LEESON NEMA 4X SCR Control: 174107.00 - Manual (Page 32)

26 Application Notes
Multiple Fixed Speeds
Replace the speed adjust potentiometer with series resistors
with a total series resistance of 10K ohms (Figure 10). Add a
single-pole, multi-position switch with the correct number of
positions for the desired number of fixed speeds.
S0502
S3
S2
S1
R4
R3
R1
TOTAL SERIES
RESISTANCE
10K OHMS R2
SO502 3-PIN HEADER
Use customer supplied
Molex connector #09-50-3031 to mate
with 3-pin header (SO502) on control board.
Figure 10. Multiple Fixed Speeds