Using the Electro - Harmonix 2020 Guitar Effects Pedal Tuner is easy. First, connect it to your guitar and pedalboard using the appropriate cables. Then, turn on your guitar amp. When you want to tune your guitar, simply step on the tuner pedal. The high - visibility display will show you the note and how close it is to being in tune. To adjust the calibration, use the calibration settings to set it between 436 - 445hz in 1 hz steps. You can also choose from three flat tuning modes according to your needs. When using it live, remember that the output is muted when the tuner is engaged, so you can tune quietly. As for maintenance, keep it in a dry place and avoid dropping it. If it's not working properly, check the power adapter and cables to make sure they're connected correctly.