Motherboard fuses - missing?

Mobos often have empty spaces where it looks like something could go. Not every model uses every space. RTFM:

I have RTFM, but TFM doesn't mention the fuse, and I doubt that these missing fuses are for any missing functions. I've also never heard of TFM ever going into this much detail about the hardware.

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

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

It's easier to make one board design that's a jack of all trades, then later modify it only the (least) amount necessary to meet some requirement or cut cost or (whatever the scenario). Did you determine how the (typically fused) ports are getting power since those fuse positions are unfilled?

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.

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

Fuck sake...you really have no idea do you?

It is far cheaper for manufacturers to design and stock one PCB to work across many models than to design and make a PCB for each individual model.

For that particular model.

That makes sense.

This is the first time I've seen a mobo made for fuses where the left-out fuses weren't substituted with jumper wires (PC Chips, some ECS) or copper traces between each fuse location's solder pads.

Yes, BUT for that particular model the fuses ARE missing. Our presumptions about why they might have the fuse spots still doesn't address his original query.

Hi...

Just thinking out loud... not only different models, but that one board design will have been designed for use in different parts of the world.

Perhaps outher countries have different code requirements for things "extended from" the main chassis?

Wouldn't explain a missing fuse all by itself, but perhaps one jumper is eliminated elsewhere and then the fuse is required...

Just a thought.

Ken

It's an interesting thought but the remaining question is still, if the fuse isn't installed _and_ the fuse location isn't jumpered, why and where did they reroute the power for the ports? "Usually" when a fuse is (or isn't) used, the power is still delivered on same traces either way, the circuit change is prior to that point.

"larry moe 'n curly" wrote in news: snipped-for-privacy@g47g2000cwa.googlegroups.com:

....

I can't tell you why, or how. But a suggestion might help.

I've been doing PC Repair for a long time. And I've often seen the same mobo design used by different manufacturers. And in the same manufacturer, I've seen boards that are the same layout, but different in the number of components, the one with less components on the board being the cheaper version.

What I would try to do is find other boards on the manufacturers website with the same layout. Often they include a picture of the board (not always the best rez) that might show you what you're looking for.

I've often seen boards that are the same layout from Chaintech, PC Chips, Asus, Epox and others. It's a pain in the tukas, but you might also be able to find a board with the same layout but different features with one of these other vendors.

The boards will always be the same size physically, and have the same locations of the CPU socket and primary chipset(s). But they may have a different number of bus interfaces, or memory sockets. And often they have different bioses. However, I have (in the past) been able to use one vendor's drivers to make a piece of hardware work.

Hope that helps lmac. :)

Curly

yak, yak, yak, oooooohh....

And?

Because its a pointless one. I could rabbit on incessantly about buffers etc but what's the point?

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.

The point is that some of us are interested in motherboard layout/design/etc... it is a hardware group.

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 this case, maybe a certain country has different safety standards that require the keyboard, mouse, etc. to be fused, so on the models sent to that country they are fused, and the same model marketed in other countries leaves the fuse out and maybe puts a cheaper jumper in to save money on components. In large quantities the fuse may cost a penny and a jumper may cost 1/10 of a penny. Over hundreds of thousands of boards it makes a difference.

While I'm sure that on this MOBO the fuse POSITIONS are open, I'd bet that the circuit is not. Chances are that SOMEWHERE ELSE in the path of that circuit where the fuse would have been there is a jumper. As some other knowlegable posters stated, it may not be physically in the same location as the missing fuse, but it is in the same circuit. I'm sure if two boards were compared sie-by-side and only one is found to have fuses then I'd bet that somewhere on that board it is missing a jumper for each fuse it has. They may be the size of a surface-mount resistor and thus very difficult to find, or it may be a tiny solder bridge or even a full size jumper like the 1/4 watt size, but it must be there somewhere!