[TechAssist] Re: compaq presario 900 power supply adapter
- From: "J Silverman" <greentron@xxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Fri, 29 Aug 2003 13:16:02 -0400
Every once in a while some newby mfr comes along with something with the
adapter center terminal negative, but after a few disasters when using the
automobile adapter version, the next models have the center terminal
positive.
Jerry Silverman
Greentron Inc
4 Newland Ave
Greenville SC 29609
864 232 3889
Fax 271 2080
mailto:greentron@xxxxxxx
----- Original Message -----
From: "George" <grndmstrg@xxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, August 29, 2003 2:39 AM
Subject: [TechAssist] Re: compaq presario 900 power supply adapter
>
> 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
> > >
> > >
>
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> > --
> >
> >
> >
> >
> > Gary McCartney
> >
> > McCartney Electronics
> > Guelph Ontario Canada
> > Est. 1984
> > email: gary (at) number63.ca
> >
> >
>
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