Gentlemen,
An app note I was referred to recently (Nichicon source IIRC) stated that even new electrolytic caps should have their oxide layer reformed before being put into service if they've been on the shelf for as little as 12 months. They suggested doing this by charging them to 90% of max stated voltage via a 1k resistor and leaving them fully charged for 30 minutes. thereafter. This gives the oxide layer a chance to reform, they say. It's actually quite a rapid charge in most cases and certainl much faster than we would use for bringing vintage/NOS caps back to a serviceable condition. But for convenience you can't beat it. Anyway, cut a long story short. Previously I've brought old test gear back to life by manually bringing the supply voltage up via a variac and monitoring the current for any 'abberent behaviour' which is rather time consuming. In future I think I'll just use a 10k say resistor in the hot wire and leave it to its own devices, plugged in and switched on for 12 hours. That should be suitably kind to vintage equipment. But then I thought - would this still work if the equipment in question had an SMPS? It's fine for linear PSUs, but SMPS? Anyone care to offer an informed opinion?
CD.