Then one of their assistants said most stupid thing I've
> ever heard: *You need to install a proper driver for you microphone.*
> (I still have the chat log in my mail, LoL)
>
A usb-soundcard device microphone, presumably...Mind you, I've had them
tell me I need a driver for a router before now.

In message <KjPmh.2206$Fs2.1884@trnddc05>, mike <spamme9******.com>
writes
>M.I.5¾ wrote:
>> "mike" <spamme9******.com> wrote in message
>>news:Z6Mmh.1966$PN2.289@trnddc07...
>>
>>>M.I.5¾ wrote:
>>>
>>>><mc.preist******.com> wrote in message
>>>>news:1167770212.645064.150080@h40g2000cwb.goog legroups.com...
>>>>
>>>>
>>>>>I have a Dell Inspiron that comes with an 90W AC Adapter.
>>>>>It doesn't work and I need to open it. Does anyone know a nice way to
>>>>>open a Dell Adapter!?
>>>>>
>>>>
>>>>
>>>>Switch Mode Power Supplies (what you have) are very much a black art.
>>>
>>>Black art is the term you use when YOU don't understand something.
>>>Switching supplies are very much a known commodity.
>>>The problem is that the particular design is undocumented from the
>>>user point of view.
>>> The
>>>
>>>>chances of you repairing it are extremely slim at best.
>>>
>>>There you go again, projecting.
>>>Unless you really
>>>
>>>>know what you are doing, you are well advised to stay out of it.
>>>
>>> These
>>>
>>>>supplies contain internal voltages that can quite easily kill
>>>>(several thousands).
>>>
>>>kill several thousands of what? There ain't anything in that supply
>>>that's several thousands...oops, my bad, there are some resistors that
>>>are several thousands of ohms.
>>>
>> The supplies contain several thousands of volts, since the
>>converters are of the flyback type (generally the most efficient type).
>
>PUT a sample of this particular supply on the bench, put a scope on it
>and show me several thousand volts anywhere in it and I'll apologize
>profusely.
>Show me several thousand volts when it's unplugged and I'll eat
>it...with the power on!
>
I've hesitated to come in, but you're quite right. The highest voltage
you'll encounter is the supply voltage.

The reason why switched mode power supplies are not well understood -
even in product R&D departments - is because most equipment
manufacturers simply buy in the unit/module that they need. It's far
more economic to do so.

A good overview of switched mode power supplies (with explanations that
most should understand) can be found at:

http://en.wikipedia.org/wiki/Switched-mode_power_supply


--
Tony Morgan

On Jan 4, 12:38 am, "ric" <publicm...@infobubble.co.uk> wrote:
> A usb-soundcard device microphone, presumably...Mind you, I've had them
> tell me I need a driver for a router before now.

LoL

On Wed, 3 Jan 2007 16:11:04 +0000, Tony Morgan <Tony@rhylonline.com> wrote:

>In message <KjPmh.2206$Fs2.1884@trnddc05>, mike <spamme9******.com>
>writes
>>M.I.5¾ wrote:
>>> "mike" <spamme9******.com> wrote in message
>>>news:Z6Mmh.1966$PN2.289@trnddc07...
>>>
>>>>M.I.5¾ wrote:
>>>>
>>>>><mc.preist******.com> wrote in message
>>>>>news:1167770212.645064.150080@h40g2000cwb.goo glegroups.com...
>>>>>
>>>>>
>>>>>>I have a Dell Inspiron that comes with an 90W AC Adapter.
>>>>>>It doesn't work and I need to open it. Does anyone know a nice way to
>>>>>>open a Dell Adapter!?
>>>>>>
>>>>>
>>>>>
>>>>>Switch Mode Power Supplies (what you have) are very much a black art.
>>>>
>>>>Black art is the term you use when YOU don't understand something.
>>>>Switching supplies are very much a known commodity.
>>>>The problem is that the particular design is undocumented from the
>>>>user point of view.
>>>> The
>>>>
>>>>>chances of you repairing it are extremely slim at best.
>>>>
>>>>There you go again, projecting.
>>>>Unless you really
>>>>
>>>>>know what you are doing, you are well advised to stay out of it.
>>>>
>>>> These
>>>>
>>>>>supplies contain internal voltages that can quite easily kill
>>>>>(several thousands).
>>>>
>>>>kill several thousands of what? There ain't anything in that supply
>>>>that's several thousands...oops, my bad, there are some resistors that
>>>>are several thousands of ohms.
>>>>
>>> The supplies contain several thousands of volts, since the
>>>converters are of the flyback type (generally the most efficient type).
>>
>>PUT a sample of this particular supply on the bench, put a scope on it
>>and show me several thousand volts anywhere in it and I'll apologize
>>profusely.
>>Show me several thousand volts when it's unplugged and I'll eat
>>it...with the power on!
>>
>I've hesitated to come in, but you're quite right. The highest voltage
>you'll encounter is the supply voltage.

Well, actually the peak rectifed supply voltage, but otherwise correct.

>The reason why switched mode power supplies are not well understood -
>even in product R&D departments - is because most equipment
>manufacturers simply buy in the unit/module that they need. It's far
>more economic to do so.

I've designed them when I needed them on-board, but otherwise I'd always be
buying - whether in ones or hundreds.

