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Power supply, but no power???

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Anonymous
a b V Motherboard
a b ) Power supply
April 7, 2005 5:28:25 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

I believe a power surge toasted my power supply the other day, so I
replaced it with a new 350W ATX PSU. After removing the burnt psu, I
screwed the new psu into the case, hooked the ATX power supply to the
motherboard, and hooked up power for various components (HD's,
CD-ROM's). The motherboard's pilot light turns on to signify that it's
getting power, but when I press the case's power button... nothing. No
fans, no sound, no disk spinning, no signs of life at all (besides that
pilot light being on). Am I forgetting something?

I inspected all the components (and the motherboard and cpu) and none
of them appear (or smell) to have been damaged.

Where do I go from here? Any help would be appreciated.

Motherboard: DFI AK70 (AMD 750 cpu).

-U.

PS, forgive the cross-post -- I don't have a news host and google is
giving me errors when I try to post to some of these groups
individually.

More about : power supply power

Anonymous
a b V Motherboard
a b ) Power supply
April 8, 2005 12:15:25 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

If the power supply is toasted, then you have an important
fact. What inside the power supply is blackened? However if
just assuming it was some surge and if assuming it was the
power supply, then you have much to learn. The power supply
'system' is many components. A power supply is only one
part. You could swap things forever until something works.
Or discover in but two minutes what is and is not damaged.

Procedures and concepts are provided in two previous posts:
"Computer doesnt start at all" in alt.comp.hardware on 10
Jan 2004 at
http://tinyurl.com/2t69q and
"I think my power supply is dead" in alt.comp.hardware on 5
Feb 2004 at
http://tinyurl.com/yvbw9

Just because a light is on does not mean sufficient voltage
is available. Lights can illuminate; fans spin; and still the
power supply is not working. But then a power supply might
shutdown because something else is defective. There is no
faster analysis than using a 3.5 digit multimeter. Two
minutes should suggest what is defective. Furthermore,
numbers that mean nothing to you could be the 'smoking gun'
solution for those with better knowledge. Without numbers,
you cannot tap the best sources on the other side of your
computer screen.

"U. Cortez" wrote:
> I believe a power surge toasted my power supply the other day, so I
> replaced it with a new 350W ATX PSU. After removing the burnt psu, I
> screwed the new psu into the case, hooked the ATX power supply to the
> motherboard, and hooked up power for various components (HD's,
> CD-ROM's). The motherboard's pilot light turns on to signify that it's
> getting power, but when I press the case's power button... nothing. No
> fans, no sound, no disk spinning, no signs of life at all (besides that
> pilot light being on). Am I forgetting something?
>
> I inspected all the components (and the motherboard and cpu) and none
> of them appear (or smell) to have been damaged.
>
> Where do I go from here? Any help would be appreciated.
>
> Motherboard: DFI AK70 (AMD 750 cpu).
Anonymous
a b V Motherboard
a b ) Power supply
April 8, 2005 1:03:48 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

On Thu, 07 Apr 2005 13:28:25 -0700, U. Cortez wrote:

> I believe a power surge toasted my power supply the other day, so I
> replaced it with a new 350W ATX PSU. After removing the burnt psu, I
> screwed the new psu into the case, hooked the ATX power supply to the
> motherboard, and hooked up power for various components (HD's,
> CD-ROM's). The motherboard's pilot light turns on to signify that it's
> getting power, but when I press the case's power button... nothing. No
> fans, no sound, no disk spinning, no signs of life at all (besides that
> pilot light being on). Am I forgetting something?
>
> Where do I go from here? Any help would be appreciated.
>
Double check the power button plug is plugged into the proper pins. If it
is and it still doesn't work, unplug it and short the 2 power button pins
on the MB for a second. It should turn on power. If not, then it may be a
bad MB or bad PSU. If it does come on that way, then the problem is in the
leads to, or the power button itself.

--
Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
My server http://wesnewell.no-ip.com/cpu.php
Verizon server http://mysite.verizon.net/res0exft/cpu.htm
Related resources
Anonymous
a b V Motherboard
a b ) Power supply
April 8, 2005 1:03:49 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

Wes Newell <w.newell@TAKEOUTverizon.net> wrote in message news:<pan.2005.04.07.21.06.50.364178@TAKEOUTverizon.net>...
> On Thu, 07 Apr 2005 13:28:25 -0700, U. Cortez wrote:
>
> > I believe a power surge toasted my power supply the other day, so I
> > replaced it with a new 350W ATX PSU. After removing the burnt psu, I
> > screwed the new psu into the case, hooked the ATX power supply to the
> > motherboard, and hooked up power for various components (HD's,
> > CD-ROM's). The motherboard's pilot light turns on to signify that it's
> > getting power, but when I press the case's power button... nothing. No
> > fans, no sound, no disk spinning, no signs of life at all (besides that
> > pilot light being on). Am I forgetting something?
> >
> > Where do I go from here? Any help would be appreciated.
> >
> Double check the power button plug is plugged into the proper pins. If it
> is and it still doesn't work, unplug it and short the 2 power button pins
> on the MB for a second. It should turn on power. If not, then it may be a
> bad MB or bad PSU. If it does come on that way, then the problem is in the
> leads to, or the power button itself.

try taking all of the components out of your computer and runniong the
system out of the case, at least this mught remove the chance that
something is grounded.
Anonymous
a b V Motherboard
a b ) Power supply
April 8, 2005 12:13:24 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

> If the power supply is toasted, then you have an important
> fact. What inside the power supply is blackened?

