If the outer shield/ring/shell of the power connector is tied to chassis,
then that is your ground and the pin is the positive.
This is the most common configuration.
Your vm readings also seem to support this.

Plug away. Center pin=Hot +

Got2Go

"ML" wrote in message
...
Thanks for the reply, Got2Go,

The outer is definitely connected to chassis (I guess the shell of ext
video
connector is chassis, everything else is plastic!)
Putting v/m on diode test reads 3.48 with positive lead connected to
inner
pin rel to chassis and 1.06 with negative lead connected. Not easy to
judge
as there must be a charger circuit between the 22v input and the 14v
internal battery. There may also be a reverse volt protection on it as
well? I'm a bit nervous at taking a gamble!

Malcolm



Got2Go wrote in message
news:QUjbc.5516$zh.4049@fed1read07...
Malcolm,
You could try with a voltmeter.
Check for continuity between the pins and some metal part of the
chassis.

The pin that has continuity will be the negative one.

Another way that could work is to test the pins with the voltmeter set
to
diode test.
Put one lead on each pin, then reverse them.
If you get about 0.600 one way, and open reading the other way, then
your
positive pin is going to be the one with the red voltmeter lead when the
voltmeter reads open.
If you get values that do not match the above, then I would post them
here
before trying to plug it in.

Got2Go

"ML" wrote in message
...
Does anyone know the connector polarity for a Sharp A250 notebook
please?
I
have been given one without the external power unit and I want to test
it
before buying a new PS. The notebook label specifies an EA-J02V 22v
1.8Amp
ac adaptor, that connects with a 3.5/1.35mm connector.

I need to know is the center pin positive or negative to chassis?

TIA
Malcolm L
Somerset UK