Power supply fried, replaced it, computer won't start

Discussion in 'Computer Support' started by ., Aug 28, 2006.

  1. In article <>,
    "Rod Speed" <> wrote:

    > David Matthew Wood <> wrote
    >
    > >> Poor quality power supplies have two very nasty habits:

    >
    > >> 1) They die early (that is GUARANTEED, btw),
    > >> often shortly after leaving the factory
    > >> 2) With no built-in component protection, they often take other
    > >> components with them, when they die. In other words, cheap power
    > >> supplies kill motherboards, hard drives, CPUs, RAM, etc.

    >
    > >> Your post is about TWO poor quality power supplies. I suspect that
    > >> the first one died ungracefully, taking the motherboard out with it.
    > >> The second one can't even power itself, apparently.

    >
    > >> It's your money, but people don't seem to understand that often
    > >> spending an extra 40 bucks or so on a GOOD power supply can
    > >> save a complete rebuild, costing hundreds of bucks. -Dave

    >
    > > Actually, I'm sure the power supply he bought from the
    > > store is perfectly fine. Don't forget about "power good"!
    > > If the power supply doesn't see this, it will not stay on.

    >
    > You've got that backwards, its PROVIDED by the
    > power supply, not observed by the power supply.


    It works both ways. Yes, it is provided by the power supply, and yes,
    it is there to prevent the motherboard from starting up before the power
    supply stabilizes.

    However, on some power supplies, if there is a power surge or any other
    issue (which can be caused by a fried component on the motherboard),
    "Power Good" will also shut down the power supply if it malfunctions.
     
    David Matthew Wood, Aug 28, 2006
    #21
    1. Advertisements

  2. In article <>,
    wrote:

    > David Matthew Wood <> wrote:
    >
    > >
    > >> Poor quality power supplies have two very nasty habits:
    > >>
    > >> 1) They die early (that is GUARANTEED, btw), often shortly after leaving
    > >> the factory
    > >> 2) With no built-in component protection, they often take other
    > >> components
    > >> with them, when they die. In other words, cheap power supplies kill
    > >> motherboards, hard drives, CPUs, RAM, etc.
    > >>
    > >> Your post is about TWO poor quality power supplies. I suspect that the
    > >> first one died ungracefully, taking the motherboard out with it. The
    > >> second
    > >> one can't even power itself, apparently.
    > >>
    > >> It's your money, but people don't seem to understand that often spending
    > >> an
    > >> extra 40 bucks or so on a GOOD power supply can save a complete rebuild,
    > >> costing hundreds of bucks. -Dave

    >
    > >Actually, I'm sure the power supply he bought from the store is
    > >perfectly fine. Don't forget about "power good"! If the power supply
    > >doesn't see this, it will not stay on. That is how all ATX power
    > >supplies are designed, and it is indeed built-in component protection.
    > >If anything is shorting out (as could very well be the case here, since
    > >his first power supply fried something), it will shut down a working
    > >power supply.

    >
    > Good link on the Power Good Signal
    > http://www.pcguide.com/ref/power/sup/funcPowerGood-c.html
    > and how "Some extremely el-cheapo power supplies may "fake" the Power
    > Good signal by just tying it to another +5 V line."


    Yes, and while it doesn't directly have anything to do with Power Good,
    such power supplies don't provide any protection either. If you try to
    fire up a GOOD supply and it doesn't observe the correct loads (either
    from not being properly connected or from something that is shorting),
    it will shut down in order to prevent damage since it is bad for a power
    supply to run without a load. Same goes with amps. If you power up an
    amp and crank the volume without speakers attached, it will either a, go
    into thermal shut down, or b, self-destruct.
     
    David Matthew Wood, Aug 28, 2006
    #22
    1. Advertisements

  3. .

    Rod Speed Guest

    David Matthew Wood <> wrote
    > Rod Speed <> wrote
    >> David Matthew Wood <> wrote


    >>>> Poor quality power supplies have two very nasty habits:


    >>>> 1) They die early (that is GUARANTEED, btw),
    >>>> often shortly after leaving the factory
    >>>> 2) With no built-in component protection, they often take other
    >>>> components with them, when they die. In other words, cheap power
    >>>> supplies kill motherboards, hard drives, CPUs, RAM, etc.


    >>>> Your post is about TWO poor quality power supplies. I suspect
    >>>> that the first one died ungracefully, taking the motherboard out
    >>>> with it. The second one can't even power itself, apparently.


    >>>> It's your money, but people don't seem to understand that
    >>>> often spending an extra 40 bucks or so on a GOOD power
    >>>> supply can save a complete rebuild, costing hundreds of bucks.


