Connected NC pin of 5V regulator to GND

chatgpt answered this way, but could not provide a source for its answer L:



I guess next best thing is ohmmeter the pin with respect to ground, also to its Vdd.

You may need a backup plan in case you subsequently discover that NC means exactly that and nothing else.

The two 3-pin packages for the LM78L05 have only got three connections, so there are only going to be two bond wires with the back of the IC die on the central pin. On the SOIC and the SOT-89 package, there are multiple ground pins, and I guess that the pins are all formed from one bit of metal.

Pins 4 and 5 of the SOIC are NC, which is different from the four middle pins that are ground. Pins 4 and 5 won't be connected to anything.

You can test it easily.