Help! Rebote 2.5 Delay blowing PT2399!

[zencafe]

Hello!

I built a Rebote 2.5 couple months ago, it worked fine for about one month, then it stopped working... when I opened it I realized the 78L05 was blown, I thought it may have been a random failure, so I changed the 78L05 and the PT2399. It worked again for couple months, then the same happens, I've checked the whole board and I don't see any tracing/wiring mistakes, I even added a diode for inverse voltage protection. I'm really puzzled about this problem...
Sorry if this was discussed earlier, I searched and found now topics issuing this problem.

Thanks a lot in advance!

Best Regards.

D.