Hi everyone,
I'm trying to fix a Japanese New 3DS (non-XL) I bought from eBay. It was listed as “for parts,” so I thought I would try to gain some experience by fixing it.
The original problem was that it would turn on for a couple seconds and then turn off abruptly with a pop and a flash on both screens. After doing some initial reading on the possible reasons, I was convinced that there was an issue with the connection between the components that were required to be connected for the unit to boot up (speakers, upper display, bottom display, etc.) and the motherboard itself. I opened the 3DS and found some corrosion around one of the flex cables and the corresponding connector. Some corrosion was also present on the surrounding capacitors, but I tested them with my multimeter, and they appeared to be OK. I didn't get pictures of the corrosion before I cleaned it up, but below are a couple of the area after.
Part of the contacts have corroded away, but I confirmed continuity between the flex trace and contact. After removing the corrosion with isopropyl alcohol, the pop turned into a short buzz, but still shutting down afterwards. At this point, I decided to power the board from my DC power supply so that I could connect the flex cables without having to hold the battery against the terminals in an awkward position every time. I used 3.7 V and a 100 mA current limit. After making sure that I connected everything properly, I tried turning the 3DS on, but this time, nothing happened. I tried using the battery again and still nothing happened, so I think I might have fried the ABXY board. However, I know that the system still charges or responds to the charger because when I plug in the charger, I can see the current draw from the charger to the 3DS increase from about 120 mA to about 560 mA (about 445 mA between battery and the terminals) when I touch the battery to the terminals. Again, everything was OK until I tried to power it from my DC power supply. I know that's probably the mistake and I should have done more research to check if I can substitute the battery for an external power supply before doing it.
What I've tried/checked:
Below are some additional photos of my unit for further inspection.
Any ideas where to go at this point? I've been thinking about ordering a replacement ABXY daughterboard, but I want to make an informed decision before I go further. I can provide more photos or details on what happened if necessary. I'm trying to learn as much as I can from this, so any input is greatly appreciated! 
I'm trying to fix a Japanese New 3DS (non-XL) I bought from eBay. It was listed as “for parts,” so I thought I would try to gain some experience by fixing it.
The original problem was that it would turn on for a couple seconds and then turn off abruptly with a pop and a flash on both screens. After doing some initial reading on the possible reasons, I was convinced that there was an issue with the connection between the components that were required to be connected for the unit to boot up (speakers, upper display, bottom display, etc.) and the motherboard itself. I opened the 3DS and found some corrosion around one of the flex cables and the corresponding connector. Some corrosion was also present on the surrounding capacitors, but I tested them with my multimeter, and they appeared to be OK. I didn't get pictures of the corrosion before I cleaned it up, but below are a couple of the area after.
What I've tried/checked:
- I tried reconnecting the vital bootup components and then attempting to turn it on again, but nothing changed.
- I tried leaving everything by itself without the battery for a while to see if that would help, but nothing changed.
- The battery fuse on the button side of the ABXY board and the fuse near the charging port is OK.
- Reseating the flex cable between the motherboard and daughterboard didn’t change anything.
- There are no continuity faults in the flex cable between the motherboard and power button.
- The LEDs light up when tested with the diode mode on my DMM, so they aren't blown.
- Directly measuring the red and black power wires going from the daughterboard to the motherboard shows 3.702 V, so I don't think there is any problem with the battery terminals.
- I don't know if the 3DS has CFW on it; I haven't been able to power it on to a point where I could see, nor did the unit arrive with an SD card.
Below are some additional photos of my unit for further inspection.
Daughterboard front view:
Daughterboard rear view:
Motherboard front view:
Daughterboard rear view:
Motherboard front view:
