[EE] proprietary power supply for HP/Compaq nx7300 - what is the function of cetral pin?
Wojciech Zabolotny
supply. Unfortunately, this laptop uses a nonstandard power supply
jack.
It features the inner and outer ring, which provide the high current
power supply, and also the thin central pin, which is used for ???
I have three hypotheses:
1. It may be used to control the operation of the AC charger from the
laptop (forcing the "power down mode"?)
2. It may be used as a feedback connection to provide better voltage control
3. (the conspiracy theory ;-) ) It may be a kind of serial interface
used to authenticate the original HP power supply to prevent using
other, cheaper adapters.
Does anybody know what is the real function of this central pin?
The original power supply looks like this:
http://www.topfreebiz.com/product/469522/Original-New-Laptop-Adapter-For-HP-18.5v-3.5a-Center-Pin.htm
--
TIA & Regards,
WZab
--
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Richard Prosser
> I use the HP/Compaq nx7300, which I need to power from the car power
> supply. Unfortunately, this laptop uses a nonstandard power supply
> jack.
> It features the inner and outer ring, which provide the high current
> power supply, and also the thin central pin, which is used for ???
> I have three hypotheses:
> 1. It may be used to control the operation of the AC charger from the
> laptop (forcing the "power down mode"?)
> 2. It may be used as a feedback connection to provide better voltage control
> 3. (the conspiracy theory ;-) ) It may be a kind of serial interface
> used to authenticate the original HP power supply to prevent using
> other, cheaper adapters.
>
> Does anybody know what is the real function of this central pin?
> The original power supply looks like this:
> http://www.topfreebiz.com/product/469522/Original-New-Laptop-Adapter-For-HP-18.5v-3.5a-Center-Pin.htm
> --
> TIA & Regards,
> WZab
> --
It's along the lines of option 3.
The computer checks with the power supply and limits some functions
depending on the reply. - and possibly the computer type.
IIRC the battery should still charge with a non-standard supply but
only at a low rate, and there may be a limit on charging while having
the laptop turned on.
YMMV
Richard P
Ruben Jönsson
> I use the HP/Compaq nx7300, which I need to power from the car power
> supply. Unfortunately, this laptop uses a nonstandard power supply
> jack.
> It features the inner and outer ring, which provide the high current
> power supply, and also the thin central pin, which is used for ???
> I have three hypotheses:
> 1. It may be used to control the operation of the AC charger from the
> laptop (forcing the "power down mode"?)
> 2. It may be used as a feedback connection to provide better voltage control
> 3. (the conspiracy theory ;-) ) It may be a kind of serial interface
> used to authenticate the original HP power supply to prevent using
> other, cheaper adapters.
>
> Does anybody know what is the real function of this central pin?
> The original power supply looks like this:
> http://www.topfreebiz.com/product/469522/Original-New-Laptop-Adapter-For-HP-18
> .5v-3.5a-Center-Pin.htm
> --
> TIA & Regards,
> WZab
I have the same one (or a very similar one - I can't remember the exact
modelnumber). The wires in the cable to the jack always gets pulled off after
some time use, especially the center wire (my kids are using it a lot). The
outer rings are connected to two separate screens in the cable but I think they
are connected together inside the powersupply. At one point the powersupply was
completely dead so I opened it up (with a lot of violince - the two halfes of
the enclosure are glued or welded together) and found that it was the soldering
on the mains inlet connector that had come loose from the circuit board due to
mechanical stress. It was at this time I think I saw that the two screens where
connected together but I am not quite sure now, it was some time ago.
I could probably take a closer look if you can't get the information from
someone else.
/Ruben
==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ru...@pp.sbbs.se
==============================
Michael Watterson
> I use the HP/Compaq nx7300, which I need to power from the car power
> supply. Unfortunately, this laptop uses a nonstandard power supply
> jack.
> It features the inner and outer ring, which provide the high current
> power supply, and also the thin central pin, which is used for ???
> I have three hypotheses:
> 1. It may be used to control the operation of the AC charger from the
> laptop (forcing the "power down mode"?)
> 2. It may be used as a feedback connection to provide better voltage control
> 3. (the conspiracy theory ;-) ) It may be a kind of serial interface
> used to authenticate the original HP power supply to prevent using
> other, cheaper adapters.
>
> Does anybody know what is the real function of this central pin?
> The original power supply looks like this:
> http://www.topfreebiz.com/product/469522/Original-New-Laptop-Adapter-For-HP-18.5v-3.5a-Center-Pin.htm
>
The Dell Inspirion 7500, 8200 and others use a 3 pin connector. On the
75W PSU for 7500 the extra pin is open, on the 90W 8200 PSU it's short
to +20V.
One 120W replacement PSU was recognised as a 75W PSU as the supplied
connector only had two pins connected. I replaced connector with the
original and the i8200 didn't complain of a low power. I eventually used
that PSU as 24V PSU and now use a different brand "2-power" 90W that is
identical to that supplied with a new Acer, but with the correctly wired
3 pin plug for Inspiron 8200.
Can you "open" the existing cable and see if it has actually any more
than 2 wires?
So I suspect it's either (2) above or same function as the Dell, a
simple indication of lower or higher rated units that have same connector.
I don't believe (1) or (3). That adds too much cost :-)
alan.b...@stfc.ac.uk
> > supply. Unfortunately, this laptop uses a nonstandard power supply
> > jack.
> > It features the inner and outer ring, which provide the high current
> > power supply, and also the thin central pin, which is used for ???
> > I have three hypotheses:
> > 1. It may be used to control the operation of the AC charger from
the
> > laptop (forcing the "power down mode"?)
> > 2. It may be used as a feedback connection to provide better voltage
> control
> > 3. (the conspiracy theory ;-) ) It may be a kind of serial interface
> > used to authenticate the original HP power supply to prevent using
> > other, cheaper adapters.
> >
> > Does anybody know what is the real function of this central pin?
> > The original power supply looks like this:
> >
http://www.topfreebiz.com/product/469522/Original-New-Laptop-Adapter-
> For-HP-18.5v-3.5a-Center-Pin.htm
> >
> It might simply be open or short.
>
> The Dell Inspirion 7500, 8200 and others use a 3 pin connector. On
the
> 75W PSU for 7500 the extra pin is open, on the 90W 8200 PSU it's short
> to +20V.
Most of the Dell power supplies have a dallas 1-wire device connected to
the 3rd pin. This gives the laptop information about the capability of
the attached power supply. See
http://www.howtofixcomputers.com/forums/dell/dell-pa-10-ac-adapter-cente
r-pin-108608.html for details, including the ROM contents of one version
of the chip.
--
Scanned by iCritical.
Michael Watterson
>
>
> Most of the Dell power supplies have a dallas 1-wire device connected to
> the 3rd pin. This gives the laptop information about the capability of
> the attached power supply. See
> http://www.howtofixcomputers.com/forums/dell/dell-pa-10-ac-adapter-cente
> r-pin-108608.html for details, including the ROM contents of one version
> of the chip.
>
The three pin in a triangle layout on keyed square connector as used in
early 2000s doesn't have any intelligence.
Oli Glaser
--------------------------------------------------
From: "Michael Watterson" <mi...@radioway.org>
> I don't believe (1) or (3). That adds too much cost :-)
It doesn't sound too unlikely to me - if by adding a bit of component cost
they can make sure people have to use their power supply then I think most
would go for it. The situation with laptop batteries is similar - I had to
hack one a while back as it had a lifespan set by the on board chip which
had expired, but the cells were still okay. Why make a battery that lives a
long time and has easily replaceable cells when you can do otherwise and
charge people half the cost of a new laptop for replacements? :-)
On a side note, whilst hacking the battery, I made use of this app note from
microchip on SMBus etc - quite useful:
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en011076
Oli Glaser
--------------------------------------------------
From: <alan.b...@stfc.ac.uk>
> Most of the Dell power supplies have a dallas 1-wire device connected to
> the 3rd pin. This gives the laptop information about the capability of
> the attached power supply. See
> http://www.howtofixcomputers.com/forums/dell/dell-pa-10-ac-adapter-center-pin-108608.html
> for details, including the ROM contents of one version
> of the chip.