>A good overview of switched mode power supplies (with explanations that
>most should understand) can be found at:
>
>http://en.wikipedia.org/wiki/Switched-mode_power_supply

"mike" <spamme9******.com> wrote in message
news:KjPmh.2206$Fs2.1884@trnddc05...
> M.I.5¾ wrote:
>> "mike" <spamme9******.com> wrote in message
>> news:Z6Mmh.1966$PN2.289@trnddc07...
>>
>>>M.I.5¾ wrote:
>>>
>>>><mc.preist******.com> wrote in message
>>>>news:1167770212.645064.150080@h40g2000cwb.goog legroups.com...
>>>>
>>>>
>>>>>I have a Dell Inspiron that comes with an 90W AC Adapter.
>>>>>It doesn't work and I need to open it. Does anyone know a nice way to
>>>>>open a Dell Adapter!?
>>>>>
>>>>
>>>>
>>>>Switch Mode Power Supplies (what you have) are very much a black art.
>>>
>>>Black art is the term you use when YOU don't understand something.
>>>Switching supplies are very much a known commodity.
>>>The problem is that the particular design is undocumented from the user
>>>point of view.
>>> The
>>>
>>>>chances of you repairing it are extremely slim at best.
>>>
>>>There you go again, projecting.
>>>Unless you really
>>>
>>>>know what you are doing, you are well advised to stay out of it.
>>>
>>> These
>>>
>>>>supplies contain internal voltages that can quite easily kill (several
>>>>thousands).
>>>
>>>kill several thousands of what? There ain't anything in that supply
>>>that's several thousands...oops, my bad, there are some resistors that
>>>are several thousands of ohms.
>>>
>>
>>
>> The supplies contain several thousands of volts, since the converters are
>> of the flyback type (generally the most efficient type).
>
> PUT a sample of this particular supply on the bench, put a scope on it
> and show me several thousand volts anywhere in it and I'll apologize
> profusely.
> Show me several thousand volts when it's unplugged and I'll eat it...with
> the power on!
>

The high voltage occurs across the primary of the high frequency converter
transformer. It is caused by by the rapidly collapsing magnetic field in
the core. The pulses are extremely short and require the 'scope time base
to be very rapid to see them. They contain more than sufficient energy to
cause heart seizure. You clearly have no idea of the modus operandi of
these devices.

> Power supplies of any type can be lethal whether plugged in or not.
> We agree on that. But plain wrong information undermines your
> credibility.
>

It is you that is undermining your credibility. I am a proffessional
engineer in the aerospace industry, so my credibility is already
established. When I fail to understand something, aeroplanes fall out of
the sky. This is something that does not impress my employer (and so far
has not happened (at least not that can be pinned on me)).

>>
>>
>>>Your conclusion is good for the average newbie...but if you want to
>>>support the conclusion, you should try to use some actual facts.
>>>
>>
>>
>> The fact that you may understand enough to repair them does not mean that
>> the average person does. Do you understand enough to design one from
>> scratch?
>
> Yes, in fact, I DO!! (your move)
> But in my experience, all you have to know is how to recognize a broken
> solder joint or an open/shorted cable. It's not rocket surgery.
> I rarely take it any farther than that. Because it's rarely necessary.
> Because it ceases to be fun after the first few reverse-engineering
> episodes.
>
> I understand them
>

You have alread proven that you don't.

> A claim unsupported so far.
>
> and I still say they are a black art to anyone
>> who does not specifically understand switch mode converters.
>
> Yes and auto mechanics is a black art to someone who knows nothing
> about auto mechanics and doesn't take the initiative to learn...so what?
> You do not have to be an engine designer to change a flat or the oil or
> put gas in it.

>>
>> You could do with working on your posting style.
>
> Criticism helps us improve.
> top posting?
> bottom posting?
> interleaved posting?
> too many caps?
> Bad grammar?
> Spelling?
> What?
> Or are you just pissed.
> Please be specific.

A style of abuse of other posters will just get you kill filed (though to be
fair, you seem to have recovered in this post).

>>
>>
> Since this has degenerated and the problem appears to have been
> discovered, allow me to answer the original question.
> Take the power brick and clamp it in a vise with the glue line just above
> the jaws.
> Start at one corner with a wood chisel. Give it a sharp whack with a
> small hammer to crack the joint. Move along the seam to propagate the
> crack.
> Don't pry on the seam. The plastic will tear before the glue comes loose.
> You have to use sharp broadside blows to fracture the joint. Quick whacks
> with a small hammer. NOT big swings with a sledge
>
> To put it back together, I use the glue they use on plastic water pipe.
> Comes in several types. I use the universal stuff.
>
> If you decide to try to fix it, find a computer hardware geek with a
> soldering iron to help you. Typical voltage inside one of these
> is 160 or 320 volts (for 120VAC USA applications. Could be twice
> that for 220/240VAC applications) depending on the design. And it can
> stay there
> for a long time after you unplug it. And yes, it can kill you.
>

You omitted (because you clearly don't know about it) the stored energy in
the inductive primary circuit of the converter transformer. Although this
is only present while the converter is running, it is several thousand volts
in amplitude (see above). It is this feature that allows power supplies to
be built that have very small sizes as the transformers give several volts
per turn on the secondary windings and these flyback pulses contain a lot of
energy despite their short duration. The basic principle of operation is
very similar to the line output stage of a television set doubling up as a
power supply. 5 to 10 volts per turn is not uncommon. This can never be
achieved by conventional operation of a transformer of the size in use where
20-30 *turns per volt* (note the inversion) would be more typical. The term
'Switch Mode Power Supply' is a little misleading in this regard as the term
really applies to the method by which voltage regulation is achieved.

I have a modified PC power supply here where we required a 10kV output for a
small CRT display. We got this simply by picking off the primary pulses and
rectifying them, then to a voltage doubler to give the 10kV. They really
are there.

