You need to know the sense resistors exact value. The value that is adjusted from the pot is the voltage between two points. That voltage gives the current setting to drive the motors by formula A = VREF / (8 * RS). So for 0.05R sense resistors, about 0.3V of Vref will give you ~0.75A. In this case i would not try to go more than 0.3-0.4V coz it would set current probably too high. But you could have different sense resistors so may need to change the math accordingly.
I would set the Vref for all drivers while the motors are disconnected from the outputs. Then with correct vref settings, turn off everything, connect motor wires, and power up with motors. This is to avoid a situation where i would have the vref way beyond max, and the motor connected to the output with such a setting.
Do NOT disconnect the motors or fiddle with wiring when driver is powered up, coz this will probably burn the driver.
I would set the Vref for all drivers while the motors are disconnected from the outputs. Then with correct vref settings, turn off everything, connect motor wires, and power up with motors. This is to avoid a situation where i would have the vref way beyond max, and the motor connected to the output with such a setting.
Do NOT disconnect the motors or fiddle with wiring when driver is powered up, coz this will probably burn the driver.