Help with Cooling Fan (Question)

[UCLAN]

Congratulations, you've stated nothing new and nothing that
supports your erroneous guess yet, but let's keep reading
and see how much more BS you'll spew...

Just explaining how the circuit operates for those of *YOU*
that don't understand it.

So it's news that a chip only operates when it's supply is
above a minimal threshold? I hate to break it to you, but
these are basic facts that you might as well just skip over
as they only show stupidity in coverage instead of just
skipping right to the part where you were wrong.

Problem is, kony, I don't know how basic I must get with *YOU.*
Past posts of yours suggest that you _need_ basic circuit
explanation.

you can't have it both ways... previously you tried to claim
the psu won't drain, yet it has to if the 5VSB diminishes,
because it does, in fact, no longer run from a 60Hz
transformer. You don't want to be bothered with facts
though, you learned one idea a long time ago and your closed
mind prevented any further learning since then.

Either way you lose, kony. If the 300v buss discharges "in a
few seconds" as you insist, your advice of pushing the ON/OFF
switch will have no effect (since the buss was already discharged.)
If the +5vsb is 60hz transformer based, it will drop to below the
Vcc cutoff point rather quickly (the ATX specs say 17ms, minimum)
so the PS_ON circuit will quickly be impotent. Pushing the ON/OFF
switch will have no effect here, either.

I have never claimed that "the psu won't drain" (I never use the
word drain), I merely stated that 300v bus discharge time varies
with design. You have been caught twice now making erroneous
statements. Care to try for three?

Randomly order a power supply
from Newegg right now- bet you it doesn't drain the 5VSB in
a few dozen ms.

Never said it would. I merely stated that was the minimum time based on
the ATX specification. The actual time would be dependent on +5vsb load
and +5vsb circuit capacitance.

Has nothing to do with belief, has to do with the simplest
of tests- voltage measurement.

So are you stating that you have performed these tests, and that
pushing the ON/OFF switch after unplugging an ATX PSU actually
affected the 300v buss? I think you're "embellishing" again, kony.

 

[kony]

Why is this in quotes? It is the first time you have uttered this
disclaimer. Don't hurt yourself back stepping.

It's in quotes because you seem to be confused about what I
do and don't write. Yes, it's the first time I wrote that
specific string of words, but more importantly, I had never
stated the opposite. Perhaps you need to step back and
consider that if you need to assume someone meant something
not written to make an argument, you had no argument to
make.

You insisted that an ATX PSU would have a faster discharging 300v
buss circuit regardless of the type of +5vsb circuit.

No, you imagined that I did.

This can only
mean that you thought that a 60hz transformer fed +5vsb circuit
somehow discharged the 300v buss circuit.

No it can only mean that after you let your imagination run
away, you were utterly lost and not participating in a
normal conversation anymore but rather a delusion.

Now, in your latest post,
you have added the caveat "almost always." Covering your tracks?

Funny, since almost every single learn of supposed-knowledge
you tried to share was in error.

No, simply trying to help you understand your complete
blunder, by continuing to elaborate. Your logical fallacies
abound and so I took pity in trying to make it as easy for
you to understand as possible, several times and yet still
you have no grasp.

Heh. Nice snip.

It is not a snip at all, it is the exact quote _you_ snipped
to provide previously.

I wasn't really trying to keep track, but this on top of
over a half-dozen other errors is looking pretty poorly, are
you sure you are of sound mind?

Doesn't really matter though, anyone out there with an ATX
supply and basic skill using a multimeter can confirm what I
have written. What you think I wrote, well that's between
you and the voices in your head to work out.

 

[kony]

Either way you lose, kony. If the 300v buss discharges "in a
few seconds" as you insist, your advice of pushing the ON/OFF
switch will have no effect (since the buss was already discharged.)

Wrong, either way I'm right:

The moment the PSU is unplugged from AC, it begins
discharging. If the system load is light, it will take a
very few (typically under 10 seconds) to discharge enough
that the system logic won't be functional.

If the system puts a heavier load on 5VSB, the inteval in
which the system logic is still functional decreases.

Either way, you're wrong. It will NOT be discharged within
a few dozen ms, nor will it not drain, it will do as I
described, drain over a period that, IF the system power
switch were pressed before it had drained enough, would
cause an attempt to power on the rest of the PSU circuitry
which rapidly drains the remaining charge in the caps. They
would have drained anyway, within a few seconds, but do so
even sooner.

This a VERY easy to see, again a situation where anyone who
has experience and bothers to take voltage readings can see
it clearly.

You are clueless.

If the +5vsb is 60hz transformer based,

Talk about an idiot.
You continue mentioning 60Hz transformer when that is not
used anymore and was rare even in the beginning.

it will drop to below the
Vcc cutoff point rather quickly (the ATX specs say 17ms, minimum)
so the PS_ON circuit will quickly be impotent. Pushing the ON/OFF
switch will have no effect here, either.

IF it were based a that design which nobody uses, yes you
would be correct. That isn't used, and your initial error
in assuming it was, made your following presumption about
what would happen, erroneous.

I have never claimed that "the psu won't drain" (I never use the
word drain), I merely stated that 300v bus discharge time varies
with design. You have been caught twice now making erroneous
statements. Care to try for three?

You wrote "I always kept a 47K bleed resistor handy when
playing with _any_ SMPS, AT or ATX."

That makes it very clear that you have no clue it isn't
necessary to drain them because by the time you've reached
over and grabbed your bleed resistor, there is nothing to
bleed!

