I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen to have
a similar one going spare from a netbook which I no longer have.

Q1: is there any reason why this putative PSU wouldn't be fit for purpose -
ie is there any other characteristic other than 12V/3A that I need to
consider here?

Q2: Assuming we've made it past Q1 - unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to the
original, so it won't fit - both are standard-looking concentric plugs (ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these things -
how do I work out what plug I need to buy? I'm assuming it's possible to
buy a solderable version; otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)

Thanks for any thoughts
--
David

On 03/12/13 00:30, Lobster wrote:
I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen to have
a similar one going spare from a netbook which I no longer have.

Q1: is there any reason why this putative PSU wouldn't be fit for purpose -
ie is there any other characteristic other than 12V/3A that I need to
consider here?


The polarity of the plug- sometimes the centre is +ve, sometimes -ve.
Sometimes marked on the PSU or the socket on the device it powers.

Q2: Assuming we've made it past Q1 - unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to the
original, so it won't fit - both are standard-looking concentric plugs (ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these things -
how do I work out what plug I need to buy? I'm assuming it's possible to
buy a solderable version;


Maplin, CPC, or Farnell all sell plugs; they are specified by the length
of the metal connector, it's inside diameter, and inside diameter. It
can be tricky to measure, so you may have to buy a selection.

otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)


Probably the neatest way would be solder and heatshrink, but you should
be able to get a solderable plug.

Thanks for any thoughts
--
David

On 03/12/2013 08:33, Chris Bartram wrote:
On 03/12/13 00:30, Lobster wrote:
I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen to
have
a similar one going spare from a netbook which I no longer have.

Q1: is there any reason why this putative PSU wouldn't be fit for
purpose -
ie is there any other characteristic other than 12V/3A that I need to
consider here?


The polarity of the plug- sometimes the centre is +ve, sometimes -ve.
Sometimes marked on the PSU or the socket on the device it powers.

And sometimes annoying not marked at all on either part. It would have
been nice if there had been a manufacturers convention on polarity and
external diameter used for a given voltage, but it is pretty much
random. Centre positive is more common but there are exceptions

Q2: Assuming we've made it past Q1 - unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to
the
original, so it won't fit - both are standard-looking concentric plugs
(ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these
things -
how do I work out what plug I need to buy? I'm assuming it's possible to
buy a solderable version;


Maplin, CPC, or Farnell all sell plugs; they are specified by the length
of the metal connector, it's inside diameter, and inside diameter. It
can be tricky to measure, so you may have to buy a selection.

Allowing for delivery charges Maplin is probably easier for a one off.

otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)


Probably the neatest way would be solder and heatshrink, but you should
be able to get a solderable plug.

The ID is best measured by finding something like insulated wire or thin
rod that just fits inside and then measuring it that way.

You might need a couple of guesses to get the exact match, some
universal PSUs usually come with a selection of swapable connectors.

--
Regards,
Martin Brown

On 03/12/2013 00:30, Lobster wrote:
I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen to have
a similar one going spare from a netbook which I no longer have.

Q1: is there any reason why this putative PSU wouldn't be fit for purpose -
ie is there any other characteristic other than 12V/3A that I need to
consider here?

Sounds like it should be fine...

Q2: Assuming we've made it past Q1 - unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to the
original, so it won't fit - both are standard-looking concentric plugs (ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these things -
how do I work out what plug I need to buy? I'm assuming it's possible to
buy a solderable version; otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)

Solder and individual + overall heatshrink would do a neat job.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Lobster wrote:

I'm assuming it's possible to
buy a solderable version; otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)

A soldered on plug should be considered the worse of the two options as
they're a damn sight flimsier than splicing the two cables together. It
matters less for a monitor which doesn't move much but, having done
various laptops, joining the cables is the far more robust solution.

Also, IMO, if you find a solder plug the correct size, they tend not to
be as good a fitment to the socket.

To join the cables, two bits of heatshrink, one large, one small. Cut
the conductors 1cm apart (ie stagger the joins.) Large heatshrink pushed
over both conductors, small on one only - not doing both reduces the
bulge at the join. Big bit of heatshrink covers both joins.

--
Scott

Where are we going and why am I in this handbasket?

On Tue, 03 Dec 2013 09:00:10 +0000, Scott M
wrote:

Lobster wrote:

I'm assuming it's possible to
buy a solderable version; otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)

A soldered on plug should be considered the worse of the two options as
they're a damn sight flimsier than splicing the two cables together.
Also, IMO, if you find a solder plug the correct size, they tend not to
be as good a fitment to the socket.

