Cursitor Doom wrote:

When connected to an external bench power supply at 12V., the board draws
9.3mA. The bench PSU doesn't have any issues powering this board.

When connected to PSU that uses the LM317, however, it draws 3mA and the
voltage across it drops to around 6V.

If the current requirements are that low, why don't you use something like
the LM7812 instead of the 317?

They are far simpler to use, aren't as flakey as the 317 and about as cheap.

Unless the supply the 317 is in is needed to be voltage adjustable or
high current (or higher than a LM78xx can produce), you'll save a lot of
hair pulling using the LM7812.

-bruce