i got the rmr-d100 to use as a spdif interface (for my sony pcm-m1 dat). i've stopped using it more or less - since a simple cable from core audio works really well (easy to carry too). really, i only tend to archive my dat recordings to disk - had i known the cable would have done the job, i might have just stuck with the $40 cable. it's a much cheaper option. *however* the rmr-d100 does properly convert the 3.3 volts supplied by the dat, to the full 5 volt spdif standard, and it's two-way as well if you need that. (though, there are two-way cables).
anyway, i was a little surprised when one day the rmr-d100 just didn't work, wouldn't turn on (of course just when needed it, this was before i got the cable). anyway, like everything else i own, i decided to take it apart and take a look inside.
at first, i really wasn't sure what i was looking for. i didn't see a fuse at all. so i was a bit stumped, and kept staring at the board, looking around where the power came in and at that switches too (sometimes external switches housing get dislodged, you can test that by manually moving them on the board).
finally i noticed the fuse, it looked more like a capacitor - and soldered right onto the board. it's not replaceable. a bit stumped again, it occurred to me how to test a blown fuse. just bridge the leads on the main board with a plain wire. that's more or less what a fuse is, just that it *breaks* when overloaded by current.
so with the wire in place, the unit powered right up. but the fuse was soldered to the board, not as simple to replace as tossing in another fuse. solution: just wire up another fuse in parallel, using the existing contact points on the board.
darren was in town at the time and convinced me to make it more elegant than just hardwiring another internal fuse (which would have been be fine). so we went to norvac electronics, and got a fuse receptacle. found a place in the housing with enough room, and drilled a hole for the housing. wired up the leads to the board. and voila, an externally accessible, and replaceable fuse.
so next time this happens... i won't have to take the thing apart. looks nice too.
i'm assuming manufacturers save a few pennies on this by making it easier to assemble, probably totally automated. an external fuse would require more delicate assembly i guess, perhaps with manual labor. the down side again, i'm sure some of these are just tossed out when they die - when it's really just a blown fuse.