Finally, I've implemented my USB power cable for my Takahashi TG-SP II, I did it because I got a failed USB device and thus the USB cable can be used for this purpose.
There is nothing special for this small project, the only thing to do is to make sure the cables are correctly connected. For the wiring diagram, you can refer to the link tomy USB batter box.
A Link to my USB battery box:-
And then you may want to check out my USB power cable idea below, to see why it will and why it won't work:-
And then one should be checking repeatedly with a multimeter on the polarity and voltage in the whole process, to make sure nothing went wrong. Make sure you don't use the data cable since it could carry Vcc as well. So, refer to the wiring diagram and check each cables end to end for the pin and cable correspondence.
Finally, I plug in the USB battery box above and my TG-SP II works! And I then plug it in my computer's USB and it works, too.