Minolta Di551 Service Manual page 370

Overall halftone
No.1
Check item
When density is set to 70 (halftone)
If there are white stripes, black stripes, or uneven density, determine whether the fault is with the
scanner or the printer.
When density is set to 0 (white)
If the test pattern is gray background, determine whether the fault is with the scanner or the printer.
When density is set to 255 (black)
If the density is light, determine whether the fault is with the scanner or the printer.
* The above density settings are typical values. See [18] "Test pattern density setting" for more
information on density setting.
Test patterns
Density set to 70 Density set to 0
2-73
ADJUSTMENT
Density set to 255