[sf-lug] Weird USB problem, maybe hardware

[aaronco36 at sdf.org]

Re: Weird USB problem, maybe hardware

Quoting Akkana Peck <akkana at shallowsky.com> from
http://linuxmafia.com/pipermail/sf-lug/2022q1/015551.html :
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I've tried:
- three different USB A-to-micro cables
- different USB ports (the laptop's built-in USB3 ports, plus a
  powered USB2 hub connected to the other USB3 port)
- same Kobo and cable on an older laptop running a 2-year-old Debian
  (works fine, the Kobo shows the connect? dialog)
- Kobo and cable on the husband's Mac (shows the dialog)
- rebooting the CX1 into an older Ubuntu where this used to work
  (still no dialog, suggesting this is a hardware failure?)

I tried a voltmeter on the CX1 USB3 port, a port on the USB2 hub,
the USB2 port on the old laptop, and a cheap charge-only adapter.
All four gave +5 V on pin 1 (5.14 for the CX1's built-in USB3), 0 on
all the others. So whatever the difference is, it's not detectable
by a simple voltmeter test.

Anyone know what makes a computer's USB port look different from a
charge-only port? And is there a way to fix it if it fails?
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While the same "old" Kobo and cable may seem to work just fine solely on
the older laptop running Debian and on the husband's Mac, another question
I have is, Do you have possible access to a known fully-working Kobo of
the same or more recent vintage?
b/c use of a known fully-working Kobo together with the given test
machines and other highlighted variables could very well verify or else
reduce the possibility of hardware failure specifically within the "old"
Kobo.

-Aaron