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Can ATX PSU blow the mainboard?



 
 
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  #21  
Old November 3rd 13, 09:27 PM posted to alt.comp.hardware.pc-homebuilt,uk.comp.homebuilt
GS[_4_]
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Default Can ATX PSU blow the mainboard?

Jason wrote:

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.


If it's just the fan, you can replace that, Maplins sell case fans for
about a fiver IIRC, you just need to get the right size. I replaced mine
after it started making a continual buzzing sound. The only touble was the
original had been hardwired rather than connected with a plug but I was
able to connect the new one up without much difficulty anyway.

  #22  
Old November 3rd 13, 09:56 PM posted to alt.comp.hardware.pc-homebuilt,uk.comp.homebuilt
Jason[_14_]
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Default Can ATX PSU blow the mainboard?

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.)

  #23  
Old November 4th 13, 12:31 AM posted to alt.comp.hardware.pc-homebuilt,uk.comp.homebuilt
Johny B Good
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Default Can ATX PSU blow the mainboard?

On Sun, 03 Nov 2013 20:56:28 GMT, Jason wrote:

====snip====


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.)


I wouldn't worry about replacing the fuse. It's soldered in because
the most likely reason for _its_ failure would be a component failure
in the HT module (rectifier, HT smoothing capacitor(s) or switching
transistor(s)) which would require the use of a soldering iron anyway
in the event of any attempts at repairing the fault.

The safety fuse (for that is what it is) is fitted simply to prevent
catastrophic HT component failure becoming a fire hazard. It's not
there to protect components in the HT module.
--
Regards, J B Good
  #24  
Old November 6th 13, 08:08 PM posted to alt.comp.hardware.pc-homebuilt,uk.comp.homebuilt
Jason[_14_]
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Default Can ATX PSU blow the mainboard?

On 23:31 3 Nov 2013, Johny B Good wrote:

On Sun, 03 Nov 2013 20:56:28 GMT, Jason wrote:

====snip====


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.)


I wouldn't worry about replacing the fuse. It's soldered in because
the most likely reason for _its_ failure would be a component failure
in the HT module (rectifier, HT smoothing capacitor(s) or switching
transistor(s)) which would require the use of a soldering iron anyway
in the event of any attempts at repairing the fault.

The safety fuse (for that is what it is) is fitted simply to prevent
catastrophic HT component failure becoming a fire hazard. It's not
there to protect components in the HT module.


Hello Johny. You were right about the fan needing a bit of lube.

This PC was manufactured in 2001 and has been used almost every day since
then for several hours, so I thought the fan bearings must be worn by now.
However your lube idea works. So far.

It must a better quality fan than I realised. It's an 80mm fan by Yate
Loon (model D80SH-12). Is that a good fan?
  #25  
Old November 6th 13, 11:22 PM posted to alt.comp.hardware.pc-homebuilt,uk.comp.homebuilt
Johny B Good
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Posts: 12
Default Can ATX PSU blow the mainboard?

On Wed, 06 Nov 2013 19:08:34 GMT, Jason wrote:

On 23:31 3 Nov 2013, Johny B Good wrote:

On Sun, 03 Nov 2013 20:56:28 GMT, Jason wrote:

====snip====


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.)


I wouldn't worry about replacing the fuse. It's soldered in because
the most likely reason for _its_ failure would be a component failure
in the HT module (rectifier, HT smoothing capacitor(s) or switching
transistor(s)) which would require the use of a soldering iron anyway
in the event of any attempts at repairing the fault.

The safety fuse (for that is what it is) is fitted simply to prevent
catastrophic HT component failure becoming a fire hazard. It's not
there to protect components in the HT module.


Hello Johny. You were right about the fan needing a bit of lube.


The bearings are often sintered bronze which, if properly lubed, can
outlast the more complex ball race bearings. Sometimes the
manufacturer fails to impregnate the porous sintered bearings with
enough oil causing them to prematurely gum up and chatter. If caught
in time, that extra drop of oil can make all the difference and extend
the life considerably.


This PC was manufactured in 2001 and has been used almost every day since
then for several hours, so I thought the fan bearings must be worn by now.
However your lube idea works. So far.