    >>> Actually, I'm sure the power supply he bought from the
    >>> store is perfectly fine. Don't forget about "power good"!
    >>> If the power supply doesn't see this, it will not stay on.


    >> You've got that backwards, its PROVIDED by the
    >> power supply, not observed by the power supply.


    > It works both ways.


    Nope, its an output FROM the power supply, not an input TO the power supply.

    > Yes, it is provided by the power supply, and yes, it is there to prevent
    > the motherboard from starting up before the power supply stabilizes.


    Nothing like what you originally said.

    > However, on some power supplies, if there is a power
    > surge or any other issue (which can be caused by a
    > fried component on the motherboard), "Power Good"
    > will also shut down the power supply if it malfunctions.


    Nope, again, its an output FROM the power supply and the power
    supply is supposed to drop the power good signal if something has
    gone bad power wise, mainly so the motherboard can restart after
    a glitch that has seen the power supply shut down and then start again.

    The power supply doesnt even notice a fried component
    on the motherboard unless that produces a higher than
    allowed current on one of the rails it produces.
     
    Rod Speed, Aug 28, 2006
    #23
  4. .

    Rod Speed Guest

    David Matthew Wood <> wrote
    > wrote
    >> David Matthew Wood <> wrote


    >>>> Poor quality power supplies have two very nasty habits:


    >>>> 1) They die early (that is GUARANTEED, btw), often shortly after
    >>>> leaving the factory
    >>>> 2) With no built-in component protection, they often take other
    >>>> components
    >>>> with them, when they die. In other words, cheap power supplies
    >>>> kill motherboards, hard drives, CPUs, RAM, etc.


    >>>> Your post is about TWO poor quality power supplies. I suspect
    >>>> that the first one died ungracefully, taking the motherboard out
    >>>> with it. The second one can't even power itself, apparently.


    >>>> It's your money, but people don't seem to understand that
    >>>> often spending an extra 40 bucks or so on a GOOD power
    >>>> supply can save a complete rebuild, costing hundreds of bucks.


    >>> Actually, I'm sure the power supply he bought from the store is
    >>> perfectly fine. Don't forget about "power good"! If the power
    >>> supply doesn't see this, it will not stay on. That is how all ATX
    >>> power supplies are designed, and it is indeed built-in component
    >>> protection. If anything is shorting out (as could very well be the
    >>> case here, since his first power supply fried something), it will
    >>> shut down a working power supply.


    >> Good link on the Power Good Signal
    >> http://www.pcguide.com/ref/power/sup/funcPowerGood-c.html
    >> and how "Some extremely el-cheapo power supplies may "fake"
    >> the Power Good signal by just tying it to another +5 V line."


    > Yes, and while it doesn't directly have anything to do with Power
    > Good, such power supplies don't provide any protection either.


    You dont know that on that ANY claim.

    > If you try to fire up a GOOD supply and it doesn't observe the correct
    > loads (either from not being properly connected or from something that
    > is shorting), it will shut down in order to prevent damage


    Yes. But that is true even with cheap power supplys too.

    Where they mostly fail is shutting down properly when the power supply fails.

    > since it is bad for a power supply to run without a load.


    Oh bullshit.

    > Same goes with amps.


    Nope, completely different.

    > If you power up an amp and crank the volume without speakers attached,
    > it will either a, go into thermal shut down, or b, self-destruct.


    Utterly mangled all over again.
     
    Rod Speed, Aug 28, 2006
    #24
  5. .

    DaveW Guest

    When you use a "cheap" power supply unit ($35 for PSU & case) you run into
    the problem that if the PSU fails it usually burns out the motherboard too.
    High end PSU's usually do NOT do that; they include built in protection
    circuits.

