I send an API packet to a breadboarded XBee S2 to set pin 19 / DIO1 high. To verify, I have an LED connected to that pin. I also have an LED connected to pin 15 / Association. When I apply power the Ass’n LED lights, then blinks. No problem. When I send a packet to turn on DIO1, that LED turns on. Within seconds the 3.3V regulator in a chip (TO-220 package) gets hot and the XBee gets hot and so I disconnect power. The XBee never works again. I’ve put in a 2k ohm resister on both pins. Doesn’t help. What could be the problem? I’ve gone through 7 XBees so far.
Note: the regulator is outputting a bit under 3.65 V. I tried swapping another new identical regulator. It does the same. When I first used these regulators a few days ago, I recall them putting out 3.33 V on the dot. Something strange going on with that also.