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Can usb ports share a ground? Answered

Im converting an old printer (25 pin) switchbox into a switchbox that will be used for my monitor, speakers, keyboard, mouse and two computers. The problem is that the monitor has 15 pins, the speaker has 3 pins, and the two usb ports have 4 pins each meaning that I would need 26 pins rather that 25. I could just solder the left and right speaker pins together and make those two 1 pin, but i would rather not have to do that. My question is can two usb ports share a ground pin, meaning that it would only need 7 pins rather than 8.


Usb doesn't really have a ground, it has a negative.  But It should be okay to connect the negatives together.

but there is really no need to do that.  VGA has 4 pins that don't connect to anything.  Check out the vga pinout in this link.  It's down in the middle of the page.

Its more than likely that they share the same +5v power connection too but they almost certainly can share the same GND connection.

Are you certain that the monitor uses all 15 pins?

Not a good idea to just join the two speaker pins together.

Better make sure that the printer switch does switch ALL 25 connections because the old Centronics 25-way printer connections had a lot (probably half) of the connections were all Ground and so probably not included in the switching. If this is the case then you are out of luck - you'll probably have about 8 to 10 switched connections to play with and you will have to start thinking about sharing a lot of the grounds not just the two USB grounds.

Good Luck