    --
    DaveW

    ----------------
    "." <> wrote in message
    news:...
    > Yesterday morning, ten hours after I'd last powered my PC down, I turned
    > it on and noticed immediately a burning "electrical fire" smell.
    >
    > Turned the computer off (using Windows shutdown first from the login
    > screen), disconnected all peripherals and the power, opened the case.
    > Attached the power cord only, started it, everything worked (hard drives
    > were cycling, CPU fan going, motherboard lights on, etc.), but I noticed
    > the smell again. I did some sniffing and it was definitely coming from
    > the power supply. Then the computer just stopped.
    >
    > I am not a "hardware guy" but I did some research on the web, consulted
    > with the friend who helped me build the computer, and it seemed pretty
    > open and shut. The 350 watt supply that came with the case ($35 for
    > case and supply) was to blame.
    >
    > So went to CompUSA today and picked up
    > http://www.compusa.com/products/product_info.asp?product_code=283768 -
    > seemed to be a worthy "bang for the buck" 400-watt supply.
    >
    > http://www.hardwaresecrets.com/article/362/ is the instructions I
    > followed.
    >
    > Before disconnecting the old PSU, I carefully labelled every connection,
    > showing what it was connected to, and the orientation on the drive or
    > board. (The PSU had a 20-pin connection to the motherboard, the ATX12V
    > comnnector, and my computer has two hard drives, a DVD drive, and a 3.5"
    > floppy.)
    >
    > Plugged the computer in, turned on the PSU, and nothing. Ultimately, I
    > tried a known good power cord and the new cord that came with the PSU, a
    > known working outlet, several permutations, nothing. The voltage
    > selector is correct (115 volts) on the back of the PSU. When I apply
    > power, the CPU fan turns for about two seconds then stops (no harsh or
    > unusual noises - it was turning fine yesterday). The green light on the
    > motherboard stays lit. But no drive lights come on, and no sign of any
    > activity.
    >
    > I don't have a multimeter. I'm not an electrician or electrical
    > engineer. I just want some suggestions on what might be wrong and how
    > to fix it. FWIW, the motherboard seems to show no abuse; the capacitors
    > all look shiny and intact.
    >
    > My friend who built the PC for me is traveling, and I will ultimately
    > bring the computer to him and his extensive testbench if I can't figure
    > this out myself. But I'm really at my wit's end now and am hoping for a
    > few useful "try this" suggestions.
     
    DaveW, Aug 29, 2006
    #25
  6. In article <>,
    "Rod Speed" <> wrote:

    > David Matthew Wood <> wrote
    > > wrote
    > >> David Matthew Wood <> wrote

    >
    > >>>> Poor quality power supplies have two very nasty habits:

    >
    > >>>> 1) They die early (that is GUARANTEED, btw), often shortly after
    > >>>> leaving the factory
    > >>>> 2) With no built-in component protection, they often take other
    > >>>> components
    > >>>> with them, when they die. In other words, cheap power supplies
    > >>>> kill motherboards, hard drives, CPUs, RAM, etc.

    >
    > >>>> Your post is about TWO poor quality power supplies. I suspect
    > >>>> that the first one died ungracefully, taking the motherboard out
    > >>>> with it. The second one can't even power itself, apparently.

    >
    > >>>> It's your money, but people don't seem to understand that
    > >>>> often spending an extra 40 bucks or so on a GOOD power
    > >>>> supply can save a complete rebuild, costing hundreds of bucks.

    >
    > >>> Actually, I'm sure the power supply he bought from the store is
    > >>> perfectly fine. Don't forget about "power good"! If the power
    > >>> supply doesn't see this, it will not stay on. That is how all ATX
    > >>> power supplies are designed, and it is indeed built-in component
    > >>> protection. If anything is shorting out (as could very well be the
    > >>> case here, since his first power supply fried something), it will
    > >>> shut down a working power supply.

    >
    > >> Good link on the Power Good Signal
    > >> http://www.pcguide.com/ref/power/sup/funcPowerGood-c.html
    > >> and how "Some extremely el-cheapo power supplies may "fake"
    > >> the Power Good signal by just tying it to another +5 V line."

    >
    > > Yes, and while it doesn't directly have anything to do with Power
    > > Good, such power supplies don't provide any protection either.

    >
    > You dont know that on that ANY claim.


    What, that cheap POS power supplies don't shut down right away if
    something is shorting? Well lets see. I have some sitting around that
    will not power up at all because something in the machine shorted them
    out. I have others sitting around that still power up and work just
    fine after being shorted out, because they shut down right away before
    damage was done.

    >
    > > If you try to fire up a GOOD supply and it doesn't observe the correct
    > > loads (either from not being properly connected or from something that
    > > is shorting), it will shut down in order to prevent damage

    >
    > Yes. But that is true even with cheap power supplys too.
    >
    > Where they mostly fail is shutting down properly when the power supply fails.


    Shutting down before damage is done you mean. I've witnessed both.

    A, something will short out and PS will smoke.
    or
    B, something will short out and PS will turn off. In which case, after
    dealing with whatever caused the short, the power supply will come to
    life and work just fine.

    >
    > > since it is bad for a power supply to run without a load.

    >
    > Oh bullshit.


    Oh really? Why don't you try it then. Force a cheap power supply on
    and let it run for a while without a load. See what happens.

    >
    > > Same goes with amps.