> Cut a couple of inches off the cable and resolder it back into the
> board. Remember that if you get mixed up and put the wires back
> backwards, you risk turning your laptop into a doorstop. A smoking
> doorstop.
>

Nothing wrong with that - if that is what is wrong.

"Tony Morgan" <Tony@rhylonline.com> wrote in message
news:OWcX0HEYW9mFFwOc@axxc27.dsl.pipex.com...
> In message <KjPmh.2206$Fs2.1884@trnddc05>, mike <spamme9******.com> writes
>>M.I.5¾ wrote:
>>> "mike" <spamme9******.com> wrote in message
>>> news:Z6Mmh.1966$PN2.289@trnddc07...
>>>
>>>>M.I.5¾ wrote:
>>>>
>>>>><mc.preist******.com> wrote in message
>>>>>news:1167770212.645064.150080@h40g2000cwb.goo glegroups.com...
>>>>>
>>>>>
>>>>>>I have a Dell Inspiron that comes with an 90W AC Adapter.
>>>>>>It doesn't work and I need to open it. Does anyone know a nice way to
>>>>>>open a Dell Adapter!?
>>>>>>
>>>>>
>>>>>
>>>>>Switch Mode Power Supplies (what you have) are very much a black art.
>>>>
>>>>Black art is the term you use when YOU don't understand something.
>>>>Switching supplies are very much a known commodity.
>>>>The problem is that the particular design is undocumented from the user
>>>>point of view.
>>>> The
>>>>
>>>>>chances of you repairing it are extremely slim at best.
>>>>
>>>>There you go again, projecting.
>>>>Unless you really
>>>>
>>>>>know what you are doing, you are well advised to stay out of it.
>>>>
>>>> These
>>>>
>>>>>supplies contain internal voltages that can quite easily kill (several
>>>>>thousands).
>>>>
>>>>kill several thousands of what? There ain't anything in that supply
>>>>that's several thousands...oops, my bad, there are some resistors that
>>>>are several thousands of ohms.
>>>>
>>> The supplies contain several thousands of volts, since the converters
>>> are of the flyback type (generally the most efficient type).
>>
>>PUT a sample of this particular supply on the bench, put a scope on it
>>and show me several thousand volts anywhere in it and I'll apologize
>>profusely.
>>Show me several thousand volts when it's unplugged and I'll eat it...with
>>the power on!
>>
> I've hesitated to come in, but you're quite right. The highest voltage
> you'll encounter is the supply voltage.
>
> The reason why switched mode power supplies are not well understood - even
> in product R&D departments - is because most equipment manufacturers
> simply buy in the unit/module that they need. It's far more economic to do
> so.
>
> A good overview of switched mode power supplies (with explanations that
> most should understand) can be found at:
>
> http://en.wikipedia.org/wiki/Switched-mode_power_supply
>

An apparently over complicated article, because it not only covers switch
mode regulation but includes other parts of the supply not directly
associated with switch mode regulation. However, I can forgive it becasue
it tries to explain what most people understand as a Switch Mode Power
Supply (which is reasonable given the context). However, it describes a
standard type of power supply which in fact is rarely encountered these
days. It completely fails to mention the flyback mode of operation which is
the de facto method.

Somewhere downstairs, I have a very old, very early Switch Mode Supply (for
8008 microprocesor based system). Its output current is a fraction of what
computer supplies can provide today (about 15 Amp from the 5 volt output
IIRC). However, it is an early Switch Mode unit and definitely *not* of the
flyback type. I can't be bothered to go and measure it, but it is certainly
at least a foot square. The transformer, though not directly energised from
the mains is nevertheless quite large (and heavy). It was the introduction
of flyback mode converters that enabled the transformer to become a fraction
of the size.

M.I.5¾ wrote:
> "mike" <spamme9******.com> wrote in message
> news:KjPmh.2206$Fs2.1884@trnddc05...
>
>>M.I.5¾ wrote:
>>
>>>"mike" <spamme9******.com> wrote in message
>>>news:Z6Mmh.1966$PN2.289@trnddc07...
>>>
>>>
>>>>M.I.5¾ wrote:
>>>>
>>>>
>>>>><mc.preist******.com> wrote in message
>>>>>news:1167770212.645064.150080@h40g2000cwb.goo glegroups.com...
>>>>>
>>>>>
>>>>>
>>>>>>I have a Dell Inspiron that comes with an 90W AC Adapter.
>>>>>>It doesn't work and I need to open it. Does anyone know a nice way to
>>>>>>open a Dell Adapter!?
>>>>>>
>>>>>
>>>>>
>>>>>Switch Mode Power Supplies (what you have) are very much a black art.
>>>>
>>>>Black art is the term you use when YOU don't understand something.
>>>>Switching supplies are very much a known commodity.
>>>>The problem is that the particular design is undocumented from the user
>>>>point of view.
>>>> The
>>>>
>>>>
>>>>>chances of you repairing it are extremely slim at best.
>>>>
>>>>There you go again, projecting.
>>>>Unless you really
>>>>
>>>>
>>>>>know what you are doing, you are well advised to stay out of it.
>>>>
>>>> These
>>>>
>>>>
>>>>>supplies contain internal voltages that can quite easily kill (several
>>>>>thousands).
>>>>
>>>>kill several thousands of what? There ain't anything in that supply
>>>>that's several thousands...oops, my bad, there are some resistors that
>>>>are several thousands of ohms.
>>>>
>>>
>>>
>>>The supplies contain several thousands of volts, since the converters are
>>>of the flyback type (generally the most efficient type).
>>
>>PUT a sample of this particular supply on the bench, put a scope on it
>>and show me several thousand volts anywhere in it and I'll apologize
>>profusely.
>>Show me several thousand volts when it's unplugged and I'll eat it...with
>>the power on!
>>
>
>
> The high voltage occurs across the primary of the high frequency converter
> transformer. It is caused by by the rapidly collapsing magnetic field in
> the core. The pulses are extremely short and require the 'scope time base
> to be very rapid to see them. They contain more than sufficient energy to
> cause heart seizure. You clearly have no idea of the modus operandi of
> these devices.