Interesting link - so it's a little one wire eeprom, and it contains various
bits of info for the computer to recognise. Like the battery issue in that
it prevents anyone using other products - I wonder if the OPs power supply
is similar? Would have to pop it open to find out I suppose..
Michael Watterson
>
> It doesn't sound too unlikely to me - if by adding a bit of component cost
> they can make sure people have to use their power supply then I think most
> would go for it. The situation with laptop batteries is similar - I had to
> hack one a while back as it had a lifespan set by the on board chip which
> had expired, but the cells were still okay. Why make a battery that lives a
> long time and has easily replaceable cells when you can do otherwise and
> charge people half the cost of a new laptop for replacements? :-)
>
> On a side note, whilst hacking the battery, I made use of this app note from
> microchip on SMBus etc - quite useful:
>
> http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en011076
>
>
>
battery packs. It certainly doesn't stop cheap replacements.
The PSU issue is likely to use same connector on different ratings of
PSUs. It certainly doesn't stop cheap replacements.
It's not like Ink cartridges (where this certainly would apply). They
are not expecting to sell many replacement PSUs compared with laptops.
Oli Glaser
--------------------------------------------------
From: "Michael Watterson" <mi...@radioway.org>
Sent: Monday, June 21, 2010 12:30 PM
To: "Microcontroller discussion list - Public." <pic...@mit.edu>
Subject: Re: [EE] proprietary power supply for HP/Compaq nx7300 - what
isthefunction of cetral pin?
> Oli Glaser wrote:
>>
>> It doesn't sound too unlikely to me - if by adding a bit of component
>> cost
>> they can make sure people have to use their power supply then I think
>> most
>> would go for it. The situation with laptop batteries is similar - I had
>> to
>> hack one a while back as it had a lifespan set by the on board chip which
>> had expired, but the cells were still okay. Why make a battery that lives
>> a
>> long time and has easily replaceable cells when you can do otherwise and
>> charge people half the cost of a new laptop for replacements? :-)
>>
>> On a side note, whilst hacking the battery, I made use of this app note
>> from
>> microchip on SMBus etc - quite useful:
>>
>> http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en011076
>>
>>
>>
> The battery issue is for safety. Read up on failure modes of LiIon
> battery packs. It certainly doesn't stop cheap replacements.
> The PSU issue is likely to use same connector on different ratings of
> PSUs. It certainly doesn't stop cheap replacements.
Yes, I'm aware of the safety issue with LiIon cells, but I wasn't getting at
that - there is still some attempt to keep people buying their batteries,
there's plenty of reading on it out there. Whilst "smart" batteries that
control charge and monitor temperature are obviously a good an necessary
thing, there is also the fact that many batteries have a set life span
dictated by the firmware, and the cells are not easily replaceable (surely
providing some form of plug in replacement cells would not be unsafe?). I'm
sure they would say something like "we can't guarantee performance past a
certain date" with the set lifespan, but it's reasonably obvious that there
is some attempt to make it difficult to use anything but their stuff. When
you can but a set of replacement cells for £10, charging £200 for a
replacement battery seems a bit over the top, considering the contents.
If the PSU issue is like the Dell ones mentioned that use some form of IDing
on an eeprom connected to the middle pin, it would certainly make cheap
replacements more difficult.
alan.b...@stfc.ac.uk
connected to
> > the 3rd pin. This gives the laptop information about the capability
of
> > the attached power supply. See
> >
http://www.howtofixcomputers.com/forums/dell/dell-pa-10-ac-adapter-cente
r-pin-
> 108608.html
> > for details, including the ROM contents of one version
> > of the chip.
>
> Interesting link - so it's a little one wire eeprom, and it contains
various
> bits of info for the computer to recognise. Like the battery issue in
that
> it prevents anyone using other products - I wonder if the OPs power
supply
> is similar? Would have to pop it open to find out I suppose..
No he says his connector is an earlier one. I had a 12V adapter that
plugs into a car cigarette lighter socket, to run my laptop in the car.
It doesn't have the centre pin, and if I fire up the laptop on 'car
power' then I get a message from the BIOS that it cannot identify the
power supply. Another adapter I have does have an ident chip in it, and
when using this with a newer laptop that comes with a higher wattage
supply, I get a message about how it will take longer to charge the
batteries etc, with this supply.
