Amplifier baseline offset adjustment
If the signal from the amplifier is not on zero, it is possible to remove the offset by using the Zero Adj screw at the top of the amplifier.
Make sure that the amplifier is set to the correct mode (AC/DC), the filters are adjusted correctly for the signal, and the electrodes or transducer is connected.
Slowly turn the Zero Adj screw to adjust the zero position.
Optional: Adjust the vertical scale to see the small changes that occur when you turn the screw.
Note that if the gain is set too high the signal could rail at +10 or -10 Volts. It is sometimes easier to perform the adjustment if the gain is reduced. Turning the screw clockwise will move the signal up.
The zero position should not require constant adjustment. The amplifiers are very stable, and once the baseline has been set, it should not require further adjustment.