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Motherboard fuses - missing?

Discussion in 'Electronic Basics' started by larry moe 'n curly, Aug 17, 2005.

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  1. kony

    kony Guest

    I'm still waiting for even one example of this theory, being
    implemented.

    you're continuing to argue for a method of implementation
    that requires more to implement. For the control of the
    solder they'd have to make change... the whole point was to
    NOT have to change the board at all, only the population of
    the surfaces.
     
  2. kony

    kony Guest

    You really, really DO need to. You claim some vague theory
    of something that is possible. Yes, if you ignore all the
    details the designers faced then it may seem possible, but
    so are other alternatives. Merely citing one thing that is
    possible is in no way a proof that this is the particular
    method used.


    Along with ego it takes a little REAL HANDS ON to know about
    specific components. Some generalized theory just isn't
    worth diddly if you have zero applicable examples. 1987
    Pinball machines? LOL. Save your pennies and buy a few
    motherboard to play with... and I mean play. Poke and
    prode, test and torture. Get some hands-on then tell us
    about the port power circuits.
     
  3. CBFalconer

    CBFalconer Guest

    I surely hope not. That would be a manufacturing nightmare.
    That's what plated thru holes are for.
     
  4. kony

    kony Guest


    He seems to be thinking of 1987 arcade game boards with
    features big enough to drive a tank through, and if he
    insists that (that) is how those old boards were made, I'll
    take his word for it... but it's a sad state when someone
    who hasn't even bothered to look at a modern motherboard
    wanst to argue about how they know what's done on it.
     
  5. SMS

    SMS Guest

    Changes to the power and ground layers are much simpler than changes to
    the signal layers. No need to change the masks for the signal layers
    when you can just not populate some components.

    It's hard to believe that building two different versions of a board is
    more economical than just putting in a jumper or a fuse. But often the
    board without the fuses has other differences. It will be made out of a
    cheaper material as well. So it's no big deal to make a minor change to
    the masks for the power or ground layer, in fact the change can be made
    manually. But there is no reason to change the signal layer masks to
    remove the pads for the fuse, or the silkscreen.
     
  6. kony

    kony Guest

    In many situations it may be true, but much, much simpler is
    to not change any of the layers.

    True, not populate components instead of changing layers.

    It cannot be concluded that "it will be made out of a
    cheaper material" based on this alone. It is possible that
    some are made of cheaper material, but likewise possible
    that they are not made of cheaper material. Whether there
    is a fuse or not is no evidence of it at all.
    This is a generalized concept, not any evidence that any (PC
    motherboards) are currently produced this way.

    In fact, the vast majority are definitely not produced this
    way. If the fuse is omitted they're jumpered, or the
    surface pads are cotinuous by having a connecting track
    between them. This is a standard practice and can be
    observed on any motherboard without a fuse. This is quite
    specifically why the whole thread exists, because if this
    method is not being used on this specific board, it is an
    exception to the rule.
     
  7. Noozer

    Noozer Guest

    <snip>

    Isn't this thread dead yet???

    Whenever possible, MB makers produce one board and then only add components
    to support the features of a specific model.

    It's cheaper to make 10,000 of one board than 2,000 of five different
    boards.

    It also means that the manufacturer can produce more with a specific feature
    if it tends to sell better and leave off features that don't add value for
    the customers.
     
  8. Jasen Betts

    Jasen Betts Guest

    sometimes they use "zero ohm" surface mount resistors,
    or possibly even surface mount fuse-resistors?

    Bye.
    Jasen
     
  9. kony

    kony Guest

    Heh, I'm arguing based more on principle now than any other
    reason. We have posters making a guess, then trying to
    conclude that (what is possible) is evidence... without any
    examples, and without consideration of any other
    possibilities.
    I agree. They're absolutely not going to rework layers even
    a tiny bit when a simple surface mount component will do.
     
  10. Ken Weitzel

    Ken Weitzel Guest

    Hi...

    Hey, your arrogance has reached a level of hilarity. Maybe
    a new reality show should be considered. "Who's in charge
    of safety certification for every country in the world"

    Then again, we know that you are; perhaps you just need
    to have your staff send out an official letter to the heads
    of UL, CSA, and all the worldwide rest informing them that
    you are in charge of how things are to be done?

    Ken
     
  11. SMS

    SMS Guest

    kony wrote:

    The low end boards reduce costs in every possible way. They may be using
    non-UL approved PC board material, and are probably omitting every
    non-essential component. They are probably stuffing the minimum number
    of bypass capacitors, using the "remove capacitors one at a time until
    the board fails, then add one back" method. This would be the type of
    board where they would change the power layer to supply +5V power
    directly to the ports, eliminating the expense of a fuse or jumper, or
    of adding a trace. There are probably traces going under the fuse, which
    would make it impossible to add a connecting trace without a board
    relayout, which is very costly.

