If you hit a pad and it does not respond occasionally, or the sound "cuts off," this may be due to the Crosstalk Cancel value being set too high for that pad.
First check and make sure the cable is functioning properly and that it is connected securely to both the pad and the Trigger input on the back panel of the TD-20. You may want to remove the cable from the jack(s) altogether and then reconnect it to confirm the connection. A bad cable or a loose connection can cause trigger problems.
Next, check and lower the X-Talk Cancel value for the the pad.
1. Press the TRIGGER button.
2. Press F4(XTALK).
3. Hit the pad.
4. Turn the VALUE dial counterclockwise to lower X-Talk Cancel (OFF-80).
5. Repeat steps 3-4 for any remaining pads if needed and continue to lower the value until the pad triggers consistently.
6. When you're finished, press KIT. The new settings are saved automatically.