Brother HL-1650/1670N - Manual (Page 232)

APPENDIX
Appendix–31
The wire which is coloured blue must be connected to the terminal which is marked
with the letter “N” or coloured black or blue.
The wire which is coloured brown must be connected to the terminal which is
marked with the letter “L” or coloured red or brown.
The outer sheath of the cord must be secured inside the plug. The coloured wires
should not hang out of the plug.