Oki PT390 Manuel D'utilisation page 77

Then, press and hold down the FEED switch for one second or longer to
accept the selection. The printer prints the following when you accept the
selection of "MAX SPEED":
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
7. Select "5" as your option.
Press the FEED switch briefly (one second or less) until "5" is reached.
Then, press and hold down the FEED switch for one second or longer to
accept the selection.
11
11
10
9
8
7
6
5
4
3
2
1
SELECTION ITEM
MAX SPEED 5
MAX SPEED 4
↑
MAX SPEED 3
↑
MAX SPEED 2
↑
MAX SPEED 1
↑
MAX SPEED 11
MAX SPEED 11
MAX SPEED 10
MAX SPEED 9
MAX SPEED 8
MAX SPEED 7
MAX SPEED 6
MAX SPEED 5
MAX SPEED 4
MAX SPEED 3
MAX SPEED 2
MAX SPEED 1
SELECTION ITEM
Print speed for each option
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
MAX SPEED
75
11 (Max. 300 mm/s)
10 (Max. 280 mm/s)
9 (Max. 260 mm/s)
8 (Max. 240 mm/s)
7 (Max. 220 mm/s)
6 (Max. 200 mm/s)
5 (Max. 180 mm/s)
4 (Max. 160 mm/s)
3 (Max. 140 mm/s)
2 (Max. 120 mm/s)
1 (Max. 100 mm/s)