Just for kicks, I opened up the old psu and it looks like a couple
capacitors blew. I'm not going to be all that dissappointed to see
that psu taken to the morgue, as it was old and cheap and possibly
under-powered. However, I won't be a happy puppy if my motherboard got
toasted too. I'll probably test it today and see...

-U.
Anonymous
a b V Motherboard
a b ) Power supply
April 8, 2005 4:22:21 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

The failed capacitors (and probably failed diodes) is
consistent with the circuit breaker tripping. Now here is
where we discover the technical knowledge of the guy who
selected that supply. Asian manufacturers have learned there
are many computer assemblers masguading as electrically
knowledgeable. So power supplies that are missing essential
functions are now dumped into the market at greater profit.
You know them by their lower price. These are functions where
were defacto standard even 30 years ago.

Any power supply that fails must not damage any other
computer part. But if the essential function was missing in
that supply, then you now may have other damage. A minimally
acceptable supply sells for about $65 full retail. Supplies
missing essential functions such as overvoltage protection
sell for less, earn greater profits for their manufacturers,
and can then cause disk drive and motherboard failure.

You have no other failures inside the computer IF the
original power supply was minimally acceptable; not selected
by a 'bean counting' computer assembler.

"U. Cortez" wrote:
> Just for kicks, I opened up the old psu and it looks like a couple
> capacitors blew. I'm not going to be all that dissappointed to see
> that psu taken to the morgue, as it was old and cheap and possibly
> under-powered. However, I won't be a happy puppy if my motherboard got
> toasted too. I'll probably test it today and see...
>
> -U.
Anonymous
a b V Motherboard
a b ) Power supply
April 8, 2005 8:13:57 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

It sounds like the power surge also toasted your motherboard. This
frequently happens when an inexpensive power supply unit is used in a
system. It passes the surge on to the motherboard, rather than absorb it
entirely.

--
DaveW



"U. Cortez" <goodbadskinnee@yahoo.com> wrote in message
news:1112905705.124652.269770@f14g2000cwb.googlegroups.com...
>I believe a power surge toasted my power supply the other day, so I
> replaced it with a new 350W ATX PSU. After removing the burnt psu, I
> screwed the new psu into the case, hooked the ATX power supply to the
> motherboard, and hooked up power for various components (HD's,
> CD-ROM's). The motherboard's pilot light turns on to signify that it's
> getting power, but when I press the case's power button... nothing. No
> fans, no sound, no disk spinning, no signs of life at all (besides that
> pilot light being on). Am I forgetting something?
>
> I inspected all the components (and the motherboard and cpu) and none
> of them appear (or smell) to have been damaged.
>
> Where do I go from here? Any help would be appreciated.
>
> Motherboard: DFI AK70 (AMD 750 cpu).
>
> -U.
>
> PS, forgive the cross-post -- I don't have a news host and google is
> giving me errors when I try to post to some of these groups
> individually.
>
Anonymous
a b V Motherboard
a b ) Power supply
April 8, 2005 9:19:23 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

On Fri, 08 Apr 2005 12:22:21 -0400, w_tom wrote:

> Any power supply that fails must not damage any other
> computer part. But if the essential function was missing in
> that supply, then you now may have other damage. A minimally
> acceptable supply sells for about $65 full retail. Supplies
> missing essential functions such as overvoltage protection
> sell for less, earn greater profits for their manufacturers,
> and can then cause disk drive and motherboard failure.
>
I think overload protection is a requirement for UL approval. And I've
never spent over $24 for a PSU.:-)

I've used a 600W similar to this for over a year now on my A64 system. But
it was $24 when I bought mine.

http://store.mrtechus.com/60ulapatxcop.html

--
Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
My server http://wesnewell.no-ip.com/cpu.php
Verizon server http://mysite.verizon.net/res0exft/cpu.htm
Anonymous
a b V Motherboard
a b ) Power supply
April 9, 2005 4:26:52 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

Well last night I tested the power supply (with it just plugged into
the motherboard) and all the voltages were in their acceptable ranges.
So, I started to plug things back in 1 at a time, and... it all
worked! I'm typing this now on my working computer. There must have
just been a loose connection or something when I first installed my new
PSU. But when I took my computer apart (yes, I mean completely apart
-- even took the cooler off the cpu) and put it back together I must
have secured whatever was keeping it from starting up before.

So I guess the failed motherboard was a false alarm (whew!). Now the
first thing on my agenda: get a UPS so I don't have to worry about
circuit trips blowing my PSU again.

Thanks all for the help!

