[Kevin Sevcik]

EDIT: Disregard the next paragraph...

I'm thinking this might be an oversight in the circuit design. The 78L05 series of regulators are rated for 100mA max output current. And the IR manual claims the circuit draws 100mA when an LED is on. Granted, that's a transient draw and the things are rated for occasional current peaks above that, but if it's been derated from overheating during the soldering process, then it could be marginal.

Of course, something could have just been shorted while you were testing it or something. At any rate, you should be able to find a 78L05 regulator of some brand at a local electronics shop that actualy carries things like resistors and caps and such. If you can find a 7805 or 78M05 regulator in a TO-220 package it'd probably be hardier, but you'd have to really try to jam it in to the same footprint, and heaven knows if any of this will be legal come kickoff.

EDIT: Whoops! I must have misread the IR manual, current draw is certainly not close to 100mA....