Clearly???
>
You're absolutely correct in the general case. And it's easy to design
a supply that has "sereral thousands" of volts on the primary...assuming
you're willing to pay for the multi-kilovolt devices to drive it.
Most of us would elect to use cheap low-voltage drivers and let the
transformer do the work.
You only have to snub the leakage inductance.
Do some research on the concept of "snubbers".

My challenge stands. Take the PARTICULAR DELL LAPTOP supply in question
and show me multi-kilovolts anywhere in it on a real oscilloscope.

All my Dell supplies are 70W, so cracking one of them and publishing
the waveforms probably wouldn't satisfy you. You'll have to make the
measurement yourself.
>
>>Power supplies of any type can be lethal whether plugged in or not.
>>We agree on that. But plain wrong information undermines your
>>credibility.
>>
>
>
> It is you that is undermining your credibility. I am a proffessional
> engineer in the aerospace industry, so my credibility is already
> established.

It's been my experience that when engineers start telling me about their
credentials instead of repairing a flawed argument, the project is in
trouble.


When I fail to understand something, aeroplanes fall out of
> the sky.

OMG

This is something that does not impress my employer (and so far
> has not happened (at least not that can be pinned on me)).
>
>
>>>
>>>>Your conclusion is good for the average newbie...but if you want to
>>>>support the conclusion, you should try to use some actual facts.
>>>>
>>>
>>>
>>>The fact that you may understand enough to repair them does not mean that
>>>the average person does. Do you understand enough to design one from
>>>scratch?
>>
>>Yes, in fact, I DO!! (your move)
>>But in my experience, all you have to know is how to recognize a broken
>>solder joint or an open/shorted cable. It's not rocket surgery.
>>I rarely take it any farther than that. Because it's rarely necessary.
>>Because it ceases to be fun after the first few reverse-engineering
>>episodes.
>>
>>I understand them
>>
>
>
> You have alread proven that you don't.
>
>
>>A claim unsupported so far.
>>
>> and I still say they are a black art to anyone
>>
>>>who does not specifically understand switch mode converters.
>>
>>Yes and auto mechanics is a black art to someone who knows nothing
>>about auto mechanics and doesn't take the initiative to learn...so what?
>>You do not have to be an engine designer to change a flat or the oil or
>>put gas in it.
>
>
>>>You could do with working on your posting style.
>>
>>Criticism helps us improve.
>>top posting?
>>bottom posting?
>>interleaved posting?
>>too many caps?
>>Bad grammar?
>>Spelling?
>>What?
>>Or are you just pissed.
>>Please be specific.
>
>
> A style of abuse of other posters will just get you kill filed (though to be
> fair, you seem to have recovered in this post).
>
>
>>>
>>Since this has degenerated and the problem appears to have been
>>discovered, allow me to answer the original question.
>>Take the power brick and clamp it in a vise with the glue line just above
>>the jaws.
>>Start at one corner with a wood chisel. Give it a sharp whack with a
>>small hammer to crack the joint. Move along the seam to propagate the
>>crack.
>>Don't pry on the seam. The plastic will tear before the glue comes loose.
>>You have to use sharp broadside blows to fracture the joint. Quick whacks
>>with a small hammer. NOT big swings with a sledge
>>
>>To put it back together, I use the glue they use on plastic water pipe.
>>Comes in several types. I use the universal stuff.
>>
>>If you decide to try to fix it, find a computer hardware geek with a
>>soldering iron to help you. Typical voltage inside one of these
>>is 160 or 320 volts (for 120VAC USA applications. Could be twice
>>that for 220/240VAC applications) depending on the design. And it can
>>stay there
>>for a long time after you unplug it. And yes, it can kill you.
>>
>
>
> You omitted (because you clearly don't know about it)

Clearly??

the stored energy in
> the inductive primary circuit of the converter transformer. Although this
> is only present while the converter is running, it is several thousand volts
> in amplitude (see above).

My challenge stands...see above.

It is this feature that allows power supplies to
> be built that have very small sizes as the transformers give several volts
> per turn on the secondary windings and these flyback pulses contain a lot of
> energy despite their short duration.

Yes, you can certainly design supplies to do this. But they don't for
Dell laptop supplies.

The basic principle of operation is
> very similar to the line output stage of a television set doubling up as a
> power supply. 5 to 10 volts per turn is not uncommon. This can never be
> achieved by conventional operation of a transformer of the size in use where
> 20-30 *turns per volt* (note the inversion) would be more typical. The term
> 'Switch Mode Power Supply' is a little misleading in this regard as the term
> really applies to the method by which voltage regulation is achieved.
>
> I have a modified PC power supply here where we required a 10kV output for a
> small CRT display. We got this simply by picking off the primary pulses and
> rectifying them, then to a voltage doubler to give the 10kV. They really
> are there.

You're saying that you have a PC power supply that has driver FET's
with breakdown voltage OVER 5KV???? I want some of those FET's.