    >
    > Nope, completely different.
    >
    > > If you power up an amp and crank the volume without speakers attached,
    > > it will either a, go into thermal shut down, or b, self-destruct.

    >
    > Utterly mangled all over again.


    Again...oh really? Take a high current amplifier, give it an audio
    feed, disconnect anything that will create a load on the outputs, crank
    the levels, and see what happens.
     
    David Matthew Wood, Aug 29, 2006
    #26
  7. In article <>,
    "Rod Speed" <> wrote:

    > David Matthew Wood <> wrote
    > > Rod Speed <> wrote
    > >> David Matthew Wood <> wrote

    >
    > >>>> Poor quality power supplies have two very nasty habits:

    >
    > >>>> 1) They die early (that is GUARANTEED, btw),
    > >>>> often shortly after leaving the factory
    > >>>> 2) With no built-in component protection, they often take other
    > >>>> components with them, when they die. In other words, cheap power
    > >>>> supplies kill motherboards, hard drives, CPUs, RAM, etc.

    >
    > >>>> Your post is about TWO poor quality power supplies. I suspect
    > >>>> that the first one died ungracefully, taking the motherboard out
    > >>>> with it. The second one can't even power itself, apparently.

    >
    > >>>> It's your money, but people don't seem to understand that
    > >>>> often spending an extra 40 bucks or so on a GOOD power
    > >>>> supply can save a complete rebuild, costing hundreds of bucks.

    >
    > >>> Actually, I'm sure the power supply he bought from the
    > >>> store is perfectly fine. Don't forget about "power good"!
    > >>> If the power supply doesn't see this, it will not stay on.

    >
    > >> You've got that backwards, its PROVIDED by the
    > >> power supply, not observed by the power supply.

    >
    > > It works both ways.

    >
    > Nope, its an output FROM the power supply, not an input TO the power supply.


    It doesn't matter. Some supplies monitor that load. I have quite a few
    that will shut down if load on PG does not exist.

    >
    > > Yes, it is provided by the power supply, and yes, it is there to prevent
    > > the motherboard from starting up before the power supply stabilizes.

    >
    > Nothing like what you originally said.


    No, I'm half agreeing with you about what power good is there for.

    >
    > > However, on some power supplies, if there is a power
    > > surge or any other issue (which can be caused by a
    > > fried component on the motherboard), "Power Good"
    > > will also shut down the power supply if it malfunctions.

    >
    > Nope, again, its an output FROM the power supply and the power
    > supply is supposed to drop the power good signal if something has
    > gone bad power wise, mainly so the motherboard can restart after
    > a glitch that has seen the power supply shut down and then start again.


    And some supplies shut down completely. I have a few sitting right here
    that will do that.

    >
    > The power supply doesnt even notice a fried component
    > on the motherboard unless that produces a higher than
    > allowed current on one of the rails it produces.


    And now we go back to the original post where the OP said that his new
    power supply would not stay on - not because it was bad, but because
    there was an issue with something it was powering up. As it turned out,
    once he cleared up that issue, all was well.
     
    David Matthew Wood, Aug 29, 2006
    #27
  8. .

    Rod Speed Guest

    David Matthew Wood <> wrote
    > Rod Speed <> wrote
    >> David Matthew Wood <> wrote
    >>> wrote
    >>>> David Matthew Wood <> wrote


    >>>>>> Poor quality power supplies have two very nasty habits:


    >>>>>> 1) They die early (that is GUARANTEED, btw), often shortly after
    >>>>>> leaving the factory
    >>>>>> 2) With no built-in component protection, they often take other
    >>>>>> components with them, when they die. In other words, cheap
    >>>>>> power supplies kill motherboards, hard drives, CPUs, RAM, etc.


    >>>>>> Your post is about TWO poor quality power supplies. I suspect
    >>>>>> that the first one died ungracefully, taking the motherboard out
    >>>>>> with it. The second one can't even power itself, apparently.


    >>>>>> It's your money, but people don't seem to understand that
    >>>>>> often spending an extra 40 bucks or so on a GOOD power
    >>>>>> supply can save a complete rebuild, costing hundreds of bucks.


    >>>>> Actually, I'm sure the power supply he bought from the store is
    >>>>> perfectly fine. Don't forget about "power good"! If the power
    >>>>> supply doesn't see this, it will not stay on. That is how all ATX
    >>>>> power supplies are designed, and it is indeed built-in component
    >>>>> protection. If anything is shorting out (as could very well be the
    >>>>> case here, since his first power supply fried something), it will
    >>>>> shut down a working power supply.