-U.
Anonymous
a b V Motherboard
a b ) Power supply
April 10, 2005 10:07:31 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

Overvoltage protection is not required for UL approval -
obviously.

First, power supplies selling for $25 retail would quickly
forget that essential function. If is contains essential
functions such as overvoltage protection, then the
manufacturer would proudly note that function - and many
others. If is does not list overvoltage protection (as with
most sub $40 supplies), then it will also forget to install
overvoltage protection and many other essential functions.

Second, just not possible to sell a supply at $25 retail,
earn a profit, and include essential functions.

Third, UL only cares about you getting hurt. UL does not
care for an instant how destructive that power supply is to
any transistors. Overvoltage protection does nothing for
human safety.

Fourth, then there is the common problem with counterfeit UL
stickers. No way a $25 supply is going to include functions
considered essential even 30 years ago.

Wes Newell wrote:
> On Fri, 08 Apr 2005 12:22:21 -0400, w_tom wrote:
>> Any power supply that fails must not damage any other
>> computer part. But if the essential function was missing in
>> that supply, then you now may have other damage. A minimally
>> acceptable supply sells for about $65 full retail. Supplies
>> missing essential functions such as overvoltage protection
>> sell for less, earn greater profits for their manufacturers,
>> and can then cause disk drive and motherboard failure.
>
> I think overload protection is a requirement for UL approval. And I've
> never spent over $24 for a PSU.:-)
>
> I've used a 600W similar to this for over a year now on my A64
> system. But it was $24 when I bought mine.
>
> http://store.mrtechus.com/60ulapatxcop.html
Anonymous
a b V Motherboard
a b ) Power supply
April 10, 2005 10:07:54 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

Problem could even been created by a motherboard standoff
shorted through solder mask. Example of why one does not swap
parts. You fixed (permanently or temporarily) the problem and
don't even know why it existed. In the future, get the
numbers before disassembling anything. At least we would have
a much short list of suspects. If failure is seen on meter,
then you could disconnect some things and test until the
problem is resolved. Knowing which voltage was problematic
could have also been more helpful.

Just a better way to approach the problem next time.
Historically, such intermittents tend to return slightly more
often than not.

"U. Cortez" wrote:
> Well last night I tested the power supply (with it just plugged into
> the motherboard) and all the voltages were in their acceptable ranges.
> So, I started to plug things back in 1 at a time, and... it all
> worked! I'm typing this now on my working computer. There must have
> just been a loose connection or something when I first installed my new
> PSU. But when I took my computer apart (yes, I mean completely apart
> -- even took the cooler off the cpu) and put it back together I must
> have secured whatever was keeping it from starting up before.
>
> So I guess the failed motherboard was a false alarm (whew!). Now the
> first thing on my agenda: get a UPS so I don't have to worry about
> circuit trips blowing my PSU again.
>
> Thanks all for the help!
>
> -U.
Anonymous
a b V Motherboard
a b ) Power supply
April 10, 2005 11:47:42 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

On Fri, 08 Apr 2005 17:19:23 GMT, Wes Newell
<w.newell@TAKEOUTverizon.net> put finger to keyboard and composed:

>On Fri, 08 Apr 2005 12:22:21 -0400, w_tom wrote:
>
>> Any power supply that fails must not damage any other
>> computer part. But if the essential function was missing in
>> that supply, then you now may have other damage. A minimally
>> acceptable supply sells for about $65 full retail. Supplies
>> missing essential functions such as overvoltage protection
>> sell for less, earn greater profits for their manufacturers,
>> and can then cause disk drive and motherboard failure.
>>
>I think overload protection is a requirement for UL approval. And I've
>never spent over $24 for a PSU.:-)
>
>I've used a 600W similar to this for over a year now on my A64 system. But
>it was $24 when I bought mine.

>http://store.mrtechus.com/60ulapatxcop.html

I'd be suspicious of that 600W rating. The combined output of the 3
major rails is 644W, a figure that doesn't appear to allow for proper
derating. If it's a Deer brand PSU, I'd be looking especially closely
at it. I've been stung by a 170W fake labelled as 400W.

Here are the claimed specs from the above URL:

===================================================================
ATX 600 Watt Power Supply for P4 ,PIII and AMD processor compatible
with ATX 2.03 standard.

DC Output:

+5V 50A +/-5% +3.3V 32A +/-4% +12V 24A +/-5%

-12V 1.0A +/-10% -5V 0.5A +/-10% +5Vsb 2.0A +/-5%
===================================================================

Having said the above, I'd be willing to bet that the PSU in a typical
system is never called upon to provide more than about 150W.