To join the cables, two bits of heatshrink, one large, one small. Cut
the conductors 1cm apart (ie stagger the joins.) Large heatshrink pushed
over both conductors, small on one only - not doing both reduces the
bulge at the join. Big bit of heatshrink covers both joins.

Only one thing I'll add to that is I have known a conductor in a flex
break within the insulation where it enters the LV plug sleeve which
may be the cause of an apparent power supply failure.
The OP will probably know more but if there is any doubt it may pay to
check the plug by testing its barrel and socket with the flex
conductors with a meter or even a torch lamp and battery and giving
the flex entry a good wiggle.
It would be a shame to go through the work of connecting the old plug
to the other power supply and find it still doesn't work.
and don't cut the flex too near the plug,leave plenty to make further
joining attempts with if the first one doesn't go well.

G.Harman

In article , Scott M
writes

To join the cables, two bits of heatshrink, one large, one small. Cut
the conductors 1cm apart (ie stagger the joins.) Large heatshrink pushed
over both conductors, small on one only - not doing both reduces the
bulge at the join. Big bit of heatshrink covers both joins.

Solder jointing would be my approach too, yes to the staggering although
use of heatshrink on the inner cores can be problematic for the
inexperienced (shrinking the sleeve whilst soldering in close
proximity). A plain sleeve on the inner may be easier and it will be
well held by the outer heatshrink or no inner sleeve at all if the
stagger is long enough to avoid any risk of shorting. A spare bit of
outer cable sheath or a few turns of tape (my pref self amalg) will
match the bulk of the join to the outer of the original before applying
the outer heatshrink.

Also, best to make the join at least 6" from the plug as flexibility
will be reduced at the join.

Alternatively, split the cases on the psus and swap the leads over. Take
some care in rebuilding the strain relief on the cable, they're usually
moulded on the cable and sod's law dictates that they will be different.
--
fred
it's a ba-na-na . . . .

In article , Lobster
writes

unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to the
original, so it won't fit - both are standard-looking concentric plugs (ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these things -
how do I work out what plug I need to buy?

It's a 3.5mm jack plug, but they come with internal diameters of 2.1 and
2.5mm. Your 'new' PSU has the 2.1mm 'ole and you're trying to get it
into a socket with the 2.5mm pin.

Cut the cable off the dead PSU and splice it onto the working one. Use
heatshrink sleeving to make a neat joint.

And DOUBLE CHECK you have the polarity right if you don't want to let
the magic smoke out.

--
(\_/)
(='.'=)
(")_(")

On 03/12/2013 00:30, Lobster wrote:
I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen to have
a similar one going spare from a netbook which I no longer have.

Q1: is there any reason why this putative PSU wouldn't be fit for purpose -
ie is there any other characteristic other than 12V/3A that I need to
consider here?

Q2: Assuming we've made it past Q1 - unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to the
original, so it won't fit - both are standard-looking concentric plugs (ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these things -
how do I work out what plug I need to buy? I'm assuming it's possible to
buy a solderable version; otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)

Thanks for any thoughts
--
David

Be very careful! If the two power supplies have different IDs, it's for
a good reason. One will be stabilised and the other won't. An
unstabilised supply will produce a much higher voltage under no load
conditions, and relies on the load to bring the voltage down to the
required level. The plugs are designed to be different in order to make
them non-interchangeable. If you use an unstabilised supply with
something which requires the supply to be stabilised, damage may occur!
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

In article ,
says...

Be very careful! If the two power supplies have different IDs, it's for
a good reason.

And one of those good reasons is if they were made by different
manufacturers.

Or even by the same manufacturer, and built on the same production line
- but supplied to different OEMs who want their part numbers printed on
it.

Things are never that straightforward.


--
Sam

Roger Mills wrote:

Be very careful! If the two power supplies have different IDs, it's for
a good reason. One will be stabilised and the other won't. An
unstabilised supply will produce a much higher voltage under no load
conditions, and relies on the load to bring the voltage down to the
required level. The plugs are designed to be different in order to make
them non-interchangeable. If you use an unstabilised supply with
something which requires the supply to be stabilised, damage may occur!

