Classic Electronics Repair: Reforming a high voltage electrolytic capacitor: Video 1. скачать в хорошем качестве

Classic Electronics Repair: Reforming a high voltage electrolytic capacitor: Video 1.

Hi Folks! Welcome to Video One on reforming high voltage electrolytic capacitors! Electrolytic capacitors have aluminum plates typically separated by paper soaked with a chemical mixture. At the factory, the capacitor plates are "formed" so that each plate has the right characteristics. Unfortunately, if electrolytic capacitors haven't been used in a long time, the plates will lose their properties (de-form) and become much more conductive. Picture a radio or other device that hasn't been used in decades suddenly being plugged directly into a wall outlet and turned on! The safe thing to do is to slowly run up the line voltage to the equipment over a period of time to give the capacitor a chance to slowly reform, or to use an external DC supply to reform the cap. Here, I'm going to use the Sprague Tel-Ohmic model TO-6 Capacitor Analyzer to slowly run up the voltage on an old electrolytic to see how it reforms. The Tel-Ohmic has a capacitor leakage setting that serendipitously allows you access to up to 600 Volts for re-forming. It also has an ammeter with a number of settings. For general re-forming, I like to use the 0-6 mA scale. In this test, I used a Simpson 260 VOM to monitor the voltage to ensure that 500 Volts was not exceeded. The process is to connect up the cap and initially run up the voltage to a convenient low current level (less than 6 mA in this case). As the cap re-forms, the current drops and the voltage rises. You then run the voltage up again, the current drops once more, and you wash/rinse/repeat until you get up to the rated capacitor voltage. Hopefully, you get to a point where the leakage is well under 1 mA. This capacitor is a 1940's vintage dual section 8-8 uF 475 VDC working voltage, 600 VDC maximum voltage unit from a McIntosh Electric Co. model 5018 electroshock therapy unit I'm evaluating to sell on Ebay. Please check out Video Two to see how the re-forming turned out. Thanks for watching! -Tom