Oh dear!
If the smoke came from the body of the machine it is likely the capacitor in the circuit board which has blown.
The 930s have an electronic circuit board inside the machine which has a capacitor on it, and these capacitors give up with age. When they fail they do so without warning and produce smoke.
I would advise anyone with a 930 to get it serviced regularly by a certified Bernina technician.
Although I clean and oil my 930 myself and have unlocked the seized-up mechanical parts it had when I got it, it goes to Bambers in Salford for a thorough service every couple of years so they can do the necessary checks on the circuit boards and the electricals.
The first time I sent it there they swapped out the old capacitor on the circuit board and replaced it with a new one, as a precautionary measure.
If I were you I would give Bambers a ring and ask their advice, they are really lovely and helpful. Their telephone number is 0161 707 7786.