Cor, where you been living for 10 years? They're all switched mode these
days and churn out the whatever voltage it says on the label. Different
sized plugs is manufacturers playing silly buggers.

--
Scott

Where are we going and why am I in this handbasket?

Mike Tomlinson wrote:

It's a 3.5mm jack plug, but they come with internal diameters of 2.1 and
2.5mm. Your 'new' PSU has the 2.1mm 'ole and you're trying to get it
into a socket with the 2.5mm pin.

Cor, where you been living for 10 years? There's about 4 different
diameters of centre pin and 5 different outer diameters.

--
Scott

Where are we going and why am I in this handbasket?

On 03/12/2013 00:30, Lobster wrote:
I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen to have
a similar one going spare from a netbook which I no longer have.

Q1: is there any reason why this putative PSU wouldn't be fit for purpose -
ie is there any other characteristic other than 12V/3A that I need to
consider here?

Q2: Assuming we've made it past Q1 - unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to the
original, so it won't fit - both are standard-looking concentric plugs (ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these things -
how do I work out what plug I need to buy? I'm assuming it's possible to
buy a solderable version; otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)

Thanks for any thoughts
--
David


When my Dell laptop PSU failed, the fault turned out to be where the low
voltage cable came out. So a repair was just possible although the
original case had to be cut open.


--
Michael Chare

Martin Brown wrote:

And sometimes annoying not marked at all on either part. It would have
been nice if there had been a manufacturers convention on polarity and
external diameter used for a given voltage, but it is pretty much
random. Centre positive is more common but there are exceptions

Cor, where you been living for 10 years? (I'm going to get bored of this
but not before you lot are.) Remembering the days of them being a
hotch-potch of polarities, I always check any switched mode wallwarts
that come my way amd I've not found a PSU with a negative centre pin for
years, probably not since the days of having actual transformers in them.

--
Scott

Where are we going and why am I in this handbasket?

Roger Mills grunted in
:

On 03/12/2013 00:30, Lobster wrote:
I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen to
have a similar one going spare from a netbook which I no longer have.

Q1: is there any reason why this putative PSU wouldn't be fit for
purpose - ie is there any other characteristic other than 12V/3A that
I need to consider here?

Q2: Assuming we've made it past Q1 - unfortunately the (LV) plug
which connects to the monitor is slightly but crucially differently
sized to the original, so it won't fit - both are standard-looking
concentric plugs (ie this sort of thing: http://tinyurl.com/mx35688)
but the central pin is evidently larger on the monitor than it was on
my netbook (though the external diameter looks the same). What are
the specs for these things - how do I work out what plug I need to
buy? I'm assuming it's possible to buy a solderable version;
otherwise everything I have here is welded together - is there a neat
way of cutting and rejoining the LV flex so I could recycle what I
have? (I wouldn't want to bodge it as I'll probably pass this monitor
on to someone else once it's repaired...)

Be very careful! If the two power supplies have different IDs, it's
for a good reason. One will be stabilised and the other won't. An
unstabilised supply will produce a much higher voltage under no load
conditions, and relies on the load to bring the voltage down to the
required level. The plugs are designed to be different in order to
make them non-interchangeable. If you use an unstabilised supply with
something which requires the supply to be stabilised, damage may
occur!

Thanks to all for the replies.

How would I know if one PSU was stabilised? There's nothing relevant
written on either of them AFAICS. The working PSU was a laptop charger -
is that likely to mean it might be stabilised and that the purpose-
supplied item for a monitor might not have been?

--
David

Scott M explained on 03/12/2013 :
Lobster wrote:

I'm assuming it's possible to
buy a solderable version; otherwise everything I have here is welded
together - is there a neat way of cutting and rejoining the LV flex so I
could recycle what I have? (I wouldn't want to bodge it as I'll probably
pass this monitor on to someone else once it's repaired...)

A soldered on plug should be considered the worse of the two options as
they're a damn sight flimsier than splicing the two cables together. It
matters less for a monitor which doesn't move much but, having done various
laptops, joining the cables is the far more robust solution.

Also, IMO, if you find a solder plug the correct size, they tend not to be as
good a fitment to the socket.

To join the cables, two bits of heatshrink, one large, one small. Cut the
conductors 1cm apart (ie stagger the joins.) Large heatshrink pushed over
both conductors, small on one only - not doing both reduces the bulge at the
join. Big bit of heatshrink covers both joins.

