How to do moisture-proof treatment of electronic equipment used outdoors for a long time?

According to the withstand voltage of the capacitor to be tested, find a slightly higher than his DC power supply, and then series a large resistor, and an ammeter, it can be. According to the capacity of the capacitor to be tested and varieties of different resistor values and ammeter range selection is also different, to measure 25V1000μF electrolytic capacitors, for example, you can use a 50V DC power supply, series connection of 50K resistors and 1MA ammeter.