    >>>> Good link on the Power Good Signal
    >>>> http://www.pcguide.com/ref/power/sup/funcPowerGood-c.html
    >>>> and how "Some extremely el-cheapo power supplies may "fake"
    >>>> the Power Good signal by just tying it to another +5 V line."


    >>> Yes, and while it doesn't directly have anything to do with Power
    >>> Good, such power supplies don't provide any protection either.


    >> You dont know that on that ANY claim.


    > What, that cheap POS power supplies don't
    > shut down right away if something is shorting?


    Nope, that they dont have ANY protection.

    > Well lets see. I have some sitting around that will not power
    > up at all because something in the machine shorted them out.


    You dont know that that is the reason why they died.

    > I have others sitting around that still power up and
    > work just fine after being shorted out, because they
    > shut down right away before damage was done.


    Plenty of cheap power supplys do that fine.

    >>> If you try to fire up a GOOD supply and it doesn't observe the
    >>> correct loads (either from not being properly connected or from
    >>> something that is shorting), it will shut down in order to prevent damage


    >> Yes. But that is true even with cheap power supplys too.


    >> Where they mostly fail is shutting down
    >> properly when the power supply fails.


    > Shutting down before damage is done you mean.


    Yep.

    > I've witnessed both.


    Yes, so you claim that they dont have ANY protection is just plain wrong.

    > A, something will short out and PS will smoke.
    > or
    > B, something will short out and PS will turn off. In which
    > case, after dealing with whatever caused the short, the
    > power supply will come to life and work just fine.


    Yep, and when that last is seen with a cheap power
    supply, they must have had SOME protection.

    >>> since it is bad for a power supply to run without a load.


    >> Oh bullshit.


    > Oh really? Why don't you try it then.


    Done that plenty of times thanks.

    > Force a cheap power supply on and let it run
    > for a while without a load. See what happens.


    Nothing, thats what. It works fine when its used with a load.

    >>> Same goes with amps.


    >> Nope, completely different.


    >>> If you power up an amp and crank the volume without speakers
    >>> attached, it will either a, go into thermal shut down, or b, self-destruct.


    >> Utterly mangled all over again.


    > Again...oh really?


    Fraid so.

    > Take a high current amplifier, give it an audio feed,
    > disconnect anything that will create a load on the
    > outputs, crank the levels, and see what happens.


    Nothing special with a properly designed amp.

    Because it isnt hard to accidentially disconnect a speaker.
     
    Rod Speed, Aug 29, 2006
    #28
  9. .

    Rod Speed Guest

    David Matthew Wood <> wrote
    > Rod Speed <> wrote
    >> David Matthew Wood <> wrote
    >>> Rod Speed <> wrote
    >>>> David Matthew Wood <> wrote


    >>>>>> Poor quality power supplies have two very nasty habits:


    >>>>>> 1) They die early (that is GUARANTEED, btw),
    >>>>>> often shortly after leaving the factory
    >>>>>> 2) With no built-in component protection, they often take other
    >>>>>> components with them, when they die. In other words, cheap power
    >>>>>> supplies kill motherboards, hard drives, CPUs, RAM, etc.


    >>>>>> Your post is about TWO poor quality power supplies. I suspect
    >>>>>> that the first one died ungracefully, taking the motherboard out
    >>>>>> with it. The second one can't even power itself, apparently.


    >>>>>> It's your money, but people don't seem to understand that
    >>>>>> often spending an extra 40 bucks or so on a GOOD power
    >>>>>> supply can save a complete rebuild, costing hundreds of bucks.


    >>>>> Actually, I'm sure the power supply he bought from the
    >>>>> store is perfectly fine. Don't forget about "power good"!
    >>>>> If the power supply doesn't see this, it will not stay on.


    >>>> You've got that backwards, its PROVIDED by the
    >>>> power supply, not observed by the power supply.


    >>> It works both ways.


    >> Nope, its an output FROM the power supply, not an input TO the power supply.


    > It doesn't matter.


    Corse it does.

    > Some supplies monitor that load.


    The power good line isnt even a load.

    > I have quite a few that will shut down if load on PG does not exist.


    Fantasy. There are quite a few that will shut down if the
    OUTPUT RAILS arent loaded, a different matter entirely.

    >>> Yes, it is provided by the power supply, and yes,
    >>> it is there to prevent the motherboard from starting
    >>> up before the power supply stabilizes.


    >> Nothing like what you originally said.


    > No, I'm half agreeing with you about what power good is there for.


    No you arent, you just said that some power
    supplys monitor if that line is loaded. No they dont.

