while the xbox was on, the fan shorted, but after I fixed that short, the motherboard is still shorted somewhere (from testing continuity from 5v to ground).
Ive checked for solder splashes and stuff, and I can't find the source of the short, but my ohm meter says its shorted, and the PSU just makes a buzzing noise when I try to power it on.
I think that when the fan shorted it may have damaged the the fan's power regulator (or chip, or whatever controls the fan speed), and shorted it out. (but oddly only 5v is shorted, not 12v or 3.3)
Anybody know where this is located, so I can remove it? (and replace it from a broken 1.0)
Thanks. The worlds only battery powered Xbox is nothing without a working mobo!!
Full Version: Fan Power Regulator On 1.4
anybody???
OK, i think its something other than the fan.
i took a broken mobo, shorted out the fan pins, and it still powered on. my jumper got hot, but it didn't prevent the board from turning on. Also, unlike my 1.4, after removing the short, the board returned to normal.
On my 1.4, I also noticed a solder splash shorting the capacitors C3G5 and C3G6, which I believe go between +5v and ground. After removing this solder splash, and also the caps, the 5v is still shorted to ground somewhere.
I also recreated the solder splash with my broken motherboard, and it did fail to power on (same buzzing from PSU), but again, unlike the 1.4, the problem went away as soon as I removed the short.
So, I believe the problem is somewhere else. I have checked and double checked the board, and there are no more solder splashes or visible shorts. I also wiggled all of the large capacitors with a ohmmeter on the +5v and ground to see if it was one of those that is shorted.
i took a broken mobo, shorted out the fan pins, and it still powered on. my jumper got hot, but it didn't prevent the board from turning on. Also, unlike my 1.4, after removing the short, the board returned to normal.
On my 1.4, I also noticed a solder splash shorting the capacitors C3G5 and C3G6, which I believe go between +5v and ground. After removing this solder splash, and also the caps, the 5v is still shorted to ground somewhere.
I also recreated the solder splash with my broken motherboard, and it did fail to power on (same buzzing from PSU), but again, unlike the 1.4, the problem went away as soon as I removed the short.
So, I believe the problem is somewhere else. I have checked and double checked the board, and there are no more solder splashes or visible shorts. I also wiggled all of the large capacitors with a ohmmeter on the +5v and ground to see if it was one of those that is shorted.
Grrrr. 
I found the short, one of the big capacitors was blown.
I replaced the cap with one off a broken mobo, and the short appeared to be gone.
I powered it up, frag. Dammit! 10 seconds later, the MCPX let out a big puff of smoke.
Now it powers on, frag, then after 10 seconds, it flashes orange, and wont power off.
So much for that board, rest in peace.
I found the short, one of the big capacitors was blown.
I replaced the cap with one off a broken mobo, and the short appeared to be gone.
I powered it up, frag. Dammit! 10 seconds later, the MCPX let out a big puff of smoke.
Now it powers on, frag, then after 10 seconds, it flashes orange, and wont power off.
So much for that board, rest in peace.
nice story 
I was bored today so i removed the MCPX chip, 30 seconds with a heat gun and it pops right off...
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