sci.electronics.repair
http://groups.google.com/group/sci.electronics.repair?hl=en

sci.electronics.repair@googlegroups.com

Today's topics:

* Open SSID for HP printers - 4 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/2f0e2aeceb0c71fd?hl=en
* Request test jig suggestion for microUSB phone charging current - 2 messages,
2 authors
http://groups.google.com/group/sci.electronics.repair/t/d4fd3d1d8e105a63?hl=en
* Philips "Docking Entertainment System" Model DCM230, CD Player Issue - 2
messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/21f34ca4c0956864?hl=en
* Real RMS question - 10 messages, 6 authors
http://groups.google.com/group/sci.electronics.repair/t/c90e1a6c9dfca321?hl=en
* Test post for Termey - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/75f33cf051c5534b?hl=en
* Al madinah international university - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/e41d36878fe8e8c7?hl=en
* Sumvision SV 1000 recording DVD - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/e9cc608c8f3312a4?hl=en
* Are You Looking For Fridge Repair Service? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/67491ea6a7ce1fa6?hl=en

==============================================================================
TOPIC: Open SSID for HP printers
http://groups.google.com/group/sci.electronics.repair/t/2f0e2aeceb0c71fd?hl=en
==============================================================================

== 1 of 4 ==
Date: Sat, Jan 4 2014 12:48 pm
From: root


Michael Black <et472@ncf.ca> wrote:
> On Fri, 3 Jan 2014, root wrote:
>
>> I went walking around my neighborhood scanning for open wifi
>> hotspots and found several HP printers. Does that mean
>> that someone could park outside the place and a long stream
>> of documents to the printer(s)?
>>
>>
> Look on the bright side. They can't retrieve the printing unless they
> break into your house.
>
> Michael
>

I must not have made myself clear. I wonder whether a person
who has his printer setup as open could be victimized by
someone outside sending stuff to the open printer.

In my search for open sites I saw that some sites came
up as open and were HP printers. I don't know where they
are, they are just somewhere and open.





== 2 of 4 ==
Date: Sat, Jan 4 2014 2:33 pm
From: Leif Neland


root forklarede den 04-01-2014:
> Michael Black <et472@ncf.ca> wrote:
>> On Fri, 3 Jan 2014, root wrote:
>>
>>> I went walking around my neighborhood scanning for open wifi
>>> hotspots and found several HP printers. Does that mean
>>> that someone could park outside the place and a long stream
>>> of documents to the printer(s)?
>>>
>>>
>> Look on the bright side. They can't retrieve the printing unless they
>> break into your house.
>>
>> Michael
>>
>
> I must not have made myself clear. I wonder whether a person
> who has his printer setup as open could be victimized by
> someone outside sending stuff to the open printer.
>
I believe that's what the previous poster means.

They might be able to print on your printer, but they have to break
into your house to get the print.

But what they print could be X-rated, or they could just all your
toner/paper.

Perhaps it is possible to sneak malware to the printer, which could
send copies of the printed/scanned to a remote destination, or could
attack orher units on the local net.

I know of no such things however...

--
Husk k�relys bagp�, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.






== 3 of 4 ==
Date: Sat, Jan 4 2014 3:03 pm
From: mike


On 1/4/2014 2:33 PM, Leif Neland wrote:
> root forklarede den 04-01-2014:
>> Michael Black <et472@ncf.ca> wrote:
>>> On Fri, 3 Jan 2014, root wrote:
>>>
>>>> I went walking around my neighborhood scanning for open wifi
>>>> hotspots and found several HP printers. Does that mean
>>>> that someone could park outside the place and a long stream
>>>> of documents to the printer(s)?
>>>>
>>>>
>>> Look on the bright side. They can't retrieve the printing unless they
>>> break into your house.
>>>
>>> Michael
>>>
>>
>> I must not have made myself clear. I wonder whether a person
>> who has his printer setup as open could be victimized by
>> someone outside sending stuff to the open printer.
>>
> I believe that's what the previous poster means.
>
> They might be able to print on your printer, but they have to break into
> your house to get the print.
>
> But what they print could be X-rated, or they could just all your
> toner/paper.
>
> Perhaps it is possible to sneak malware to the printer, which could send
> copies of the printed/scanned to a remote destination, or could attack
> orher units on the local net.
>
> I know of no such things however...
>
check the name on the mailbox...
Hi, jim sent me by to pick up the printouts...




