Motherboard fuses - missing?
 

"larry moe 'n curly" ) writes:
Tom Biasi wrote:
"larry moe 'n curly" wrote in message
ups.com...

I have an Asrock (budget Asus) K7VT4A Pro ATX motherboard with three
empty spaces where it seems that fuses would normally go.

Mobos often have empty spaces where it looks like something could go. Not
every model uses every space.
RTFM: http://www.asrock.com.tw/Drivers/Man...VT4APro_um.pdf :-)

I have RTFM, but TFM doesn't mention the fuse, and I doubt that these
missing fuses are for any missing functions.

If they are not there you probably don't need them.

Yes, but why specifically is the circuit board laid out for those
fuses?

Because it's cheaper to make one board, and then stuff it as needed,
than have to make a different board for every variant, or when a small
change is necessary.

Let's say they make 100,000 boards. They start stuffing and run out
of a specific part at the 10,000 mark. If they can't get the part that
fits, then they have to scrap the remaining 90,000 boards. But when
they have foresight, they have designed the board to take some different
parts sizes just in case.

Or, and this is common in consumer equipment, one board has some features
that the other doesn't. So long as it doesn't add too much to the board
space, it's cheaper to have one board that has all the possibilities than
multiple boards.

So the fuses that are "missing" may exist on the board in a different
form. Or they may be part of feature that isn't part of what you bought,
so you don't get it.

Meanwhile, someone else might have the same board, and have those
fuses in place while fuses in a different package elsewhere are "missing".
The traces on the board simply put both in parallel so what is available
can fit the board. Or, they have some extra feature that requires some
of the "missing" parts, so the space is filled.

Michael

kony ) writes:
On Fri, 19 Aug 2005 20:07:02 +0100, Conor
wrote:

In article , kony says...
On Thu, 18 Aug 2005 21:01:03 +0100, Conor
wrote:

In article . com,
larry moe 'n curly says...

I realize that, but in this case I can't imagine why the manufacture
would vary the design because the fuses are for keyboard (and maybe
mouse), USB, and Ethernet, and this particular mobo doesn't seem to
have any missing features for these because it does allow wake on
keyboard/mouse/USB/Ethernet.

For that particular model.


Yes, BUT for that particular model the fuses ARE missing.

And?

And, the ports DO work. It was not a matter of omitting
fuses or jumpers for features not present if these are as
described. So, you have to have an alternate way of getting
the power to those ports if it's not traveling the same path
as (practically any) motherboard out there. Perhaps if
you'd more carefully examined more boards you'd appreciate
the distinction, as larry moe 'n curly did have a valid
point and had also recognized that when the fuses aren't
employed there IS a jumper in it's place or copper track
across the pads. This particular board he has is unique in
this respect.


But has someone actually traced the board? Like I said, boards
can be laid out to permit different size parts. You do not see
jumpers across the component pads. The traces take circuitous
routes, and the parts may not be right next to the alternative
component pads.

If jumpers are needed, I suspect they'd be laid out as jumpers,
rather than expecting a machine to jam in jumpers across pads
laid out for components. And the jumper pads may not be right
next to the "missing" components.

Hence unless someone gets out an ohmmeter and traces the circuit
board, they can't be sure what's happening.

Michael

In article , Michael Black says...

But has someone actually traced the board?

I doubt it.

Not forgetting that you need to not only trace both sides at the same
time. remembering those little holes are actually links from one side
to another, but also find out whethere there are layers in the middle
too.


--
Conor

If Pac-Man affected us as kids, we'd all be running around in darkened
rooms, munching magic pills and listening to repetitive electronic
music.

On 19 Aug 2005 23:48:50 GMT,
(Michael Black) wrote:


But has someone actually traced the board? Like I said, boards
can be laid out to permit different size parts. You do not see
jumpers across the component pads. The traces take circuitous
routes, and the parts may not be right next to the alternative
component pads.

If jumpers are needed, I suspect they'd be laid out as jumpers,
rather than expecting a machine to jam in jumpers across pads
laid out for components. And the jumper pads may not be right
next to the "missing" components.

While that seems logical in a good design, what we have in
these cases is "usually" a board layout that allows for the
various fuses, but then later the fuses are not added
(shaves a couple cents cost) but rather that fuse location
has a jumper wire, or just traced over.


Hence unless someone gets out an ohmmeter and traces the circuit
board, they can't be sure what's happening.

Michael

I agree, but still it's curious that this particular board
has this setup. He and I have both noted many boards with
the fuses there OR missing where they had used more obvious
method of continuity of the 5V supply by merely bridging the
pad(s) gap where a fuse could've gone.

On Sat, 20 Aug 2005 08:36:53 +0100, Conor
wrote:

In article , Michael Black says...

But has someone actually traced the board?

I doubt it.

Not forgetting that you need to not only trace both sides at the same
time. remembering those little holes are actually links from one side
to another, but also find out whethere there are layers in the middle
too.

Usually not, the 5V power plane does not extend that far and
generally singular 5V traces are not put in middle layers
for such ports. "Maybe" they did it, but if so this is
first time I (or apparently LM&C) has seen it.