Tube arcing or a bad rectifier. Solution: The manual specifies a 3.15A slow-blow fuse for 115V operation and 1.6A slow-blow for 230V. Never use fast-blow fuses.
Ensure the unit is on a stable, level surface with plenty of ventilation. Tube amplifiers generate significant heat, especially those operating in Pure Class A. jadis da30 manual
Jadis DA30 : A Comprehensive Guide and User Insight The Jadis DA30 Tube arcing or a bad rectifier
This is the most critical maintenance aspect of the Jadis DA30. jadis da30 manual