That's the big question mark, just how long is "so far"? It could
last for anywhere from a few months to several years depending on how
long it had been allowed to run 'dry' before the problem was fixed.

However, I'd say that PSU has lasted well to still be functioning
after some 12 years of daily use. My guess on the hours per day would
be something like just 2 or 3.

I've noticed that most ATX PSUs include a MTBF figure in their specs,
ranging from a poxy 10,000 hours for a cheap commodity unit right up
to 100,000 hours for the more pricey quality brands. 10,000 hours
represents around 3 1/2 years at 8 hours per day on a 6 day week which
is why I suspect the 2 or 3 hours a day usage in your case. The MTBF
is usually based on the quality of the capacitors used rather than on
the endurance of the fan.


It must a better quality fan than I realised. It's an 80mm fan by Yate
Loon (model D80SH-12). Is that a good fan?


I'm afraid I cannot say one way or the other. You could always try a
google search to get a better idea (and ditto for the PSU make and
model - although at 12 years old it's most likely to be only of
historical interest by now but you might find some anecdotal evidence
as to its quality).

Since you're, quite rightly, concerned about the reliability of that
PSU, I suggest you buy a suitably rated ATX PSU (either a cheap
commodity unit to keep as a spare or else invest in a better quality
one as a replacement - keeping the not yet failed original as a spare
for 'just in case'. I think it's reasonable to assume that your
existing unit is 'On Borrowed Time'.
--
Regards, J B Good
  #26  
Old November 9th 13, 12:20 AM posted to alt.comp.hardware.pc-homebuilt
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Default Can ATX PSU blow the mainboard?

On Wednesday, October 30, 2013 5:23:54 PM UTC-4, Jason wrote:
I may be mistaken but ISTR there's a possibility of a voltage surge when
the PSU goes.


If the PSU meets ATX specs and power supply standards long before the IBM PC existed, then no PSU failure damages any computer parts.

However, a power supply manufacturer is not required to meet ATX and other standards. The computer assembler is required to meet those standards. So some PSU manufacturers 'forget' to include many functions required to meet ATX and other standards.

They know many 'assume' it must be good because it boots the computer. Nonsense. The PSU can be defective or can be missing essential ATX functions. And will still boot a computer. But when a PSU part fails, many required functions inside every ATX compatible supply makes computer part damage all but impossible.

Damage from a particular supply indicates a supply marketed to computer assemblers without even basic electrical knowledge.

Heat is not the typical reason for PSU failure. All computer parts should be perfectly happy even in a 100 degree F room. Manufacturing defects are the most common reason for PSU failures. We all saw defectively manufactured electrolytic capacitors fail years later due to counterfeit electrolyte. Another example of reasons for most PSU failures.

  #28  
Old November 10th 13, 03:31 AM posted to alt.comp.hardware.pc-homebuilt
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Default Can ATX PSU blow the mainboard?

On Friday, November 8, 2013 9:07:05 PM UTC-5, Flasherly wrote:
Nonsense. Run a MB with failing capacitors. Besides a diet of PS
units, it'll also eventually take out drives.


Bad capacitors do not cause destructive voltages. If you knew otherwise, then you posted specifications and numbers to say so. You don't for one good reason. That damage is not possible. And spec numbers contradict those denials.

ATX specifications define protection ... with numbers ... that say why a PSU (properly designed) will not harm drives. If you know otherwise, then define the disk drive part put at risk. And provide numbers from datasheets that define why that part is damaged. Good luck.

PSUs contains circuits to prevent electronics damage long before the IBM PC even existed. Long an industry standard.
  #29  
Old November 10th 13, 05:17 AM posted to alt.comp.hardware.pc-homebuilt
Flasherly[_2_]
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Default Can ATX PSU blow the mainboard?

On Sat, 9 Nov 2013 18:31:53 -0800 (PST), wrote:

Bad capacitors do not cause destructive voltages. If you knew
otherwise, then you posted specifications and numbers to say so. You
don't for one good reason. That damage is not possible. And spec
numbers contradict those denials.

ATX specifications define protection ... with numbers ... that say
why a PSU (properly designed) will not harm drives. If you know
otherwise, then define the disk drive part put at risk. And provide
numbers from datasheets that define why that part is damaged. Good
luck.

