Tantalum capacitors (was: LCIII Recap - Apple design fault -47uF reversed!)

On Fri, Apr 12, 2013 at 3:00 PM, Tothwolf <tothwolf at concentric.net> wrote: I glanced at the topic... looks like it turned out to either be a silkscreen "error" or it was on the -5V line for the comms drivers (or was it confusing the "black line" on an electrolytic cap and assuming the polarity was the same for the marking on an SMT tantalum cap?) c. 1984 I saw a COMBOARD returned from a customer because the tantalum cap that was acting as a ripple filter for the 74S409 DRAM controller had exploded while the board was installed in a crowded BA-11 box. It looked like someone shot the board with a .22. The damage included the board itself (replaced under warranty) and the boards on either side (not sure who paid for that but it was either my employer or perhaps the DEC Field Service contract - I'm sure the customer wasn't left holding the bag on that one). This was the only one I saw out of hundreds of boards shipped. We ran them 24/7 for years at a time and never saw one fail, but if it happens to you, it's quite the mess. -ethan