Question Ashida Wii 3.3V short on my 3rd trimmed motherboard

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There is very obviously something I am missing or doing wrong. Please help me figure out what. I made a similar post after my second trimmed Wii with a 3.3 short and couldn't find an answer then. This board I trimmed extra wide in case I was trimming through something but it's happened again.

I have the pms-2 so I haven't moved the U10. Does that have to be connected to check the 3.3V line? I did try moving the U10 on one of the boards and it didn't work but there could be another issue with it.

Here are pictures of all of the trims I've done:

3rd Wii:
tempImageXq74RK.pngtempImageRewhNh.png

2nd Wii:
tempImageyYEm3l.pngtempImageuJ7u7N.png

1st Wii:
tempImagei6BsH1.pngtempImage1CyJ0O.png
 

Stitches

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I see nothing visually obvious. No errant solder blobs, no puddles of burnt flux, no cut through components.....it's strange that you have the same problem with every trim. I'm having trouble finding potential causes for a repeatable 3.3v short to ground that isn't physical damage
 
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I see nothing visually obvious. No errant solder blobs, no puddles of burnt flux, no cut through components.....it's strange that you have the same problem with every trim. I'm having trouble finding potential causes for a repeatable 3.3v short to ground that isn't physical damage
It's so strange! And getting increasingly frustrating. Does the U10 not being moved have anything to do with it potentially?
 
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Would it be worth it to upload pictures of the sanded sides?

Are there common issues in the cutting process that can cause this to happen?
 
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Yeah I'd be open to that at this point. I really wish I could figure out what I'm doing wrong with mine.
 
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Another point though, wouldn't you think that if I was making any of these mistakes, that I would end up with different shorts? Why is it always the 3.3 while all others are correct?
 

Stitches

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It's so strange! And getting increasingly frustrating. Does the U10 not being moved have anything to do with it potentially?
That probably won't have anything to do with it. U10 just provides a delayed reference signal to the Wii for logic calibration. The U5 footprint does have a live 3.3v feed in, but the output line doesn't go anywhere once the Wii is trimmed. You could desolder U5 and the 3 capacitors around it if you want to isolate the possibility that the short is some conductive debris sitting under U5. Doing so won't cause any additional problems, so might be worth the Hail Mary. I'd also recommend cleaning both sides of the board with IPA just to be sure.

Another point though, wouldn't you think that if I was making any of these mistakes, that I would end up with different shorts? Why is it always the 3.3 while all others are correct?
The weird thing is that to my knowledge the only way to have a short between 3.3v and ground is a physical conductive bridge. There's no visual evidence of that on the top/bottom faces of the boards, so I'm very much stumped. Unless perhaps some conductive debris got under the CPU/GPU during trimming, but you said that you taped them prior to trimming? Might be worth taking a magnifier and inspecting around the trim edges to be sure that you don't have any stubborn flakes of copper bridging between the layers. I can't think of much else that could cause this repeated issue. You'd think it must be something that you've done each time, but I don't know what that could be. It's a head scratcher, that's for certain.
 
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