>
>
>>Cut a couple of inches off the cable and resolder it back into the
>>board. Remember that if you get mixed up and put the wires back
>>backwards, you risk turning your laptop into a doorstop. A smoking
>>doorstop.
>>
>
>
> Nothing wrong with that - if that is what is wrong.
>
>

"mike" <spamme9******.com> wrote in message
news:Rd5nh.21598$Ap5.13020@trnddc04...
> M.I.5¾ wrote:
>> "mike" <spamme9******.com> wrote in message
>> news:KjPmh.2206$Fs2.1884@trnddc05...
>>
>>>M.I.5¾ wrote:
>>>
>>>>"mike" <spamme9******.com> wrote in message
>>>>news:Z6Mmh.1966$PN2.289@trnddc07...
>>>>
>>>>
>>>>>M.I.5¾ wrote:
>>>>>
>>>>>
>>>>>><mc.preist******.com> wrote in message
>>>>>>news:1167770212.645064.150080@h40g2000cwb.go oglegroups.com...
>>>>>>
>>>>>>
>>>>>>
>>>>>>>I have a Dell Inspiron that comes with an 90W AC Adapter.
>>>>>>>It doesn't work and I need to open it. Does anyone know a nice way to
>>>>>>>open a Dell Adapter!?
>>>>>>>
>>>>>>
>>>>>>
>>>>>>Switch Mode Power Supplies (what you have) are very much a black art.
>>>>>
>>>>>Black art is the term you use when YOU don't understand something.
>>>>>Switching supplies are very much a known commodity.
>>>>>The problem is that the particular design is undocumented from the user
>>>>>point of view.
>>>>> The
>>>>>
>>>>>
>>>>>>chances of you repairing it are extremely slim at best.
>>>>>
>>>>>There you go again, projecting.
>>>>>Unless you really
>>>>>
>>>>>
>>>>>>know what you are doing, you are well advised to stay out of it.
>>>>>
>>>>> These
>>>>>
>>>>>
>>>>>>supplies contain internal voltages that can quite easily kill (several
>>>>>>thousands).
>>>>>
>>>>>kill several thousands of what? There ain't anything in that supply
>>>>>that's several thousands...oops, my bad, there are some resistors that
>>>>>are several thousands of ohms.
>>>>>
>>>>
>>>>
>>>>The supplies contain several thousands of volts, since the converters
>>>>are of the flyback type (generally the most efficient type).
>>>
>>>PUT a sample of this particular supply on the bench, put a scope on it
>>>and show me several thousand volts anywhere in it and I'll apologize
>>>profusely.
>>>Show me several thousand volts when it's unplugged and I'll eat it...with
>>>the power on!
>>>
>>
>>
>> The high voltage occurs across the primary of the high frequency
>> converter transformer. It is caused by by the rapidly collapsing
>> magnetic field in the core. The pulses are extremely short and require
>> the 'scope time base to be very rapid to see them. They contain more
>> than sufficient energy to cause heart seizure. You clearly have no idea
>> of the modus operandi of these devices.
>
> Clearly???
>>
> You're absolutely correct in the general case. And it's easy to design
> a supply that has "sereral thousands" of volts on the primary...assuming
> you're willing to pay for the multi-kilovolt devices to drive it.
> Most of us would elect to use cheap low-voltage drivers and let the
> transformer do the work.
> You only have to snub the leakage inductance.
> Do some research on the concept of "snubbers".
>
> My challenge stands. Take the PARTICULAR DELL LAPTOP supply in question
> and show me multi-kilovolts anywhere in it on a real oscilloscope.
>

I can lead you to water, but if you refuse to drink, that's not my problem.

> All my Dell supplies are 70W, so cracking one of them and publishing
> the waveforms probably wouldn't satisfy you. You'll have to make the
> measurement yourself.
>>
>>>Power supplies of any type can be lethal whether plugged in or not.
>>>We agree on that. But plain wrong information undermines your
>>>credibility.
>>>
>>
>>
>> It is you that is undermining your credibility. I am a proffessional
>> engineer in the aerospace industry, so my credibility is already
>> established.
>
> It's been my experience that when engineers start telling me about their
> credentials instead of repairing a flawed argument, the project is in
> trouble.
>

Your choice sunshine.