Until my recent experience with the fake PSU, I've always been well
served by generics. In fact, I contacted a dozen or so computer stores
in my area and was unable to find a single vendor who could supply
anything other than a generic ATX PSU. Most were selling Deers. I had
to go online to find a branded PSU.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Anonymous
a b V Motherboard
a b ) Power supply
April 10, 2005 2:20:05 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

I think you both have a point. I have no doubt that there are cheap
psu's out there that completely ignore the need for overvoltage
protection. On the contrary, there are probably some inexpensive psu's
that have the protection. While it appears that the psu that wes found
does have protection, I'd still be a little skeptical of a psu that
claims to push 600w but only cost $18. Personally, I'll stick with
name-brand psu's.
Anonymous
a b V Motherboard
a b ) Power supply
April 10, 2005 3:38:53 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

On Sun, 10 Apr 2005 06:07:31 -0400, w_tom wrote:

> Overvoltage protection is not required for UL approval -
> obviously.
>
If you say so.
>
> Second, just not possible to sell a supply at $25 retail,
> earn a profit, and include essential functions.
>
So, you don't think they could spent an extra 25 cents to do this in a $25
PSU. Interesting.

> Third, UL only cares about you getting hurt. UL does not
> care for an instant how destructive that power supply is to any
> transistors. Overvoltage protection does nothing for human safety.
>
Again, if you say so.

> Fourth, then there is the common problem with counterfeit UL
> stickers. No way a $25 supply is going to include functions considered
> essential even 30 years ago.
>
Well, This psu says it has overload protection, and I have no basis for
calling them liars. It's retail price is over $40, but it's sale price is
only $18. They also have a 300W unit that states it has overload
protection they sell for $9 (Retail price of $24).

http://store.mrtechus.com/60ulapatxcop.html

--
Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
My server http://wesnewell.no-ip.com/cpu.php
Verizon server http://mysite.verizon.net/res0exft/cpu.htm
Anonymous
a b V Motherboard
a b ) Power supply
April 10, 2005 7:25:34 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

Overload protection is another and different function
required of power supplies. Does that $25 supply really have
overload protection? The specs are quite clear about this.
Short all outputs together and turn on power. Power supply
must not be damaged. That demonstrates overload protection
which is completely different from overvoltage protection
which, in turn, has nothing to do with UL approval.

This is basic electrical knowledge that anyone should
understand before making power supply recommendations.
Overvoltage and overload (or overpower) protection are
completely different functions. Power supplies must meet
both, and other standards such as FCC. Just another standard
that many discounted power supplies may violate to sell at
profit.

Wes Newell wrote:
> On Sun, 10 Apr 2005 06:07:31 -0400, w_tom wrote:
>> Overvoltage protection is not required for UL approval -
>> obviously.
>
> If you say so.
>
>> Second, just not possible to sell a supply at $25 retail,
>> earn a profit, and include essential functions.
>
> So, you don't think they could spent an extra 25 cents to do this
> in a $25 PSU. Interesting.
>
>> Third, UL only cares about you getting hurt. UL does not
>> care for an instant how destructive that power supply is to any
>> transistors. Overvoltage protection does nothing for human safety.
>
> Again, if you say so.
>
>> Fourth, then there is the common problem with counterfeit UL
>> stickers. No way a $25 supply is going to include functions
>> considered essential even 30 years ago.
>
> Well, This psu says it has overload protection, and I have no basis
> for calling them liars. It's retail price is over $40, but it's
> sale price is only $18. They also have a 300W unit that states it
> has overload protection they sell for $9 (Retail price of $24).
>
> http://store.mrtechus.com/60ulapatxcop.html
Anonymous
a b V Motherboard
a b ) Power supply
April 11, 2005 10:41:58 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

On Sun, 10 Apr 2005 11:38:53 GMT, Wes Newell
<w.newell@TAKEOUTverizon.net> put finger to keyboard and composed:

>On Sun, 10 Apr 2005 06:07:31 -0400, w_tom wrote:
>
>> Overvoltage protection is not required for UL approval -
>> obviously.
>>
>If you say so.
>>
>> Second, just not possible to sell a supply at $25 retail,
>> earn a profit, and include essential functions.
>>
>So, you don't think they could spent an extra 25 cents to do this in a $25
>PSU. Interesting.

In fact the additional cost can be nil. Deer PSUs have a single IC
that does it all - PWM control, PS-ON control, +3.3V regulation,
+5/+12V regulation, Power Good generation, and overvoltage sensing.

See this circuit diagram:

"LC-B250ATX ch. Y-B200-ATX ver. 2.9 JNC Computer Co."
http://electro-tech.narod.ru/schematics/power/JNC_Y-B20...


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Anonymous
a b V Motherboard
a b ) Power supply
April 11, 2005 11:25:22 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

On Mon, 11 Apr 2005 06:41:58 +1000, Franc Zabkar
<fzabkar@optussnet.com.au> put finger to keyboard and composed:

>On Sun, 10 Apr 2005 11:38:53 GMT, Wes Newell
><w.newell@TAKEOUTverizon.net> put finger to keyboard and composed:
>
>>On Sun, 10 Apr 2005 06:07:31 -0400, w_tom wrote:
>>
>>> Overvoltage protection is not required for UL approval -
>>> obviously.
>>>
>>If you say so.
>>>
>>> Second, just not possible to sell a supply at $25 retail,
>>> earn a profit, and include essential functions.
>>>
>>So, you don't think they could spent an extra 25 cents to do this in a $25
>>PSU. Interesting.
>
>In fact the additional cost can be nil. Deer PSUs have a single IC
>that does it all - PWM control, PS-ON control, +3.3V regulation,
>+5/+12V regulation, Power Good generation, and overvoltage sensing.

