What is this trace geometry for?

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#1
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I accidentally shorted something out with a screwdriver on my car stereo head unit, and it doesn't work anymore. I think I found the damage, but I'm not sure it's a fault, as it's really tiny, and I don't understand why the traces near it are shaped as they are.

I'm guessing that the oval, labeled "F01", is a placeholder for an optional SMD. For this part to be active, a tech could just 'burn' the thin trace, like I accidentally did, to make a voltage drop across "F01" (like setting a fuse bit - a real one).

Does this sound right? I'll just blob some solder on "F01", if so...

On the other hand, the "open circuit" may be part of the design - another placeholder for an optional part - and I need to keep looking...

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I think F01 is a dual-circuit fuse. The void suggests one is "blown".

Perhaps this form of fuse is required by safety regulations to preclude sustained high current flow and fire.

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I'd agree. Looks like there's been some soldering around the amp chip also.

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I think perhaps its so the tech can repair the board with a busted track fuse.

For instance if the board fails during testing after assembly and the fuse goes, a simple drop of solder and the other fuse is brought into action. Better then scrapping the board.

oddbudman

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Fuse traces - sounds like a good idea! They could have saved a board or two of mine, though I doubt my ability to etch that fine...

"F01" has been bridged, and I'll let you know how it works in a while (roommate stole the car). Thanks :)

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It works perfectly. :)

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wow, I love tech.