>
> When I fail to understand something, aeroplanes fall out of
>> the sky.
>
> OMG
>
> This is something that does not impress my employer (and so far
>> has not happened (at least not that can be pinned on me)).
>>
>>
>>>>
>>>>>Your conclusion is good for the average newbie...but if you want to
>>>>>support the conclusion, you should try to use some actual facts.
>>>>>
>>>>
>>>>
>>>>The fact that you may understand enough to repair them does not mean
>>>>that the average person does. Do you understand enough to design one
>>>>from scratch?
>>>
>>>Yes, in fact, I DO!! (your move)
>>>But in my experience, all you have to know is how to recognize a broken
>>>solder joint or an open/shorted cable. It's not rocket surgery.
>>>I rarely take it any farther than that. Because it's rarely necessary.
>>>Because it ceases to be fun after the first few reverse-engineering
>>>episodes.
>>>
>>>I understand them
>>>
>>
>>
>> You have alread proven that you don't.
>>
>>
>>>A claim unsupported so far.
>>>
>>> and I still say they are a black art to anyone
>>>
>>>>who does not specifically understand switch mode converters.
>>>
>>>Yes and auto mechanics is a black art to someone who knows nothing
>>>about auto mechanics and doesn't take the initiative to learn...so what?
>>>You do not have to be an engine designer to change a flat or the oil or
>>>put gas in it.
>>
>>
>>>>You could do with working on your posting style.
>>>
>>>Criticism helps us improve.
>>>top posting?
>>>bottom posting?
>>>interleaved posting?
>>>too many caps?
>>>Bad grammar?
>>>Spelling?
>>>What?
>>>Or are you just pissed.
>>>Please be specific.
>>
>>
>> A style of abuse of other posters will just get you kill filed (though to
>> be fair, you seem to have recovered in this post).
>>
>>
>>>>
>>>Since this has degenerated and the problem appears to have been
>>>discovered, allow me to answer the original question.
>>>Take the power brick and clamp it in a vise with the glue line just above
>>>the jaws.
>>>Start at one corner with a wood chisel. Give it a sharp whack with a
>>>small hammer to crack the joint. Move along the seam to propagate the
>>>crack.
>>>Don't pry on the seam. The plastic will tear before the glue comes
>>>loose. You have to use sharp broadside blows to fracture the joint. Quick
>>>whacks with a small hammer. NOT big swings with a sledge
>>>
>>>To put it back together, I use the glue they use on plastic water pipe.
>>>Comes in several types. I use the universal stuff.
>>>
>>>If you decide to try to fix it, find a computer hardware geek with a
>>>soldering iron to help you. Typical voltage inside one of these
>>>is 160 or 320 volts (for 120VAC USA applications. Could be twice
>>>that for 220/240VAC applications) depending on the design. And it can
>>>stay there
>>>for a long time after you unplug it. And yes, it can kill you.
>>>
>>
>>
>> You omitted (because you clearly don't know about it)
>
> Clearly??
>
> the stored energy in
>> the inductive primary circuit of the converter transformer. Although
>> this is only present while the converter is running, it is several
>> thousand volts in amplitude (see above).
>
> My challenge stands...see above.
>

and you are going to see it from there are you?

> It is this feature that allows power supplies to
>> be built that have very small sizes as the transformers give several
>> volts per turn on the secondary windings and these flyback pulses contain
>> a lot of energy despite their short duration.
>
> Yes, you can certainly design supplies to do this. But they don't for
> Dell laptop supplies.
>

They they would be ****ing big supplies then.

> The basic principle of operation is
>> very similar to the line output stage of a television set doubling up as
>> a power supply. 5 to 10 volts per turn is not uncommon. This can never
>> be achieved by conventional operation of a transformer of the size in use
>> where 20-30 *turns per volt* (note the inversion) would be more typical.
>> The term 'Switch Mode Power Supply' is a little misleading in this regard
>> as the term really applies to the method by which voltage regulation is
>> achieved.
>>
>> I have a modified PC power supply here where we required a 10kV output
>> for a small CRT display. We got this simply by picking off the primary
>> pulses and rectifying them, then to a voltage doubler to give the 10kV.
>> They really are there.
>
> You're saying that you have a PC power supply that has driver FET's
> with breakdown voltage OVER 5KV???? I want some of those FET's.
>

Thus demonstrating even greater ignorance. Of course the driver FETs don't
have to withstand the voltage. Ever heard of commutation? Thought not.

I get students fresh out of university who think they know everything, and
it is first necessary to rid them of that illusion. You sound exactly like
one.

Your posting style has me once again pissed me off, so I shall just resort
to killfilling you and ending the discussion here.

Tis done.

