hello howard, the dec express takes 12 volts with the center pin 
being positive and if you put a reversed polarity adapter on the dec 
express it will cause a diode to conduct and blow the chip fuse and 
from then on no adapter will work.  i sent you info earlier when you 
first asked your question telling you where to get a regulated 
adapter for the express but guess you didn't follow my advice.  take 
care and c u mike



At 04:07 AM 10/30/2012, you wrote:
>Every other twelve volt supply I have tried doesn't work, no matter what the
>polarity is.  Very odd!