[TechAssist] Re: compaq presario 900 power supply adapter
- From: "George" <grndmstrg@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Thu, 28 Aug 2003 23:39:57 -0700
Gary,
That should work with most of today's electronics because of general design
practices that assume npn devices and negative connected at ground reference
but this is not always the case. I have worked on many floating circuits
with positive ground reference using npn and negative ground reference using
pnp devices. This is done some times for compatibility and at other times
just to use up old inventories or bargain buys by the manufacturer.
George
Afana Electronics
Moreno Valley, CA
----- Original Message -----
From: "Gary McCartney" <gary@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, August 28, 2003 10:36 PM
Subject: [TechAssist] Re: compaq presario 900 power supply adapter
> Bob, I have a Compaq model 1230 here and the adapter plug has + 19V on
> the center terminal and ground on the outside.
>
> I have checked this sort of thing in the past where I didn't know which
> polarity to use on a laptop. I put my meter ground lead on the center
> terminal of the power jack in the computer and then tried touching
> various places on the computer where I thought might be at ground
> potential such as some of the case screws (if they happened to screw
> into metal frame behind). When I didn't notice any direct continuity
> from the jack to ground, I placed the ground lead on the outside
> terminal in the jack and then touched around at the screws etc. again.
> This time I was able to get zero Ohms from the terminal on the jack to
> the case screws. This told me that the center terminal was positive and
> the outside was ground.
>
>
>
>
> Gary McCartney
>
> McCartney Electronics
> Guelph Ontario Canada
> Est. 1984
> email: gary (at) number63.ca
>
>
>
>
>
> BearBuilder wrote:
> >
> > HI GANG
> > SOMETIMES it's the little things...
> >
> > Can anyone tell me the center tip polarity on a Compaq presario 900
laptop notebook power supply adapter ??
> >
> > THANKS
> >
> > Bob Hunter
> > Imagineering SODA
> > Van. BC Canada
> >
> >
****************************************************************************
*
> > Classifieds! Buy or Sell!
> > http://sell.tech-assist.org
> > The Tech Address Book:
> > http://www.tech-assist.org/secure/tip/contact.htm
> > Add a Repair Tip Here, or Change/Remove your Email Address:
> > http://www.tech-assist.org/secure/tip/main.htm
> > Lost Password:
> > http://www.tech-assist.org and select "Lost your Login Info?".
> > Email Archives:
> > //www.freelists.org/archives/techassist/
>
> --
>
>
>
>
> Gary McCartney
>
> McCartney Electronics
> Guelph Ontario Canada
> Est. 1984
> email: gary (at) number63.ca
>
>
****************************************************************************
*
> Classifieds! Buy or Sell!
> http://sell.tech-assist.org
> The Tech Address Book:
> http://www.tech-assist.org/secure/tip/contact.htm
> Add a Repair Tip Here, or Change/Remove your Email Address:
> http://www.tech-assist.org/secure/tip/main.htm
> Lost Password:
> http://www.tech-assist.org and select "Lost your Login Info?".
> Email Archives:
> //www.freelists.org/archives/techassist/
>
*****************************************************************************
Classifieds! Buy or Sell!
http://sell.tech-assist.org
The Tech Address Book:
http://www.tech-assist.org/secure/tip/contact.htm
Add a Repair Tip Here, or Change/Remove your Email Address:
http://www.tech-assist.org/secure/tip/main.htm
Lost Password:
http://www.tech-assist.org and select "Lost your Login Info?".
Email Archives:
//www.freelists.org/archives/techassist/
Other related posts:
