CN3 is the VGA out, below the video controller and CPU, CN5 is the TTL com2 port.
I used the same cable pinouts as the i-Opener VGA cable (they are the same) below is the pin outs according to Wild_Pencil which worked fine for me:
CN3......VGA......Signal
1.........1.......RED
3.........2.......GREEN
5.........3.......BLUE
x.........4.......reserved
8,10......5.......GROUND
8,10......6.......RED GROUND
8,10......7.......GREEN GROUND
8,10......8.......BLUE GROUND
6.........9.......+5 VDC
8,10.....10.......SIGNAL GROUND
x........11.......montior ID Bit 0
2........12.......DDC Serial Data Line
7........13.......Horizontal Sync
9........14.......Vertical Sync
4........15.......DDC Data Clock Line