Never said it would. I merely stated that was the minimum time based on
the ATX specification. The actual time would be dependent on +5vsb load
and +5vsb circuit capacitance.

BS, you were basing your argument around it.

So are you stating that you have performed these tests, and that
pushing the ON/OFF switch after unplugging an ATX PSU actually
affected the 300v buss? I think you're "embellishing" again, kony.

Never embellished in the first place, you were just too
thick to accept that there is more to it than you had
guessed. You did what far too many do, made a false
presumption then built a house of cards upon it.

Further, you now assume everyone else makes up BS as they go
along. Isn't it a realy strong clue that when I'd suggested
all along that you do the test, that I already knew what the
result would be through same test?


Since it seems you are completely hopeless, I see no reason
to carry on with this thread. Naturally you will try to
claim I'm wrong but it seems of no concern since you don't
even have a clue about the very points we're aguing. Just
to end the thread on a positive note I include the following
data:

=======================

Channel Well CWT-420ATX12 Power Supply
ATX rev. 2.03, 420W
AKA- Antec 400W PP-412
System- miniATX, ECS P6STP-FN board, P3-933 skt 370 based.

119.6 ACV, 326.4 DCV
5VSB with AC connected, no load (no system)= 5.11V
AC Plug Pulled, time till collapse = 11 seconds

5VSB with AC connected, system as load = 5.08V
AC Plug Pulled, time till collapse = 7 seconds
5VSB remained at 5.08 until then.

When AC plug is pulled and 1 second allowed to elapse before
the system (case) front power button pressed, the PSU 12V
rail is now first energized as evidenced by the rear exhaust
fan beginning to spin from prior off state and less than one
second more elapsed until voltage collapsed, when it would
have otherwise taken 7 seconds as observed above with no
change in test or measurement method, only pressing front
power button. 326V DC also quickly collapsed, a moment
(fractions of a second) before 5VSB did. Without any
logging equipment in front of me I can't give an exact ms
figure but deviation is definitely far less than 1/2 second,
probably under 1/4 second.

Above is described AS I did it, not some hypothetical
belief. Since the system used was only a light load on
5VSB, it is expected one more modern, particularly with 5VSB
jumperd to power PS2 or USB devices on the board would
drain faster, decreasing the interval when pressing system
power button would make a difference but not eliminating it
from doing so.

Maybe you know some who aren't hands on, but that does not
mean all are. This IS a hardware forum and hands-on is what
it's all about.

I invite you to gather your own data, I see no point in
further bickering over this so digest the data however you
want, it seems pretty clear to me and I will not argue this
any longer.

 

[UCLAN]

It's in quotes because you seem to be confused about what I
do and don't write. Yes, it's the first time I wrote that
specific string of words, but more importantly, I had never
stated the opposite.

From Message-ID: <[email protected]>

UCLAN:
ATX supplies are no different from AT supplies when it comes to
the discharge rate of the 300v buss. It varies with design. I
always kept a 47K bleed resistor handy when playing with _any_
SMPS, AT or ATX.

kony:
Yes they are different! Surely I dont need to tell you why?
Hint: 5VSB

If you had written "They are different some (or most, even) of the
time" you would have been in agreement with my "It varies with design,"
I would have probably agreed, and this would have been a very short
thread. But you didn't. You had to argue your point. Now you wanna
change your statement and agree with me. Fair enough.

 

[UCLAN]

Wrong, either way I'm right:

The moment the PSU is unplugged from AC, it begins
discharging. If the system load is light, it will take a
very few (typically under 10 seconds) to discharge enough
that the system logic won't be functional.

And pushing the ON/OFF button will do nothing.

If the system puts a heavier load on 5VSB, the inteval in
which the system logic is still functional decreases.

And pushing the ON/OFF button will do nothing, sooner.

Either way, you're wrong.

Looks like I'm right. Pushing the ON/OFF switch will do nothing
after a second or so.

It will NOT be discharged within
a few dozen ms,

Nobody said it would. Reading dysfunction affecting you again?

nor will it not drain, it will do as I
described, drain over a period that, IF the system power
switch were pressed before it had drained enough, would
cause an attempt to power on the rest of the PSU circuitry
which rapidly drains the remaining charge in the caps. They
would have drained anyway, within a few seconds, but do so
even sooner.

Oops, above you said "under 10 seconds." Now you're back to saying
"a few seconds." So the person must remove AC power from the PSU,
then - within a few seconds - press the ON/OFF switch for it to
have an effect on the 300v buss?

And you seem to have forgotten completely about holdover time or
low AC line dropout. Once the AC reaches a low level, the control
circuitry must shut down the switching process to prevent damage
to the PSU. This is part of the ATX spec. The 300v buss is at *roughly*
150vdc when this occurs (depending on design.) At this point, pulling
the PS_ON pin low will NOT turn on the PSU, and have NO effect on the
300v buss. So this significantly reduces your "few seconds" even
further.

You are clueless.

Pot -> Kettle -> Black

So if you are saying that pushing the ON/OFF switch *within a second
or two* of pulling the AC cord helps discharge the 300v buss, you might
be right on some supplies, but somehow I don't think that is what
"itsacin" was referring to when he wrote "My professor instructed us
to fist unplug the ps and then push the power button for a couple of
seconds to drain whatever power might be in there." That is, after all,
what you replied to. If he waits more than a couple of seconds, it will
have NO effect. And there will *still* be more than 100v on the 300v
buss.

Get out the bleeder resistor.