the same UPS
ROI benefit as they do in most parts of the US of A. :-)

Thanks for the info. I've cleaned the dust off (it was pretty clean
anway as I keep an eye on dust) and it didn't make any difference.

I hadn't realised I could lube the fan so I'll try that. While the PSU
is open I'll note the fan's fittings and get a spare one in case it's
too far gone for the lube to help.

Maybe I should also get a spare fuse. If the fuse markings are
indistinct, what's the typical fuse value for a 250W ATX PSU? (The
actual PSU model is FSP250-60GTV.)