PSUs contains circuits to prevent electronics damage long before the
IBM PC even existed. Long an industry standard.

--
That's certainly within reason, as well supportive of definable
standards within electrical laws governing them. However, you've went
too far to impinge localized damage is neither within reason or
demonstrably evident. What you need to do is get off my butt with
your numbers and publications, long enough to where I can supply good
reason for specifically why I'm citing a MB as catastrophic source for
PS unit failure(s);- yes, I went thru several -- one being among the
best made, which it literally smoked -- before ditching that
particular MB.

Expensive as in and for oh-wells.

OK. To be fair to you, I don't know and shouldn't have claimed with
certitude -- only -- that capacitors on the MB are the culprits. When
the MB in question did, however, eat PS units on a regular basis.

.... Probably went through three or four PS units over its course of
usage - a long one, with the problem surfacing, I'd estimate, at a
halfway point of its life. Aberant hard & software behavior had also
surfaced, also in conjunction, when a supplementary diet of power
supplies were provided, on average for a yearly basis, within some
subsequent, general improvement of a condition loosely classifable
for "coaxing it along."

As mentioned, I put in an industrial, server-grade PS on my last-ditch
attempt to revive the MB, whereupon it literally smoked it.

OK. So it wasn't capacitors, which just fine if you say so.

.... As I can't say, conversely, I'm well enough versed, otherwise, in
testing micro-electronics. I'd be, more correctly to back up and
revise my statement, "grasping" at a known period when several MBs
manufacturers equipped their products with bad capacitors - within the
same timeframe incident to when I purchased that particular ASUS MB.
As for the general hypothesis, then, I advanced: PSupply units are
impervious, tell me again you believe it. A good joke is never out of
place.
  #30  
Old November 10th 13, 05:53 PM posted to alt.comp.hardware.pc-homebuilt
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Default Can ATX PSU blow the mainboard?

On Saturday, November 9, 2013 11:17:18 PM UTC-5, Flasherly wrote:
OK. So it wasn't capacitors, which just fine if you say so.


If capacitors cause damage, then included is how capacitors cause damage to other electronics. In generations of design and support, I have never seen such damage. However, if you know how a capacitor can cause that damage, then please explain it.

Many see an incandescent bulb flash and burn out with power on. That proves power cycling damages light bulbs? Not for one minute. Conclusions based only in observation are classic junk science. To have a fact means also learning underlying principles and numbers. What damages light bulbs? Facts are well published even with industry standard equations that define failure. Bulbs fail due to hours of operation and voltage (temperature). Power cycling causing damage only when observation contradicts well proven science.

Same with a motherboard causing PSU failure. Long before PCs existed, all power supply outputs could be shorted together - without damage. Intel's ATX standards even defined how thick that shorting wire should be. A PSU damaged by the load (ie motherboard or shorting wire) was probably designed (or constructed) defectively.

In a market dominated by computer assemblers, then manufacturers can dump inferior PSUs into the market. Many would blame the load (ie motherboard), mythical surges, or 'dirty' electricity rather than a PSU that was defective when manufactured. Blame based only on observation and speculation.

Most failures are due to manufacturing defects. To say more requires identifying a specific reason for each failure. I have done that often to sometimes discover PSUs missing essential functions. Because PSUs are often marketed to people who do not even routinely demand spec sheets with each supply. No spec sheets mean it need not even meet national safety requirements, FCC regulations, or ATX standards. No spec numbers is a first symptom of missing essential functions. It may even self destruct on Intel's 'short all outputs together' test.

What caused a failure? A specific part in conjunction with how PSUs work is required for any valid conclusion. Most every PSU analyzed (by making it functional) failed due to manufacturing defects.

Spec sheets should include spec numbers that say it cannot damage the disk drive or motherboard. Required protection that might be missing IF written specifications do not say it exists. Conclusions only from observation (also called wild speculation) do not say why failures happen. If the PSU is properly designed, then it does not damage disk drives. And the load (motherboard or even a short circuit) does not damage the PSU.

Failing capacitors do not damage electronics. But it does explain strange and intermittent problems that some even blame on a virus (software) or surges. Speculation based only in observation is classic junk science. The load does not damage a properly designed PSU - as was standard long before PCs existed.
 




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