Here is the data for an all-in-one IC (not the same as in the Deer
PSU):
http://www.systemgeneral.com/semiGP/sg6105_E.asp


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Anonymous
a b V Motherboard
a b ) Power supply
April 11, 2005 6:35:39 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

I don't see the overvoltage protection circuit anywhere in
that power supply at electro-tech.narod.ru . Overvoltage
protection means something must be able to short out a (about)
25 amp output with no damage. Not a cheap component and
definitely not possible inside an Integrated Circuit.

The IC SG6105 contains many functions previously performed
by multiple chips. This is a minor cost decrease. But, for
example, the galvanic isolation necessary for some of those
functions is not inside this chip either. Things such as
optocoupler are still another separate component.
Overvoltage protection is not a part of that chip. In fact,
Intel specs demand that overvoltage protection be part of a
separate circuit.

The SG6105 does contain circuits once provided by multiple
inexpensive components. A power supply once selling for less
than $100 now costs only $65 retail. Expensive components are
still required for other and necessary functions such as
overvoltage protection. Supplies containing necessary
functions such as overvoltage protection cannot sell for $25
retail at profit. Those would be supplies dumped into the
market missing essential functions.

Franc Zabkar wrote:
> In fact the additional cost can be nil. Deer PSUs have a single IC
> that does it all - PWM control, PS-ON control, +3.3V regulation,
> +5/+12V regulation, Power Good generation, and overvoltage sensing.
>
> See this circuit diagram:
>
> "LC-B250ATX ch. Y-B200-ATX ver. 2.9 JNC Computer Co."
> http://electro-tech.narod.ru/schematics/power/JNC_Y-B20...
Anonymous
a b V Motherboard
a b ) Power supply
April 12, 2005 9:02:59 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

On Mon, 11 Apr 2005 19:35:21 -0400, w_tom <w_tom1@hotmail.com> put
finger to keyboard and composed:

> Even in the very first IBM PC, power supply included that
>voltage monitoring function (that is now part of the single
>IC). A function completely different from the overvoltage
>protection circuit - which was also in that IBM PC. Some
>power supply controller failures can cause overvoltage.
>Totally unacceptable 30 years ago as today. The crowbar (or
>equivalent) is required today as it was 30 years ago on switch
>mode power supplies. Even the Intel spec (which is only for
>switch mode power supplies) says

>> The overvoltage sense circuitry and reference shall reside
>> in packages that are separate and distinct from the
>> regulator control circuitry and reference. No single point
>> fault shall be able to cause a sustained overvoltage
>> condition on any or all outputs. The supply shall provide
>> latch-mode overvoltage protection as defined below.

I understand that separating the two functions (OVS and OVP) gives
added security, but I can't see the need for a brute-force approach to
OVP. By this I mean that it is not necessary to clamp the output with
an expensive high-current zener or SCR - one can much more elegantly
achieve the same end, and still comply with Intel's spec, by turning
off the PWM controller, or by turning off its drive transistors. See
this DTK PSU which implements OVS, OVP and OPP with about $2 worth of
parts:

http://www.pavouk.comp.cz/hw/en_atxps.html

I have a 1000W minicomputer SMPS whose control module senses the
output and shuts off the oscillator in the event of an OV fault. There
are no expensive OVP parts, and this is in an SMPS that has 4 or 5
screw terminal capacitors the size of soft drink cans, stud mounted
diodes on massive heatsinks, four TO3 chopper transistors, and an AC
fan. The +5V cables (+5V @ 150A) are thick enough to start my car.

> Nothing new in this requirement. However when dumping
>product into a marketplace dominated by 'bean counter'
>mentalities, then profits are just too great. How to suspect
>a defective power supply? No long list of numerical
>specification and no specific listing of overvoltage
>protection? Then it is a power supply for the market of 'bean
>counting' computer assemblers.

Some TV sets use 130V protection zeners (eg R2M, R2KY, $1.85 retail)
on their 100-115V supply rails. These designs have no OVS. Ironically
it appears that the designers have chosen this sledgehammer approach
because it costs *less* than OVS. I'm not really comfortable with such
a design because its success depends on the failure mode of the
protection device. IME the zener always fails SC, and therefore
protects the TV, but if it fails OC (unlikely, but possible), then
there is no protection at all. Killing the oscillator would be much
safer. In fact, HV protection and beam current limiting is usually
implemented by shutting down the horizontal oscillator.

I guess a comparable analogy may be MOVs in "surge protected" power
boards. They may sacrificially absorb the first surge, but thereafter
they are useless.

> That schematic is further proof that many power supplies are
>missing essential functions.

Sorry, I don't see it. You state that the original IBM supplies had an
OVP circuit, but you don't elaborate. How exactly did they do this? I
have the original IBM AT Tech Ref Manual but it doesn't adequately
spell out the PSU spec. Can you recommend one upmarket PSU that
handles OVP by brute-forcing the output(s)?