M.I.5¾ wrote:
> "mike" <spamme9******.com> wrote in message
> news:Rd5nh.21598$Ap5.13020@trnddc04...
>
>>M.I.5¾ wrote:
>>
>>>"mike" <spamme9******.com> wrote in message
>>>news:KjPmh.2206$Fs2.1884@trnddc05...
>>>
>>>
>>>>M.I.5¾ wrote:
>>>>
>>>>
>>>>>"mike" <spamme9******.com> wrote in message
>>>>>news:Z6Mmh.1966$PN2.289@trnddc07...
>>>>>
>>>>>
>>>>>
>>>>>>M.I.5¾ wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>><mc.preist******.com> wrote in message
>>>>>>>news:1167770212.645064.150080@h40g2000cwb.g ooglegroups.com...
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>I have a Dell Inspiron that comes with an 90W AC Adapter.
>>>>>>>>It doesn't work and I need to open it. Does anyone know a nice way to
>>>>>>>>open a Dell Adapter!?
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>Switch Mode Power Supplies (what you have) are very much a black art.
>>>>>>
>>>>>>Black art is the term you use when YOU don't understand something.
>>>>>>Switching supplies are very much a known commodity.
>>>>>>The problem is that the particular design is undocumented from the user
>>>>>>point of view.
>>>>>>The
>>>>>>
>>>>>>
>>>>>>
>>>>>>>chances of you repairing it are extremely slim at best.
>>>>>>
>>>>>>There you go again, projecting.
>>>>>>Unless you really
>>>>>>
>>>>>>
>>>>>>
>>>>>>>know what you are doing, you are well advised to stay out of it.
>>>>>>
>>>>>>These
>>>>>>
>>>>>>
>>>>>>
>>>>>>>supplies contain internal voltages that can quite easily kill (several
>>>>>>>thousands).
>>>>>>
>>>>>>kill several thousands of what? There ain't anything in that supply
>>>>>>that's several thousands...oops, my bad, there are some resistors that
>>>>>>are several thousands of ohms.
>>>>>>
>>>>>
>>>>>
>>>>>The supplies contain several thousands of volts, since the converters
>>>>>are of the flyback type (generally the most efficient type).
>>>>
>>>>PUT a sample of this particular supply on the bench, put a scope on it
>>>>and show me several thousand volts anywhere in it and I'll apologize
>>>>profusely.
>>>>Show me several thousand volts when it's unplugged and I'll eat it...with
>>>>the power on!
>>>>
>>>
>>>
>>>The high voltage occurs across the primary of the high frequency
>>>converter transformer. It is caused by by the rapidly collapsing
>>>magnetic field in the core. The pulses are extremely short and require
>>>the 'scope time base to be very rapid to see them. They contain more
>>>than sufficient energy to cause heart seizure. You clearly have no idea
>>>of the modus operandi of these devices.
>>
>>Clearly???
>>
>>You're absolutely correct in the general case. And it's easy to design
>>a supply that has "sereral thousands" of volts on the primary...assuming
>>you're willing to pay for the multi-kilovolt devices to drive it.
>>Most of us would elect to use cheap low-voltage drivers and let the
>>transformer do the work.
>>You only have to snub the leakage inductance.
>>Do some research on the concept of "snubbers".
>>
>>My challenge stands. Take the PARTICULAR DELL LAPTOP supply in question
>>and show me multi-kilovolts anywhere in it on a real oscilloscope.
>>
>
>
> I can lead you to water, but if you refuse to drink, that's not my problem.
>
>
>>All my Dell supplies are 70W, so cracking one of them and publishing
>>the waveforms probably wouldn't satisfy you. You'll have to make the
>>measurement yourself.
>>
>>>>Power supplies of any type can be lethal whether plugged in or not.
>>>>We agree on that. But plain wrong information undermines your
>>>>credibility.
>>>>
>>>
>>>
>>>It is you that is undermining your credibility. I am a proffessional
>>>engineer in the aerospace industry, so my credibility is already
>>>established.
>>
>>It's been my experience that when engineers start telling me about their
>>credentials instead of repairing a flawed argument, the project is in
>>trouble.
>>
>
>
> Your choice sunshine.
>
>
>>When I fail to understand something, aeroplanes fall out of
>>
>>>the sky.
>>
>>OMG
>>
>>This is something that does not impress my employer (and so far
>>
>>>has not happened (at least not that can be pinned on me)).
>>>
>>>
>>>
>>>>>>Your conclusion is good for the average newbie...but if you want to
>>>>>>support the conclusion, you should try to use some actual facts.
>>>>>>
>>>>>
>>>>>
>>>>>The fact that you may understand enough to repair them does not mean
>>>>>that the average person does. Do you understand enough to design one
>>>>
>>>>>from scratch?
>>>>
>>>>Yes, in fact, I DO!! (your move)
>>>>But in my experience, all you have to know is how to recognize a broken
>>>>solder joint or an open/shorted cable. It's not rocket surgery.
>>>>I rarely take it any farther than that. Because it's rarely necessary.
>>>>Because it ceases to be fun after the first few reverse-engineering
>>>>episodes.
>>>>
>>>>I understand them
>>>>
>>>
>>>
>>>You have alread proven that you don't.
>>>
>>>
>>>
>>>>A claim unsupported so far.
>>>>
>>>>and I still say they are a black art to anyone
>>>>
>>>>
>>>>>who does not specifically understand switch mode converters.
>>>>
>>>>Yes and auto mechanics is a black art to someone who knows nothing
>>>>about auto mechanics and doesn't take the initiative to learn...so what?
>>>>You do not have to be an engine designer to change a flat or the oil or
>>>>put gas in it.
>>>
>>>
>>>>>You could do with working on your posting style.
>>>>
>>>>Criticism helps us improve.
>>>>top posting?
>>>>bottom posting?
>>>>interleaved posting?
>>>>too many caps?
>>>>Bad grammar?
>>>>Spelling?
>>>>What?
>>>>Or are you just pissed.
>>>>Please be specific.
>>>
>>>
>>>A style of abuse of other posters will just get you kill filed (though to
>>>be fair, you seem to have recovered in this post).
>>>
>>>
>>>
>>>>Since this has degenerated and the problem appears to have been
>>>>discovered, allow me to answer the original question.
>>>>Take the power brick and clamp it in a vise with the glue line just above
>>>>the jaws.
>>>>Start at one corner with a wood chisel. Give it a sharp whack with a
>>>>small hammer to crack the joint. Move along the seam to propagate the
>>>>crack.
>>>>Don't pry on the seam. The plastic will tear before the glue comes
>>>>loose. You have to use sharp broadside blows to fracture the joint. Quick
>>>>whacks with a small hammer. NOT big swings with a sledge
>>>>
>>>>To put it back together, I use the glue they use on plastic water pipe.
>>>>Comes in several types. I use the universal stuff.
>>>>
>>>>If you decide to try to fix it, find a computer hardware geek with a
>>>>soldering iron to help you. Typical voltage inside one of these
>>>>is 160 or 320 volts (for 120VAC USA applications. Could be twice
>>>>that for 220/240VAC applications) depending on the design. And it can
>>>>stay there
>>>>for a long time after you unplug it. And yes, it can kill you.
>>>>
>>>
>>>
>>>You omitted (because you clearly don't know about it)
>>
>>Clearly??
>>
>>the stored energy in
>>
>>>the inductive primary circuit of the converter transformer. Although
>>>this is only present while the converter is running, it is several
>>>thousand volts in amplitude (see above).
>>
>>My challenge stands...see above.
>>
>
>
> and you are going to see it from there are you?

Nope, and you're not going to see it from THERE either.

