[kwlug-disc] Strange poweron problem

[Jeff Smith]

Sorry I haven't responded to this in a while, but I think I found the culprit:  a USB 3 hub.  I purchased some USB hubs off of Amazon a few months ago, and I've noticed that all of them are showing signs of degradation already.  In the case of the one attached to this particular Ubuntu box, I swapped it right out and it the computer seems to be booting from the power-off state without any problems now.


I can't tell you what brand these USB hubs are, as they are no-name generic, but they are the ones with power switches for each port, and the USB cables are inserted on the very top of the hub.  I've had failures with three of these now.  I thought the individual power switches were a nice feature, but the rest of the hub is crap.


Cranky



________________________________
From: kwlug-disc <kwlug-disc-bounces at kwlug.org> on behalf of B.S. <bs27975.2 at gmail.com>
Sent: 25 July 2016 18:01
To: KWLUG discussion
Subject: Re: [kwlug-disc] Strange poweron problem



On 07/25/2016 10:59 AM, CrankyOldBugger wrote:
> I have an older machine running Ubuntu 16.04.  I'm having a strange problem
> with booting it.
>
...
> Sometimes after I do manage to get power on and we go through the POST
> Ubuntu will get stuck, but a repeat of power off, power on, unplug USB
> cable seems to clear that up.  I don't think this is related to the power
> issue but I can't rule that out yet.
>

Anyone know if any recent updates have come down involving USB hardware,
particularly around USB 3?

...
> If I try to power on from cold, the power switch does nothing.  No lights,
> no noise, nada.

This feels more like a short than anything else. Or you don't have the
bios set to power up at power on (i.e. after a power failure) - but that
feels unlikely as it would always have worked this way, and you wouldn't
have asked as it would be your normal.

It doesn't feel like a cable short, as you reported the issue remains
regardless of which end of the usb cable you leave connected.

I assume the hub and computer are on different power outlets, and when
you say power on from cold, the hub is powered on throughout and you're
not talking about turning a power bar on/off into which both are plugged
- power on is from the computer front panel power button itself.

> ... But if I unplug the USB cable in the back, the power
> switch lights up and away we go.  The USB cable in question is the only USB
> device attached, and it goes to a USB 3 hub on the desk which currently has
> my keyboard and mouse plugged in.  (It doesn't matter if I unplug the cable
> from the back of the PC or the hub itself, the results are the same.)
>
 > ...
>
> Any ideas?

First question is ... has anything changed recently?

I feel your pain and bafflement ... 3 computers here don't come up
properly after last nights power failure.

In any case, see if you can narrow down the culprit. Different behaviour
if you?:
- use a different USB port? USB 3.0 should bring nothing to this party
for just a keyboard and mouse.
- unplug the hub's power? (Nor should hub power matter, for this case.)
- direct connect without the hub?
- if it follows the hub, put both devices direct, with the hub
connected, then walk back to where you were until the problem reappears.

i.e. which component does the problem follow?


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