Electrolytics are usually nothing too fancy, but it is proprietary. Water and electrolytes, hence the name. PCBs are in the big transformers and what used to be

Electrolytics are usually nothing too fancy, but it is proprietary. Water and electrolytes, hence the name. PCBs are in the big transformers and what used to be called bathtub caps which looked like this https://i.ebayimg.com/images/g/VjwAAOSwfGJjYtHx/s-l400.jpg https://i.ebayimg.com/images/g/VjwAAOSwfGJjYtHx/s-l400.jpg (think 1950s electronics stuff)