The following are possible causes for the TU-3 not powering on:
- The INPUT jack doubles as a power switch. Ensure the plug is firmly inserted.
- If running on battery, check whether the battery has been depleted.
- If using an AC adaptor, check the following:
- Use a BOSS PSA series adaptor. Operation with any other adaptor is not guaranteed.
- If powering multiple pedals via the TU-3's DC OUT jack, ensure the total current draw does not exceed the output current of your PSA adaptor (200 mA or 500 mA). For current draw of each BOSS effect, refer to the Specs tab on each product page. For PSA adaptor differences, see "BOSS PSA adaptor: Specification Differences by Model".
- If connecting to a BOSS BCB series pedal board (PSB-1U adaptor), ensure the total current consumption does not exceed 2000 mA. See "BOSS BCB Series (Pedal Board) Specification" for details. Note that connecting the PSB-1U directly to the TU-3 is not recommended, as it may cause noise.
If the unit still does not power on after checking all of the above, it may be faulty. Please contact your nearest dealer or our support team via Backstage.