> Some power supplies fail and
>then destroy computer peripherals.

True. I witnessed a discussion at aus.electronics where an SMPS failed
in such a manner that AC leaked into the DC side of the switchmode
transformer, causing catastrophic damage to the PC. I suggested that
an external crowbar circuit could provide protection against such
disasters but the responses were negative.

> A failure directly
>traceable to a human who buys on price rather than learn basic
>electrical principles. In a market where so many 'experts'
>don't even know how how electricity works, then many clone
>computers do have $25 power supplies.

What I find hard to comprehend is how even the upmarket ATX PSUs can
deliver their claimed power given the relative size of the components
in my 1000W SMPS. For example, when comparing the mains filter caps,
one is the size of a Coke can, the other is smaller than a C size
battery. Has technology really improved that much?


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Anonymous
a b V Motherboard
a b ) Power supply
April 12, 2005 9:03:00 PM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

You are assuming a power supply controller will see all
failures and then shutdown accordingly. What happens when
controller's feedback fails? A feedback circuit that will be
discussed again below. Power supply controller outputs more
power trying to raise a voltage that never rises. IOW power
supply has output excessive and destructive voltages. Just
another reason why "separate and distinct" overvoltage
protection has been required 30 years ago as it still is
required today.

Neither you nor I care how a particular power supply meets
this 'well proven to be necessary' OVP function. We don't
even care if the function uses a simple and easily constructed
crowbar or uses something different. The point remains a power
supply must provide that defined function. Schematic from
electro-tech.narod.ru quite obviously violates the industry
requirement. It has no overvoltage protection. It
demonstrates how power supplies are sold for well under $60
retail. They forget to include essential functions such as
OVP. That supply from http://electro-tech.narod.ru is
designed to be dumped into a market driven by 'bean counter'
engineering.

Provided were numeric specs for a supply that does provide
the OVP circuit. Back to the original point. Properly
designed supply does not and can not sell for $25 retail. So
how do others sell power supplies for $25 retail? They forget
to include required and necessary functions such as
Overvoltage Protection.

Is this done by a crowbar circuit or by some other means?
Neither you nor I care. Industry standards demand that OVP
function exist for 'long proven' necessary reasons. Some
supplies do provide such functions. But these minimally
acceptable supplies cannot sell for $25 retail - again
repeating the bottom line point.

In the meantime, that DTK PSU from www.pavouk.comp.cz
violates another essential function. The power supply must
provide galvanic isolation of at least 1000 volts. Therefore
the "Feedback" circuit must contain an optocoupler or
something equivalent. The DTK PSU has no such isolation. It
violates another industry standard. And so another essential
function would be 'forgotten'.

Earlier a power supply controller would output overvoltage
because the feedback circuit failed. Controller never knew it
was outputting excessive voltage. What feedback components?
Same optocoupler that is required with galvanic isolation.
Just another missing specification to sell at $25. Again the
point. Power supplies missing essential functions and
routinely dumped into the market because so many computer
assemblers don't even have basic electrical knowledge; never
learned about galvanic isolation, overvoltage protection,
feedback current limiting, or overpower protection.

When a computer assembler looks only at power and price,
then a game of specmanship is afoot. For example, a Dell or
HP power supply may claim only 250 watts. The 'bean counting'
computer assembler then claims that is woefully too small.
And yet if the same power supply was being marketed by others
to computer assemblers, then suddenly the same supply is rated
at 375 watts. Why? They don't list the output power. Rated
is maximum power that a power supply might consume. The 'bean
counting' computer assembler then declares the HP and Dell
supplies are undersized.

It gets even more interesting. A power supply must be
completely shorted out and still must not be damaged. And yet
here are power supplies, designed for a 'bean counter' market,
that self destruct even before reaching 100% load:
http://www6.tomshardware.com/howto/02q4/021021/index.ht...

First thing to look for in any power supply: if the supply
manufacturer does not provide a long list of numerical specs,
then bet it is a scam. More responsible power supply
manufacturers provide numerous numerical specs. One need not
even know what those specs mean. Just having written numerical
specs is a first requirement. Manufacturer commits; says to
the 1% who know technology that this supply does provide these
functions. However a manufacturer who is dumping inferior
supplies into a market of computer assemblers must disempower
the 1%. He must provide no written specifications. Then a
knowledgeable 1% cannot warn the other 99% of a defective
product.

Welcome to a world where so many power supplies don't
provide specs and are then recommended based only on the price
and watts.

#1 requirement for a power supply: it must provide a long
list of numeric specs. If that power supply does not
specifically state overvoltage protection, then another
essential function is missing.

We care less how he provides overvoltage protection. We
care more that he claims to provide OVP. That missing
function demonstrates why so many supplies sell for only $25
and $40 full retail.

