airnocker

Thanks @TomChiron, that was my expectation.

Thank you @AJL Electronics for your posts, I appreciate you responses but neither answer my question. (Yes, I'm aware I could drop the input voltage to the 7805, I've used this family of regulators for over 4 decades.) So allow me to rephrase my...

I'm attempting this now with a T4.1 with the USB5V-to-VIN trace cut such that the T4.1 USB connection provides GND, D- and D+ while a 7805 powered by a 12VDC wall wart provides regulated 5V to the VIN pin, the wall wart GND (V-) is tied to 7805...