OK, may NOT have been the brightest idea ever!
Got home, found a couple 12V 1A (and 12V 2AZ) power adapters with the right plugs in the big box of power adapters.
Fired up the laptop, plugged in the USB-C hub, plugged in a usb-powered HDD. Nothing. Shut everything down. Plugged in the external power adapter, got a green light on the USB-C hub, unplugged it, booted the laptop, plugged back in the USB-C hub, plugged in the power adapter, plugged in the usb-powered HDD, and the system saw it....... Viewed stuff, fiddled, copied. Then the green light went OUT on the hub...
Shut everything down, unplugged, rebooted. Plugged the USB-powered drive into a USB3 port and immediately started getting popups about the port not being able to deliver enough power. Unplugged it from the laptop and plugged it into the desktop and got the SAME popups no matter which USB3 port I plugged it into.
Plugged the hub back in and the laptop recognizes it, but no green light and it won't even read a flash drive.
I haven't pulled the USB-powered HDD out of the carrier and put it in a different carrier, but it appears I've destroyed the hub and at LEAST the HDD carrier, and possibly the drive...
Don't think I should try this with the other hub, which DOES still work on the USB-C port, though I haven't plugged in anything but a flash drive (and most likely won't)!
I've got a USB3 hub with a power adapter on order and a USB-C hub with a power adapter on order. Hopefully one of those will work and survive.
D’oh! My guess there is that you plugged a 12V power source into a hub that was probably designed for 5V and therefore didn’t have circuitry to step 12V down to USB’s standard 5V before passing power out to attached devices, which could definitely account for damaging both the hub itself and the carrier. I’m hoping the damage stopped at the HDD enclosure rather than the drive electronics themselves. The SATA connector that the carrier would use to connect to the drive actually delivers 3.3V, 5V, and 12V on different pins, but I’m not sure what would happen if it was receiving 12V when it expected 5V. Good luck!
As a FREQUENT practitioner of the "stupid human trick" I'd venture to guess that you're correct. Even though everything I've SEEN says to plug in a 12V supply to the hub, I may have the one that DOESN'T work that way. There's no voltage indicated on the plug, nor is there a manufacturer on the hub. They were purchased not long after buying the laptop a couple years ago, in the infancy of the USB-C, when there were VERY few choices.
It simply says "HIGH POWER SUPPLY SYSTEM" "USB3.0 HUB"...
Fortunately, I WASN'T stupid enough to plug in the OTHER hub and see what that one would do. I'll plug the HDD into the other usb-powered carrier and see if it works... I have more carriers if that one's fried, but I'd prefer not to replace the 1TB hybrid drive.