    I worked for the 2nd largest motherboard company (at the time) and we'd
    do anything reasonable to save a couple of cents per board, including
    changes to PCB layers, if the volume was high enough.
     
  12. kony

    kony Guest


    Is that a trolling attempt or are you simply ignorant of the
    fact that there is zero need to change layers for any safety
    certification?

    I never claimed anything remotely near a disregard for any
    local certification, as any market the product is targeted
    towards will have such accomodations engineered into it, NOT
    re-engineering internal layers every time.
     
  13. kony

    kony Guest

    Yes, but that is certainly NOT always done by re-engineering
    or parts substitutions when they also had a more elaborate
    or more stringent certification necessary for other global
    regions. This is quite evident with many boards.
    No, not every... you're guessing. Even junky, lowest of the
    major low-end PCChips boards have a few SMD caps, resistors
    and such going to ports whose physical sockets weren't
    installed.

    Yes they do reduce capacitor counts or quality in "some"
    designs. This is not new, but cannot be assumed to apply in
    many cases, either... the boards themselves are the proof,
    we need not overgeneralize when there are so many concrete
    proofs of these things.
    No, absolutely not. If the upper pads on the top layer are
    those for the port/features supplied (working) on a
    particular board, they do MOST DEFINITELY NOT just go and
    rework the inner layer. How hard is this to grasp? Look at
    some boards. I don't mean to be rude about this, but you're
    overgeneralizing to the point where the resulting logic is
    in error and it's useful to see why that's the case.

    It is obvious that with the traces already in place, if
    there were to be any cost-reduction in layer rework, the
    very most they would do is bridge the two solder pads, for
    several reasons. A couple - Power traces (rather than large
    planes) should not be in inner layers when fine signal lines
    are above them (as the port data lines are). They heat up
    more and could delaminate, plus cheap boards tend to have
    only 4 layers, no ground layer between these so you would
    have the potential for noise pickup.
    You are again jumping to conclusions. We cannot assume
    "probably", and with all the hundreds (if not more)
    resistors and caps surface mounted, it is rather trivial to
    put a 0 ohm resistor across the pads. To even think about
    doing it any other way costs more than just doing it the
    same way as (ironically enough) everybody has been doing it.

    Still you are drifting along with ideas based around
    erroneous conclusions. What they do, put simply:

    The entire board is designed, period. They do not rework
    the layers. Surface mounted pads are used, populated for
    differing compliance and features. This is the way it IS
    done. Look at some boards. No, look at ALL boards. This
    is the way it is done. "IF" the board the OP observed, the
    board that started this whole thread, deviates from this, it
    is unique in this regard.

    However, we still have no evidence that these missing
    components/pads are actually supply for the implemented
    ports on that board, rather than there being another
    trace(s), on the surface layer, for power.
    Sure, if there was justification, a way to do so it could be
    done for some things. That's not evidence that this is
    what's happening to modern motherboards for port power
    traces. The motherboards themselves are evidence.
     
  14. Franc Zabkar

    Franc Zabkar Guest

    I'm in no position to dispute this, but I'm finding it very hard to
    accept. Have you actually witnessed this?
    Have you any idea why the third [open] fuse is there?


    - Franc Zabkar
     
  15. Franc Zabkar

    Franc Zabkar Guest

    The only missing feature I can think of that requires +5V power is a
    firewire port. If there is no real estate set aside for a firewire
    chip on the motherboard, perhaps it is intended as a future addition
    to the Via chipset ??? Is there an unpopulated location for a firewire
    connector?


    - Franc Zabkar
     
  16. This mobo is an Asrock (Asus) K7VTA Pro rev. 1.02. I don't know if its
    chipset supports firewire, but there don't seem to be any unused pads
    that could be used for an optional firewire connector. Also I was
    wrong about the number of fuses: There's a place for a fourth fuse, in
    front of the first PCI slot, near the SATA connectors. One pad
    measures 5V, the other is probably floating because while there's 0V
    across the pads there's also 0V between that pad and ground. Near each
    missing fuse are some missing small components, most labelled as
    resistors or capacitors, others unlabelled.

    This is my first experience with Asrock, so I don't know if the mobo is
    high quality or not, but unlike some ECS and PC Chips mobos where all
    the electrolytic capacitors are a Taiwanese brand, like OST, some of
    the caps around the CPU voltage regulator seem to be Japanese because
    they're brown and labelled "KZT", which I've read is United Chemi Con.
     
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