On Fri, 28 Jun 2019 08:14:42 +0200 deloptes <delop...@gmail.com> wrote:
> Gene Heskett wrote: > > > There was a period a decade back where the capacitors > > were legendarily bad. Your unit may have some of them in it. > > It was around 2004. From a trustful source I understood that the > Chinese manage to steal the formula from Japan, but translated few > things wrongly and the world was flooded with bad caps. In the > company I was in back then, PC caught often even fire. We had to > mitigate the risk or just replace the PC with more reliable once. > This was a good story. > It was a Japanese problem in the 1990s. This type of capacitor was much smaller than previous types, so it was an obvious choice to use them everywhere. There was a surveillance camera that used over 100 of them. The problem was that they had various temperature ratings. Most had a life of 1000 or 2000 hours at their maximum temperature, which isn't very long when run continuously. This life roughly doubled for a 10 degree decrease in temperature. So when they ran cool, or in intermittently-used equipment, they were no trouble. But eighty degree capacitors running at fifty degrees might last around 10000 hours, which is about a year in continuous use. The unfortunate thing was that this type of capacitor failed in a way that previous types did not: it leaked electrolyte. This reduced the capacity and eventually caused many faults, which were worse when the equipment was cold. And the electrolyte dissolved copper, so a leaking capacitor would destroy the printed circuit tracks nearby... -- Joe