    >>> However, on some power supplies, if there is a power
    >>> surge or any other issue (which can be caused by a
    >>> fried component on the motherboard), "Power Good"
    >>> will also shut down the power supply if it malfunctions.


    >> Nope, again, its an output FROM the power supply and the power
    >> supply is supposed to drop the power good signal if something has
    >> gone bad power wise, mainly so the motherboard can restart after
    >> a glitch that has seen the power supply shut down and then start again.


    > And some supplies shut down completely.


    Different matter entirely.

    Yes, some do need to be unplugged from the mains to reset themselves.

    > I have a few sitting right here that will do that.


    >> The power supply doesnt even notice a fried component
    >> on the motherboard unless that produces a higher than
    >> allowed current on one of the rails it produces.


    > And now we go back to the original post where the OP said that his
    > new power supply would not stay on - not because it was bad, but
    > because there was an issue with something it was powering up.


    Yes, but that had nothing to do with the power good line.

    > As it turned out, once he cleared up that issue, all was well.


    Yes, but thats irrelevant to YOUR claims about the power good line.
     
    Rod Speed, Aug 29, 2006
    #29
  10. In article <>,
    "Rod Speed" <> wrote:

    > > Well lets see. I have some sitting around that will not power
    > > up at all because something in the machine shorted them out.

    >
    > You dont know that that is the reason why they died.


    And do you know this exactly? I've seen it happen firsthand.

    >
    > > I have others sitting around that still power up and
    > > work just fine after being shorted out, because they
    > > shut down right away before damage was done.

    >
    > Plenty of cheap power supplys do that fine.


    Maybe, but not as likely as it would be if it weren't a power supply
    where corners were cut in making it.

    > >>> If you try to fire up a GOOD supply and it doesn't observe the
    > >>> correct loads (either from not being properly connected or from
    > >>> something that is shorting), it will shut down in order to prevent damage

    >
    > >> Yes. But that is true even with cheap power supplys too.

    >
    > >> Where they mostly fail is shutting down
    > >> properly when the power supply fails.

    >
    > > Shutting down before damage is done you mean.

    >
    > Yep.
    >
    > > I've witnessed both.

    >
    > Yes, so you claim that they dont have ANY protection is just plain wrong.


    I was replying to an article that mentioned how some skimp on PG and
    just supply a normal 5v lead instead. If a power supply is built like
    that, then it's very likely corners were cut in other areas too,
    including the protection circuitry.

    > >>> since it is bad for a power supply to run without a load.

    >
    > >> Oh bullshit.

    >
    > > Oh really? Why don't you try it then.

    >
    > Done that plenty of times thanks.


    Consider yourself lucky then.

    > >>> Same goes with amps.

    >
    > >> Nope, completely different.

    >
    > >>> If you power up an amp and crank the volume without speakers
    > >>> attached, it will either a, go into thermal shut down, or b,
    > >>> self-destruct.

    >
    > >> Utterly mangled all over again.

    >
    > > Again...oh really?

    >
    > Fraid so.
    >
    > > Take a high current amplifier, give it an audio feed,
    > > disconnect anything that will create a load on the
    > > outputs, crank the levels, and see what happens.

    >
    > Nothing special with a properly designed amp.


    All amps come with manuals that say to NEVER operate them without a
    proper load. There are reasons for this.

    >
    > Because it isnt hard to accidentially disconnect a speaker.


    Again, consider yourself lucky. Either you weren't running much power
    through this thing, or you caught it in a short time - or you weren't
    running the amp much beyond 20% of its capacity with a constant signal
    running through it.
     
    David Matthew Wood, Aug 29, 2006
    #30
  11. .

    Rod Speed Guest

    David Matthew Wood <> wrote
    > Rod Speed <> wrote
    >> David Matthew Wood <> wrote


    >>> Well lets see. I have some sitting around that will not power
    >>> up at all because something in the machine shorted them out.


    >> You dont know that that is the reason why they died.


    > And do you know this exactly?


    I know that you cant be sure why they have failed.

    > I've seen it happen firsthand.


    Or assumed that they got killed by the machine shorting them out
    when they may have died and killed what is powered from them.
    That last isnt that uncommon with cheap power supplys.

    >>> I have others sitting around that still power up and
    >>> work just fine after being shorted out, because they
    >>> shut down right away before damage was done.


    >> Plenty of cheap power supplys do that fine.


    > Maybe,


    No maybe about it.

    > but not as likely as it would be if it weren't a power
    > supply where corners were cut in making it.


    Wrong, there arent many so badly designed that they
    dont shut down when one of the rails is shorted.

    Plenty more fail and kill what is powered by the power supply.

