tc electronic "polytune" service mode

I found the service mode of tc electronic "polytune" unexpectedly .

1. Insert the 1/4" phone plug into input jack for power on with holding the [display] and [tuning] button.
2. It display version?  number.
3. Press [bypass] foot sw.
4. Start display test.
5. Use [display] and [tuning] button testing LED display.
6. Finaly, press [bypass] foot sw to return normal mode.

• #music
• #polytune