No wire gets connected to a +5v power source. Gets all its power straight from the 68k socket. The wire you might be thinking of gets soldered from one of the PAL chips to a point on the RAM daughtercard that was necessary in some early revisions if you had a DMA capable SCSI card in your system.
The chip that's missing is probably a PAL, so good luck finding a replacement
Here's a link to some more info:
http://amiga.resource.cx/exp/search.pl?product=vxl&company=