If there is a good staggering of the joints, one large heat-shrink will
cover it and be neater/slimmer.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

En el artículo , Scott M
escribió:

Cor, where you been living for 10 years? There's about 4 different
diameters of centre pin and 5 different outer diameters.

Bet you that what the OP has is a 3.5 mil jack plug though.

--
(\_/)
(='.'=)
(")_(")

On 03/12/2013 12:49, Mike Tomlinson wrote:
In article , Lobster
writes

unfortunately the (LV) plug which
connects to the monitor is slightly but crucially differently sized to the
original, so it won't fit - both are standard-looking concentric plugs (ie
this sort of thing: http://tinyurl.com/mx35688) but the central pin is
evidently larger on the monitor than it was on my netbook (though the
external diameter looks the same). What are the specs for these things -
how do I work out what plug I need to buy?

It's a 3.5mm jack plug, but they come with internal diameters of 2.1 and

Its not a jack plug... they don't have a hole in the end!




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 03/12/2013 23:18, Lobster wrote:
Roger Mills grunted in
:

On 03/12/2013 00:30, Lobster wrote:
I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen to
have a similar one going spare from a netbook which I no longer have.

Q1: is there any reason why this putative PSU wouldn't be fit for
purpose - ie is there any other characteristic other than 12V/3A that
I need to consider here?

Q2: Assuming we've made it past Q1 - unfortunately the (LV) plug
which connects to the monitor is slightly but crucially differently
sized to the original, so it won't fit - both are standard-looking
concentric plugs (ie this sort of thing: http://tinyurl.com/mx35688)
but the central pin is evidently larger on the monitor than it was on
my netbook (though the external diameter looks the same). What are
the specs for these things - how do I work out what plug I need to
buy? I'm assuming it's possible to buy a solderable version;
otherwise everything I have here is welded together - is there a neat
way of cutting and rejoining the LV flex so I could recycle what I
have? (I wouldn't want to bodge it as I'll probably pass this monitor
on to someone else once it's repaired...)

Be very careful! If the two power supplies have different IDs, it's
for a good reason. One will be stabilised and the other won't. An

Can't say I have ever seen enough standardisation of plug specs to draw
that conclusion.

unstabilised supply will produce a much higher voltage under no load
conditions, and relies on the load to bring the voltage down to the
required level. The plugs are designed to be different in order to
make them non-interchangeable. If you use an unstabilised supply with
something which requires the supply to be stabilised, damage may
occur!

Thanks to all for the replies.

How would I know if one PSU was stabilised? There's nothing relevant
written on either of them AFAICS. The working PSU was a laptop charger -
is that likely to mean it might be stabilised and that the purpose-
supplied item for a monitor might not have been?

Its is almost guaranteed that both will be switched mode supplies (and
hence regulated / stabilised)

(a 12V 3A linear supply would be quite a hefty brick and probably weigh
as much as the laptop!)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm grunted in
news
On 03/12/2013 23:18, Lobster wrote:
Roger Mills grunted in
:

On 03/12/2013 00:30, Lobster wrote:
I have a flatscreen monitor whose (separate) PSU has died and needs
replacing. It's a 12V 3A unit, and as luck would have it I happen
to have a similar one going spare from a netbook which I no longer
have.

Be very careful! If the two power supplies have different IDs, it's
for a good reason. One will be stabilised and the other won't. An

How would I know if one PSU was stabilised? There's nothing relevant
written on either of them AFAICS. The working PSU was a laptop
charger - is that likely to mean it might be stabilised and that the
purpose- supplied item for a monitor might not have been?

Its is almost guaranteed that both will be switched mode supplies (and
hence regulated / stabilised)

Thanks John. Looks like the next step is to try and get inside the welded
faulty PSU without damaging it, and work out whether it's the flex that's
broken or the electronics; if the flex is OK I'll transfer it to the new
PSU via solder/heatshrink.

--
David

Mike Tomlinson wrote:
En el artículo , Scott M
escribió:

Cor, where you been living for 10 years? There's about 4 different
diameters of centre pin and 5 different outer diameters.

Bet you that what the OP has is a 3.5 mil jack plug though.

I'm confused why you keep saying jack plug. Power plugs are quite
different in design and I don't think have ever had any parameter of 3.5mm.

--
Scott

Where are we going and why am I in this handbasket?

In article , Scott M
writes

I'm confused

Clearly.

--
(\_/)
(='.'=)
(")_(")