--
Scanned by iCritical.
RussellMc
> battery packs. It certainly doesn't stop cheap replacements.
Certainly LiIon have more than their fair share of exciting halt and
catch (literally) fire modes*, but I'm not aware of any major LiIon
failure mode that increases as the cells age and lose capacity. It's
more likely that this is a "what the market will bear" attempt.
* Mechanical construction faults that short battery internally with
time or minor impact (!) (Sony and no doubt others), over voltage,
overcharge current, over discharge (some), over discharge current,
charge fast when too low a state, charge at all when too too low a
state, having a bad day, other ... . HP issued a recall notice on some
laptop LiIons a few months ago, it added to an existing list and they
added some more a few weeks ago. I own a "Compaq" laptop and an HP
netbook so receive related notifications.
Russell
Herbert Graf
> I use the HP/Compaq nx7300, which I need to power from the car power
> supply. Unfortunately, this laptop uses a nonstandard power supply
> jack.
> It features the inner and outer ring, which provide the high current
> power supply, and also the thin central pin, which is used for ???
> I have three hypotheses:
> 1. It may be used to control the operation of the AC charger from the
> laptop (forcing the "power down mode"?)
> 2. It may be used as a feedback connection to provide better voltage control
> 3. (the conspiracy theory ;-) ) It may be a kind of serial interface
> used to authenticate the original HP power supply to prevent using
> other, cheaper adapters.
AFAIK it's actually #3, it's often used to confirm "authenticity",
although in some cases it's used to determine how strong a supply it is
(on some Dells for example there are two supplies available, one is
strong enough just to power the laptop, while the second can power the
laptop and charge the battery, or something like that).
TTYL
alan.b...@stfc.ac.uk
> > used to authenticate the original HP power supply to prevent using
> > other, cheaper adapters.
>
> AFAIK it's actually #3, it's often used to confirm "authenticity",
> although in some cases it's used to determine how strong a supply it
is
> (on some Dells for example there are two supplies available, one is
> strong enough just to power the laptop, while the second can power the
> laptop and charge the battery, or something like that).
Yes the concentric one is #3 (see my first post on this thread). The two
sizes of supply are laptop only, and laptop + desk stand. However the
later models of laptop seem to need the higher power supply just for the
laptop.
--
Scanned by iCritical.
Michael Watterson
>> The battery issue is for safety. Read up on failure modes of LiIon
>> battery packs. It certainly doesn't stop cheap replacements.
>>
>
> Certainly LiIon have more than their fair share of exciting halt and
> catch (literally) fire modes*, but I'm not aware of any major LiIon
> failure mode that increases as the cells age and lose capacity. It's
> more likely that this is a "what the market will bear" attempt.
>
maybe the issue is that eventually the risk of thermal runaway due to
over discharge or in-ability to charge is increased when capacity is
very low due to age or large number of cycles. I can't find the paper I
was thinking of.
Anyhow, in practice you can buy 3rd party PSU brick or battery pack for
just about any Laptop/Netbook in last 10 years.
Though I'm puzzled why an Acer Travelmate battery is 60 Euro (not that
old of Laptop) and a higher capacity battery for Dell Inspiron 8200 is
24 Euro (> 10 year old laptop).
> * HP issued a recall notice on some
> laptop LiIons a few months ago, it added to an existing list and they
> added some more a few weeks ago. I own a "Compaq" laptop and an HP
> netbook so receive related notifications.
>
>
>
> Russell
>
Someone offered me 500 to 1000 LiPoly 24V packs withdrawn due to faulty
regulator design. I declined :) Even though maybe free*.
I was told that "most of the LiPolys are likely OK" But how would I
test? And I'd have to design my own replacement electronics. I don't
want to sell Incendiary Bombs (even though I'm from Norn Iron orignally).
The company that has these now ships battery packs with "fixed" design
of Electronics. I have to ask myself why are they not putting these
batteries in the new electronics if they are perfectly OK. Allegedly the
issue was not charging but regulation to the load (I guess maybe 6
cells, which of course is more like 13V to 27V than 24V?)
(* is the offer a cunning waste disposal scheme? and the shipping on 500
to 1000 battery packs... :( )