Franc Zabkar wrote:
> On Mon, 11 Apr 2005 19:35:21 -0400, w_tom <w_tom1@hotmail.com> put
> finger to keyboard and composed:
> ...
>
> I understand that separating the two functions (OVS and OVP) gives
> added security, but I can't see the need for a brute-force approach to
> OVP. By this I mean that it is not necessary to clamp the output with
> an expensive high-current zener or SCR - one can much more elegantly
> achieve the same end, and still comply with Intel's spec, by turning
> off the PWM controller, or by turning off its drive transistors. See
> this DTK PSU which implements OVS, OVP and OPP with about $2 worth of
> parts:
>
> http://www.pavouk.comp.cz/hw/en_atxps.html
>
> I have a 1000W minicomputer SMPS whose control module senses the
> output and shuts off the oscillator in the event of an OV fault. There
> are no expensive OVP parts, and this is in an SMPS that has 4 or 5
> screw terminal capacitors the size of soft drink cans, stud mounted
> diodes on massive heatsinks, four TO3 chopper transistors, and an AC
> fan. The +5V cables (+5V @ 150A) are thick enough to start my car.
> ...
>
> Some TV sets use 130V protection zeners (eg R2M, R2KY, $1.85 retail)
> on their 100-115V supply rails. These designs have no OVS. Ironically
> it appears that the designers have chosen this sledgehammer approach
> because it costs *less* than OVS. I'm not really comfortable with such
> a design because its success depends on the failure mode of the
> protection device. IME the zener always fails SC, and therefore
> protects the TV, but if it fails OC (unlikely, but possible), then
> there is no protection at all. Killing the oscillator would be much
> safer. In fact, HV protection and beam current limiting is usually
> implemented by shutting down the horizontal oscillator.
>
> I guess a comparable analogy may be MOVs in "surge protected" power
> boards. They may sacrificially absorb the first surge, but thereafter
> they are useless.
> ...
>
> Sorry, I don't see it. You state that the original IBM supplies had an
> OVP circuit, but you don't elaborate. How exactly did they do this? I
> have the original IBM AT Tech Ref Manual but it doesn't adequately
> spell out the PSU spec. Can you recommend one upmarket PSU that
> handles OVP by brute-forcing the output(s)?
> ...
>
> True. I witnessed a discussion at aus.electronics where an SMPS failed
> in such a manner that AC leaked into the DC side of the switchmode
> transformer, causing catastrophic damage to the PC. I suggested that
> an external crowbar circuit could provide protection against such
> disasters but the responses were negative.
> ...
>
> What I find hard to comprehend is how even the upmarket ATX PSUs can
> deliver their claimed power given the relative size of the components
> in my 1000W SMPS. For example, when comparing the mains filter caps,
> one is the size of a Coke can, the other is smaller than a C size
> battery. Has technology really improved that much?
>
> - Franc Zabkar
September 1, 2005 4:57:48 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

"U. Cortez" <goodbadskinnee@yahoo.com> said

>I believe a power surge toasted my power supply the other day, so I
>replaced it with a new 350W ATX PSU. After removing the burnt psu, I
>screwed the new psu into the case, hooked the ATX power supply to the
>motherboard, and hooked up power for various components (HD's,
>CD-ROM's). The motherboard's pilot light turns on to signify that it's
>getting power, but when I press the case's power button... nothing. No
>fans, no sound, no disk spinning, no signs of life at all (besides that
>pilot light being on). Am I forgetting something?
>
>I inspected all the components (and the motherboard and cpu) and none
>of them appear (or smell) to have been damaged.
>
>Where do I go from here? Any help would be appreciated.
>
>Motherboard: DFI AK70 (AMD 750 cpu).
>
>-U.
>
>PS, forgive the cross-post -- I don't have a news host and google is
>giving me errors when I try to post to some of these groups
>individually.
September 1, 2005 8:00:04 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

Jon wrote:
> "U. Cortez" <goodbadskinnee@yahoo.com> said
>
>
>>I believe a power surge toasted my power supply the other day, so I
>>replaced it with a new 350W ATX PSU. After removing the burnt psu, I
>>screwed the new psu into the case, hooked the ATX power supply to the
>>motherboard, and hooked up power for various components (HD's,
>>CD-ROM's). The motherboard's pilot light turns on to signify that it's
>>getting power, but when I press the case's power button... nothing. No
>>fans, no sound, no disk spinning, no signs of life at all (besides that
>>pilot light being on). Am I forgetting something?
>>
>>I inspected all the components (and the motherboard and cpu) and none
>>of them appear (or smell) to have been damaged.
>>
>>Where do I go from here? Any help would be appreciated.
>>
>>Motherboard: DFI AK70 (AMD 750 cpu).
>>
>>-U.
>>
>>PS, forgive the cross-post -- I don't have a news host and google is
>>giving me errors when I try to post to some of these groups
>>individually.
>
>
If your MB has the 4-pin (square) auxiliary power connector, and you
haven't connected it, you will get that result.

