USE FLUX!!! I cannot understate the importance of it. It will allow the solder to bond much faster/easier.
Flux was used. Thanks for the reminder though.
USE FLUX!!! I cannot understate the importance of it. It will allow the solder to bond much faster/easier.
Bare wires are dangerous to use. It can ground/power/cross signals easily even if you try to be careful and tape off areas. Tape under and over the wires right by the soldering points in the 3DS to make sure other points on the board aren't getting touched. If you still can't get it to work then it seems it is on the SD side (assuming the wires aren't touching between the two ends). It is quite easy to solder to the wrong pins on an adapter card so that is a good reason to have a continuity tester around (touching the SD contact pins to the points soldered to on the 3DS to verify they are right). The last two possibilities are that the wires are too long (IIRC around 6 inches should be the max) or your SD card reader doesn't handle MMC cards properly.
Ok. The pics made it look like totally bare wires.
That reader should be fine then.
Does your 3DS boot up normally when the SD adapter isn't plugged in?
I just did this myself, and had similar issues. Resolved with different card reader.