USB power draw on Prusa Mini

What is the problem?

I have connected a Webcam (Logitech C525) to my Octopi but when the printer connects to Octoprint, the camera drops off and the power light goes off. I have tried to tape over the power pin on the USB cable but then the printer wont connect to the Octopi.

So, if I turn the printer on first, then reboot the Pi both are working. The minute I go into Octopi and hit connect, the camera loses power. My power supply is supposed to be 5V 3.5A so it should be enough,

Any ideas?

you could try it with a powered usb hub

Are you sure you did tape the 5V and not the GND pin?
I had that once, looked at the cable on the wrong direction. At first the results look the same but then there is no or very poor connect.

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I got a powered hub and it only works if I connect the printer to it instead of the camera. Got the camera up, printer up and connected. All good until I start the print then the camera goes off. I am completely stumped now

so the camera goes down even if the printer is connected to the powered hub?

yep as soon as I start a print the camera froze and then the power light went out.

I fear you may not be alone. Just to claify, which power light went out?

The camera light went out

Are you on a Pi4? If so try switching between the blue/non blue ports. Some of cameras only work in a specific port on the 4 but work fine in any port on a 3.

It looks like the power issue was solved when I disconnected the fan from the Pi. That seemed to allow enough power to keep the camera running

I had the same problem, I solved it this way. I isolated the USB for the camera by taping over the power pin. The usb cable to the camera goes to the output of a USB hub. (In my case I used an old KVM switch I had, same difference, it provides the power for the camera. The USB from the PI to the printer is connected to a different USB port on the PI (I have a Raspberry PI 3B+) The PC connects to the PI over ethernet. The PI is connected by Ethernet to my Cisco Router. I can then connect to it from all PC's on my home network.

Question: have you tested the fan?
I had a fan that interupted prints a lot. When I did a power-check, it was clear that it was sometimes drawing much more then it should and thus draining the power of the Pi or printer.
Just changing the fan was then enough to keep on printing. Was a hard time to find out that it was that small fan that caused all the issues.