    >>>>> If you try to fire up a GOOD supply and it doesn't observe the
    >>>>> correct loads (either from not being properly connected or from
    >>>>> something that is shorting), it will shut down in order to
    >>>>> prevent damage


    >>>> Yes. But that is true even with cheap power supplys too.


    >>>> Where they mostly fail is shutting down
    >>>> properly when the power supply fails.


    >>> Shutting down before damage is done you mean.


    >> Yep.


    >>> I've witnessed both.


    >> Yes, so your claim that they dont have ANY protection is just plain wrong.


    > I was replying to an article that mentioned how some
    > skimp on PG and just supply a normal 5v lead instead.


    Yes, but that isnt necessarily the end of the world
    if the design ensures that that comes up last.

    > If a power supply is built like that, then it's very likely corners
    > were cut in other areas too, including the protection circuitry.


    Not necessarily if the supply ensures that that 5V rail comes up last.

    And you claimed that they dont have ANY protection. Even
    the cheapest power supply have SOME protection even if
    they dont necessarily adequately protect against the power
    supply over voltaging some of the rails as it dies.

    Essentially because that sort of independant protection against
    any output rail going out of spec costs more to provide.

    >>>>> since it is bad for a power supply to run without a load.


    >>>> Oh bullshit.


    >>> Oh really? Why don't you try it then.


    >> Done that plenty of times thanks.


    > Consider yourself lucky then.


    Nope, I know that wont kill a power supply.

    >>>>> Same goes with amps.


    >>>> Nope, completely different.


    >>>>> If you power up an amp and crank the volume without speakers
    >>>>> attached, it will either a, go into thermal shut down, or b,
    >>>>> self-destruct.


    >>>> Utterly mangled all over again.


    >>> Again...oh really?


    >> Fraid so.


    >>> Take a high current amplifier, give it an audio feed,
    >>> disconnect anything that will create a load on the
    >>> outputs, crank the levels, and see what happens.


    >> Nothing special with a properly designed amp.


    > All amps come with manuals that say to NEVER operate
    > them without a proper load. There are reasons for this.


    Doesnt mean they will be killed by the accidental disconnection of a speaker.

    >> Because it isnt hard to accidentially disconnect a speaker.


    > Again, consider yourself lucky.


    No thanks, I know that wont kill a properly designed amp.

    > Either you weren't running much power through this thing,
    > or you caught it in a short time - or you weren't running the
    > amp much beyond 20% of its capacity with a constant signal
    > running through it.


    Easy to claim. I manage to fry the speakers
    by over driving them and the amp was fine.
     
    Rod Speed, Aug 29, 2006
    #31
  12. In article <>,
    "Rod Speed" <> wrote:

    > David Matthew Wood <> wrote
    > > Rod Speed <> wrote
    > >> David Matthew Wood <> wrote

    >
    > >>> Well lets see. I have some sitting around that will not power
    > >>> up at all because something in the machine shorted them out.

    >
    > >> You dont know that that is the reason why they died.

    >
    > > And do you know this exactly?

    >
    > I know that you cant be sure why they have failed.
    >
    > > I've seen it happen firsthand.

    >
    > Or assumed that they got killed by the machine shorting them out
    > when they may have died and killed what is powered from them.
    > That last isnt that uncommon with cheap power supplys.


    Um.... no. Many years ago, I overestimated the space between the bottom
    of a hard drive and the metal frame of the case. Turned machine on,
    drive control board shorted and smoked. Because of this short, power
    supply also smoked. How is that an assumption exactly?
    And again later, I unknowingly had a bad power connector which turned
    out to be shorted. Fired up the supply, it came on for not even half a
    second, and turned itself off again. Short was cleared, power was fired
    up again, and all was well.

    >
    > >>> I have others sitting around that still power up and
    > >>> work just fine after being shorted out, because they
    > >>> shut down right away before damage was done.

    >
    > >> Plenty of cheap power supplys do that fine.

    >
    > > Maybe,

    >
    > No maybe about it.


    Plenty maybe about it, it all depends on design.

    >
    > > but not as likely as it would be if it weren't a power
    > > supply where corners were cut in making it.

    >
    > Wrong, there arent many so badly designed that they
    > dont shut down when one of the rails is shorted.


    I had one smoke due to this.

    >
    > Plenty more fail and kill what is powered by the power supply.


    Yes, and the better designed supplies shut down before this happens -
    just as the better designs shut off in time to save themselves if they
    are shorted.

    > > I was replying to an article that mentioned how some
    > > skimp on PG and just supply a normal 5v lead instead.

