[PLUG] Failure Mode in 20 volt Power Adapters

[wes]

the center pin is a "data" line, the computer uses it to identify the power
adapter powering it. the computer may refuse to do things like run at full
speed, or charge the battery, if it cannot verify that the power adapter is
capable of handling that load.

I think it's some sort of fire prevention scheme?

-wes

On Wed, Jan 27, 2016 at 2:43 PM, Dick Steffens <dick at dicksteffens.com>
wrote:

> I think "failure mode" is the right expression, but I'm sure if it's not
> I'll soon be educated. :-)
>
> That Thinkpad I just got came with a battery but no power adapters. I
> went to the Tualitin Best Buy to see what I could find. The nice young
> lady there brought out a generic brand power adapter. She took it out
> and we plugged it in. No juice. We didn't know why, but we guessed that
> I might need something specifically designed for Lenovo products.
>
> I went home, found both wall power and car power adapters online and
> ordered them. When they came, I tried each of them. No juice. So then I
> started studying how they work. I was not familiar with this type
> before. I thought that the outer sleeve of the plug would be - and the
> inner pin would be +, but was surprised to learn that the center pin is
> not connected, and that there is an inner sleeve that handles +. As I
> studied the socket on the laptop I saw two springy parts, and they
> looked like they were squeezed towards the center of the socket. From
> many years' experience with light sockets where the center contact gets
> squished too often and needs to be pulled up a bit -- ALWAYS PULL THE
> PLUG FIRST! -- I thought I'd try spreading out those springy parts. I
> took out the battery first, although I don't know if it was necessary.
> Sure enough, spreading those springy parts fixed it. Both the house
> power adapter and the car power adapter work fine.
>
> Another little bit of knowledge to tuck into the tool box.
>
> --
> Regards,
>
> Dick Steffens
>
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