Another possibility is that, while changing the PS, you accidentally
disconnected the power button connector. It's small and easy to
pull off its header.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
a b V Motherboard
a b ) Power supply
September 2, 2005 3:39:16 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

On Thu, 01 Sep 2005 04:00:04 GMT, in comp.sys.ibm.pc.hardware.systems,
CJT <abujlehc@prodigy.net> wrote:

>Jon wrote:
>> "U. Cortez" <goodbadskinnee@yahoo.com> said
>>
>>>I believe a power surge toasted my power supply the other day, so I
>>>replaced it with a new 350W ATX PSU. After removing the burnt psu, I
>>>screwed the new psu into the case, hooked the ATX power supply to the
>>>motherboard, and hooked up power for various components (HD's,
>>>CD-ROM's). The motherboard's pilot light turns on to signify that it's
>>>getting power, but when I press the case's power button... nothing. No
>>>fans, no sound, no disk spinning, no signs of life at all (besides that
>>>pilot light being on). Am I forgetting something?
>>>
>>>I inspected all the components (and the motherboard and cpu) and none
>>>of them appear (or smell) to have been damaged.
>>>
>>>Where do I go from here? Any help would be appreciated.
>>>
>>>Motherboard: DFI AK70 (AMD 750 cpu).
>>>
>>>-U.
>>>
>>>PS, forgive the cross-post -- I don't have a news host and google is
>>>giving me errors when I try to post to some of these groups
>>>individually.
>>
>If your MB has the 4-pin (square) auxiliary power connector, and you
>haven't connected it, you will get that result.
>
>Another possibility is that, while changing the PS, you accidentally
>disconnected the power button connector. It's small and easy to
>pull off its header.

A mistake people make every now and then (including myself, and I've
assembled lots of computers) is to set the FDD power connector one
step to the side (only connecting three of the four pins), and this
will cause a shortcut.

Another possibility is that something else is dead too. All defects
aren't visible to the naked eye...

Disconnect all power cables except the one to the motherboard, and
also disconnect the IDE and FDD cables (a defective drive can prevent
a computer from starting).

Then try to start the comp again.

If it works now, start reconnecting components one by one, and do a
test start between each...

If it doesn't start even with all drives etc disconnected, your mobo
might be fried. Or maybe your new PSU is defective too. Or something
else...

--
May all spammers die in horrible pains!
Wanna e-mail me? Well, peter_e is correct, but the rest is obviously bogus...
Try algonet in the .se TLD instead.
Anonymous
a b V Motherboard
a b ) Power supply
September 2, 2005 3:39:17 AM

Archived from groups: alt.comp.periphs.mainboard,comp.sys.ibm.pc.hardware.systems,comp.hardware (More info?)

"Peter Emanuelsson" <peter_e@may.all.spammers.die> wrote in message
news:xXIXQ+jEVF=leCalcEFcICI2GntL@4ax.com...
> On Thu, 01 Sep 2005 04:00:04 GMT, in comp.sys.ibm.pc.hardware.systems,
> CJT <abujlehc@prodigy.net> wrote:
>
>>Jon wrote:
>>> "U. Cortez" <goodbadskinnee@yahoo.com> said
>>>
>>>>I believe a power surge toasted my power supply the other day, so I
>>>>replaced it with a new 350W ATX PSU. After removing the burnt psu, I
>>>>screwed the new psu into the case, hooked the ATX power supply to the
>>>>motherboard, and hooked up power for various components (HD's,
>>>>CD-ROM's). The motherboard's pilot light turns on to signify that it's
>>>>getting power, but when I press the case's power button... nothing. No
>>>>fans, no sound, no disk spinning, no signs of life at all (besides that
>>>>pilot light being on). Am I forgetting something?
>>>>
>>>>I inspected all the components (and the motherboard and cpu) and none
>>>>of them appear (or smell) to have been damaged.
>>>>
>>>>Where do I go from here? Any help would be appreciated.
>>>>
>>>>Motherboard: DFI AK70 (AMD 750 cpu).
>>>>
>>>>-U.
>>>>
>>>>PS, forgive the cross-post -- I don't have a news host and google is
>>>>giving me errors when I try to post to some of these groups
>>>>individually.
>>>
>>If your MB has the 4-pin (square) auxiliary power connector, and you
>>haven't connected it, you will get that result.
>>
>>Another possibility is that, while changing the PS, you accidentally
>>disconnected the power button connector. It's small and easy to
>>pull off its header.
>
> A mistake people make every now and then (including myself, and I've
> assembled lots of computers) is to set the FDD power connector one
> step to the side (only connecting three of the four pins), and this
> will cause a shortcut.
>
> Another possibility is that something else is dead too. All defects
> aren't visible to the naked eye...
>
> Disconnect all power cables except the one to the motherboard, and
> also disconnect the IDE and FDD cables (a defective drive can prevent
> a computer from starting).
>
> Then try to start the comp again.
>
> If it works now, start reconnecting components one by one, and do a
> test start between each...
>
> If it doesn't start even with all drives etc disconnected, your mobo
> might be fried. Or maybe your new PSU is defective too. Or something
> else...
>
> --
> May all spammers die in horrible pains!
> Wanna e-mail me? Well, peter_e is correct, but the rest is obviously
> bogus...
> Try algonet in the .se TLD instead.

On the back of the power supply, there is a switch where voltage can be set
to either 120 volts or 240 volts. Make sure it is set to the correct
voltage. This often overlooked.
!