>
>
>>It is this feature that allows power supplies to
>>
>>>be built that have very small sizes as the transformers give several
>>>volts per turn on the secondary windings and these flyback pulses contain
>>>a lot of energy despite their short duration.
>>
>>Yes, you can certainly design supplies to do this. But they don't for
>>Dell laptop supplies.
>>
>
>
> They they would be ****ing big supplies then.
>
>
>>The basic principle of operation is
>>
>>>very similar to the line output stage of a television set doubling up as
>>>a power supply. 5 to 10 volts per turn is not uncommon. This can never
>>>be achieved by conventional operation of a transformer of the size in use
>>>where 20-30 *turns per volt* (note the inversion) would be more typical.
>>>The term 'Switch Mode Power Supply' is a little misleading in this regard
>>>as the term really applies to the method by which voltage regulation is
>>>achieved.
>>>
>>>I have a modified PC power supply here where we required a 10kV output
>>>for a small CRT display. We got this simply by picking off the primary
>>>pulses and rectifying them, then to a voltage doubler to give the 10kV.
>>>They really are there.
>>
>>You're saying that you have a PC power supply that has driver FET's
>>with breakdown voltage OVER 5KV???? I want some of those FET's.
>>
>
>
> Thus demonstrating even greater ignorance. Of course the driver FETs don't
> have to withstand the voltage. Ever heard of commutation? Thought not.
>
> I get students fresh out of university who think they know everything, and
> it is first necessary to rid them of that illusion. You sound exactly like
> one.
>
> Your posting style has me once again pissed me off, so I shall just resort
> to killfilling you and ending the discussion here.
>
> Tis done.
But it has been fun!!!
Cheers.
>
>

I'm totally on the wrong mailing group :) LoL,
You're really into this guys.. respect!

I'm out :)..
going to my programming mailing lists!
Thanks a lot.

In message <B_6nh.5202$SQ1.2506@trnddc03>, mike <spamme9******.com>
writes
>But it has been fun!!!

Which tells me (and the thousands of other lurkers here )that you are
nothing more than a troll !

--
Tony Morgan

They are not intended to be opened and may well be truly sealed so that
they can't be non destructively opened, although I have successfully
opened some of them. Your chances of being able to fix it are small,
even if you do get it opened.


mc.preist******.com wrote:
> I have a Dell Inspiron that comes with an 90W AC Adapter.
> It doesn't work and I need to open it. Does anyone know a nice way to
> open a Dell Adapter!?
>
> Thank you in advanced!
> Igor.
>

Re: "These supplies contain internal voltages that can quite easily kill
(several thousands)"

The first part (voltages that can kill) is correct (which may in fact be
all that matters). But not anything even close to "several thousand".
In fact, nothing over 200 to about 400 volts. Still lethal, no
argument, but no where near even close to 1,000 volts.


M.I.5¾ wrote:
> <mc.preist******.com> wrote in message
> news:1167770212.645064.150080@h40g2000cwb.googlegr oups.com...
>> I have a Dell Inspiron that comes with an 90W AC Adapter.
>> It doesn't work and I need to open it. Does anyone know a nice way to
>> open a Dell Adapter!?
>>
>
> Switch Mode Power Supplies (what you have) are very much a black art. The
> chances of you repairing it are extremely slim at best. Unless you really
> know what you are doing, you are well advised to stay out of it. These
> supplies contain internal voltages that can quite easily kill (several
> thousands).
>
>

Re: "I've hesitated to come in, but you're quite right. The highest
voltage you'll encounter is the supply voltage."

That is actually not true. First, many switching power supplies run the
input voltage through a "voltage doubler" circuit using diodes and
capacitors. Second, the input voltage will be rectified and crudely
capacitor filtered, so you will see voltage near the peak value rather
than the RMS value. In other words, in a power supply operating off of
120 volts AC (which is an RMS value), the peak resulting DC value would
be about 120 x 1.414, or about 170 volts. Or, if the particular design
used a voltage-doubler input, you could see twice that (380 volts). And
if the input is 220/240 volts, you could potentially double those
numbers again.


Tony Morgan wrote:

>
> I've hesitated to come in, but you're quite right. The highest voltage
> you'll encounter is the supply voltage.
>
> The reason why switched mode power supplies are not well understood -
> even in product R&D departments - is because most equipment
> manufacturers simply buy in the unit/module that they need. It's far
> more economic to do so.
>
> A good overview of switched mode power supplies (with explanations that
> most should understand) can be found at:
>
> http://en.wikipedia.org/wiki/Switched-mode_power_supply
>
>

On Sat, 06 Jan 2007 21:39:26 -0500, Barry Watzman <WatzmanNOSPAM@neo.rr.com>
wrote:

>Re: "I've hesitated to come in, but you're quite right. The highest
>voltage you'll encounter is the supply voltage."
>
>That is actually not true. First, many switching power supplies run the
>input voltage through a "voltage doubler" circuit using diodes and
>capacitors. Second, the input voltage will be rectified and crudely
>capacitor filtered, so you will see voltage near the peak value rather
>than the RMS value. In other words, in a power supply operating off of
>120 volts AC (which is an RMS value), the peak resulting DC value would
>be about 120 x 1.414, or about 170 volts. Or, if the particular design
>used a voltage-doubler input, you could see twice that (380 volts). And
>if the input is 220/240 volts, you could potentially double those
>numbers again.

99 out of 100 Barry. The "normal" arrangement is to have the voltage doubling
in the 110/120 configuration but not in the 220/240 volt config. That gives the
DC in to the switcher pretty much the same voltage regardless of AC input volts.