Since you have a 2 PS bar, most likely the one PS powers the 4 corners and the other PS powers the 4 inners... Just to thoroughly check, switch the outputs of the 2 PS's... If you switch them and the opposite set of strobes fire then the ps is shot, but if the same set of strobes fire, then the other strobe heads are shot... It's highly unlikely that you have 4 strobes out, but it it possible... But since you stated that the bar was smoking, I would still assume that the one PS is now shot...