Maybe I should have been more clear in my last post. All of the fuses I measured had very close to zero resistance. I always zero out my Fluke 88 meter before I take measurements which accounts for the resistance in my leads so I get actual measurements.
When I say fuse R4 is somehow shorted to ground what I mean is that nothing on the 3.3 volt circuit is working. (R4 is for 3.3 volts). The fuse is still good, it measures zero resistance. If I measure between one of the fuse contacts and the black connector pin for the ground wire or any ground point on the circuit board there is zero resistance. That means the 3.3 volt supply is shorted to ground. That’s why nothing on the 3.3 volt supply is working. In fact, nothing really works because as soon as you plug the board up, it lights all four LED’s for one second and then shuts down everything. Another indicator that all 4 fuses work, (4 LED’s).
The additional clue I have to work with is that even though the 3.3 volt supply is shorted to ground, the fuse hasn’t blew. If it were grounded AFTER the fuse, you would think the fuse would have blown. The circuit power would have come from the supply, to the fuse, to the ground, therefore fuse blows. If the ground issue came before the fuse, you would think there would be a possibility that the fuse may not blow. The circuit power would come from the power supply directly to the ground before getting to the fuse and therefore no fuse to blow. This makes me think there is likely to be an issue between the layers of the multi-layer board or something bridged between the traces, (which I doubt since I can’t see anything).
When I said I couldn’t find anything else so I started measuring resisters, what I meant was I measured some of the surface mount resisters such as R7, R6, R5, R8, R48, R52, and R49. There wasn’t any method to my choice, only that they were in that particular area. They all were in specifications, so nothing really found.
