Zerowatt ZTD Condenser & Heat-Pump Tumble Dryer: Drum motor drive semiconductor failure E09; motor triac shorted or direction reversing relay contacts burned on control PCB.
On Zerowatt tumble dryers utilizing ZTD condensation airflow duct system, bi-metal safety thermal cut-out, and electromechanical program timer: Heavy drum overload inducing high stall current, inductive voltage spikes from motor reversing, or PCB component fatigue.
Inspect control PCB for burned traces or cracked solder joints around motor relays. Test triac anode-cathode resistance with multimeter (must not be 0 Ω). Rotate dial to Off, press Start and Low Heat buttons for 5 seconds until the buzzer chirps twice, then release and turn to Off.
