[Mike]

Originally Posted by Andrew Blair

This same exact thing happened to us, though it lasted a lot longer than 40 seconds, maybe 5 or ten minutes. We had an enclosed box, with holes but no fans, and when we opened the box, afraid we'd killed our transformers, it had just gotten warm enough that the adhesive label on the transformers was peeling off. We redid the box, increasing it's size and adding a big fan. The problem went away; in fact, I believe that we have run it for like 6 hours straight. We are using a 12 volt, 1.5 amp power supply.

At first I thought it was overheating as well. I just took off the cover and it still happened. The box is made out of steel and we have that small (1 inch diameter?) muffin fan mounted in it.