Anyone who ever revived Discmans or AIWA walkmans knows that some electrolytic capacitors turn Bad. And Bad in an ugly way: instead of just drying out they leak acid, damage the board and fight back with real nasty fumes when you desolder them. We discussed this a bit here, another theory that I picked up was that during the first few years (mid-eighties?) of SMD electrolytics they did not fix all the production glitches. Wikipedia says: A stolen recipe ... led in the years 2000 to 2005 to the problem of mass-bursting capacitors in computers and power supplies, which became known under the term "Capacitor Plague". In these capacitors the water reacts quite aggressively and even violently with aluminum, accompanied by strong heat and gas development in the capacitor, and often leads to the explosion of the capacitor. Here is a similar (the same?!?) detective story, but set in "around 1990", so maybe related to our headaches: page 55 from How to Diagnose and Fix Everything Electronic, Second Edition and its cover: Excellent tutorial for the beginner like me, I would even say that out of a dozen books on the subject that I bought over the last years this is the best
