This week I received an old photographic studio flash unit made in the early 1960'ies. Inside is a huge 40µF/2500V capacitor. I don't know the usage history of the unit; it may not have been used for 20 years or perhaps more, or it may have been used weeks ago.
What is a safe way to bring the unit back into use again? I am thinking of interrupting the mains supply (240VAC) with a relays, operated by a microcontroller, starting with 0.1s pulses and a few minutes waiting time, slowly building up. Would that be a good idea, or should I follow another approach?