    >
    > Yes, but that isnt necessarily the end of the world
    > if the design ensures that that comes up last.
    >
    > > If a power supply is built like that, then it's very likely corners
    > > were cut in other areas too, including the protection circuitry.

    >
    > Not necessarily if the supply ensures that that 5V rail comes up last.


    And not all of them do.

    > And you claimed that they dont have ANY protection. Even
    > the cheapest power supply have SOME protection even if
    > they dont necessarily adequately protect against the power
    > supply over voltaging some of the rails as it dies.


    -sigh- protection as in protecting the power supply itself, which is
    what I meant. In other words, its ability to shut itself down BEFORE
    damage is done to the supply, which was the original case of this
    thread. The OP's power supply died. He went to the store and bought
    another one, and put it in his machine. He went to fire it up, it shut
    down right afterwards. The OP then corrected a wiring problem, fired it
    up again without changing any components, and all was good.
    If I had wanted to go any further than that, I could have just said that
    the fuse in your mains fuse box IS the protection - not against
    equipment, but against fire... but perhaps I should have stated this
    anyway.

    >
    > Essentially because that sort of independant protection against
    > any output rail going out of spec costs more to provide.


    yes..

    >
    > >>>>> since it is bad for a power supply to run without a load.

    >
    > >>>> Oh bullshit.

    >
    > >>> Oh really? Why don't you try it then.

    >
    > >> Done that plenty of times thanks.

    >
    > > Consider yourself lucky then.

    >
    > Nope, I know that wont kill a power supply.


    Then why do the manufacturers of these very supplies advise against this?
    >
    > >>>>> Same goes with amps.

    >
    > >>>> Nope, completely different.

    >
    > >>>>> If you power up an amp and crank the volume without speakers
    > >>>>> attached, it will either a, go into thermal shut down, or b,
    > >>>>> self-destruct.

    >
    > >>>> Utterly mangled all over again.

    >
    > >>> Again...oh really?

    >
    > >> Fraid so.

    >
    > >>> Take a high current amplifier, give it an audio feed,
    > >>> disconnect anything that will create a load on the
    > >>> outputs, crank the levels, and see what happens.

    >
    > >> Nothing special with a properly designed amp.

    >
    > > All amps come with manuals that say to NEVER operate
    > > them without a proper load. There are reasons for this.

    >
    > Doesnt mean they will be killed by the accidental disconnection of a speaker.


    Accidental disconnection of a speaker, which is usually caught shortly
    afterwards since you're now not hearing sound out of this speaker. If
    this condition were allowed to continue and you ran the amp at constant
    high power, it will eventually kill the amp - if it doesn't trip the
    protection circuits first!

    > >> Because it isnt hard to accidentially disconnect a speaker.

    >
    > > Again, consider yourself lucky.

    >
    > No thanks, I know that wont kill a properly designed amp.


    Well since you seem to know more than the people who made these amps,
    all of whom say NEVER run an amp without a load...

    >
    > > Either you weren't running much power through this thing,
    > > or you caught it in a short time - or you weren't running the
    > > amp much beyond 20% of its capacity with a constant signal
    > > running through it.

    >
    > Easy to claim. I manage to fry the speakers
    > by over driving them and the amp was fine.


    And while these speakers are being over driven, you are still driving
    them and thus the amp is seeing a load! How long after completely
    melting the speaker coils, have you run this amp exactly? How long have
    you let it run under constant high power without a load? Do you
    actually test this by turning the volume up higher and higher AFTER you
    manage to blow the speakers?
     
    David Matthew Wood, Aug 29, 2006
    #32

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Paminifarm

    Fried Another Power Supply Box

    Paminifarm, Nov 24, 2004, in forum: Computer Support
    Replies:
    4
    Views:
    881
    Duck ducking
    Nov 25, 2004
  2. that one

    won't power on: power supply or motherboard?

    that one, Apr 19, 2005, in forum: Computer Support
    Replies:
    8
    Views:
    7,882
    Blinky the Shark
    Apr 21, 2005
  3. jeff
    Replies:
    1
    Views:
    1,181
  4. Replies:
    2
    Views:
    760
  5. nick
    Replies:
    0
    Views:
    1,874
  6. Mark

    Fried a Power Supply

    Mark, Oct 16, 2003, in forum: Computer Information
    Replies:
    17
    Views:
    1,987
  7. mr x
    Replies:
    4
    Views:
    669
  8. udz2002

    Replaced power supply now computer won't boot

    udz2002, Sep 23, 2010, in forum: Computer Support
    Replies:
    38
    Views:
    8,678
    Patrick
    Sep 27, 2010
Loading...