Solution 2
Print a Bk image in the four-colors (YMCK) printing from the command workstation.
Select [Job Properties].
Select [Color] tab.
Select [Expert Settings] in color mode.
Select [Gray & Black Processing Options].
Select [Normal] in [Black text and graphics] to print the black text and graphics as a four-colors black using C, M, Y, and K toner.
If you select [Pure Black On] in [Black text and graphics], the machine prints black text and graphics as a one-color black, using black toner only.
After taking the above measures, do the color calibration adjustment of the external controller.
