The suspect ones were blue. Apparently that batch was marked polarity reversed. They blowed up real good.. ;-).
Nobody in Corporate Engineering bothered to tell me about this minor issue so the first time I got the fireworks display I freaked out. Via a phone call to Engineering I was told to look at the circuit boards that failed and see if there were blue capacitors on them which of course was affirmative. When I asked what exactly I was supposed to do with this issue I was told swap out the boards until you find some that don't blow up.
If a circuit board got built with the defective units the only way to field test was power on and see what happens. We had some excellent pyro displays until they purged the stock. Freaked out several of the field techs who were with me when we started up the systems. One, after we arrived in the motor room, sent the helper on the coffee run, and set everything up asked 'What's the first step?' My reply was 'Turn on the main line and after the smoke clears change some boards.' He looked at me like I was nuts and said 'You're kidding.' I said 'Nope. Put the main on', which he did (or more correctly had the helper do.) Immediately the sound of fireworks, flashes of light, and white smoke emanated from the circuit board rack. The field tech was mortified. I just laughed hysterically. What I said would be the first step was exactly what happened.
Maybe I should have given the 'why' explanation before instead of after the light show...