== 4 of 4 ==
Date: Sat, Jan 4 2014 3:39 pm
From: Fred McKenzie


In article <la9s2t$pg3$1@news.albasani.net>, root <NoEMail@home.org>
wrote:

> I must not have made myself clear. I wonder whether a person
> who has his printer setup as open could be victimized by
> someone outside sending stuff to the open printer.
>
> In my search for open sites I saw that some sites came
> up as open and were HP printers. I don't know where they
> are, they are just somewhere and open.

Root-

Obviously someone could do that. Damage might be limited by how much
paper is in the printer, or how quickly the owner could react if nearby.

Many wireless printers come with their WiFi set up in ad-hoc mode. HP
also has their "Wi-Fi Direct" mode. You can connect directly to them
unless they have been paired with a WiFi router.

I think what you are seeing are wireless printers that are either
connected by a USB cable instead of WiFi, or are being used with iPhones
that have their internet connection through the phone company.

The owners may not be aware that the printer's WiFi is open! Anyone
that has such a printer should at least set the WiFi to require a
password.

Fred





==============================================================================
TOPIC: Request test jig suggestion for microUSB phone charging current
http://groups.google.com/group/sci.electronics.repair/t/d4fd3d1d8e105a63?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, Jan 4 2014 3:02 pm
From: mike


On 1/4/2014 10:29 AM, mroberds@att.net wrote:
> Followups set to sci.electronics.repair .
>
> In sci.electronics.repair Danny D'Amico <danny@is.invalid> wrote:
>> How would you make a test jig out of a spare USB cable?
>
> With a sharp knife, remove 2 inches (50 mm) or so of the outer
> insulation of the cable, in the middle of the cable. Try hard not
> to nick the insulation on the four individual wires inside the cable,
> but if you do, it's not a total disaster.
>
> Next, try to identify the two data wires and the two power wires. Often
> the data wires will be twisted; the power wires may or may not be. The
> power wires will also often be one or two wire gauges thicker than the
> data wires, but not always, and this is kind of hard to tell. The power
> wires *might* be red and black, but don't count on this.
>
> Pick what you think is one of the power wires and cut it, right in the
> middle of the stripped part. Strip the cut wire ends 1/4" (6 mm) or so.
> Get your multimeter and test between all four contacts on the big (PC)
> end of the cable, and the stripped wire that comes from that connector.
> It may help to use a paper clip or other small piece of solid wire to
> touch the contacts in the USB connector if the multimeter probe won't
> fit.
>
> If the stripped wire is continuous with only one of the two outside
> contacts in the USB plug, you did indeed cut one of the power wires.
>
> If the stripped wire is continuous with only one of the two inside
> contacts (it doesn't matter which one), you picked a data wire; solder
> the stripped ends back together, insulate with a small amount of tape
> (electrical tape is ideal, Scotch tape will work fine for this), and
> pick another wire.
>
> If the stripped wire is continuous with more than one contact, then
> you probably nicked the insulation on more than one wire when you were
> initially stripping the cable - find the places that are touching and
> separate them, and maybe insulate the bare spots individually with
> tape.
>
> Once you have figured out that you did indeed cut the power wire, you
> can figure out how to hook the power wire up to your multimeter. Your
> meter may have come with alligator clips that go on the probe ends; if
> you have those, use them. What I use for things like this, because I
> already own some, are clip leads - short stranded wires with alligator
> clips on each end. Rat Shock 278-1157 or 278-1156 are typical; Fry's
> probably has a better price on similar products.
> http://www.radioshack.com/product/index.jsp?productId=2062661
> http://www.radioshack.com/product/index.jsp?productId=2062660
>
> If you have alligator clips that fit your meter probes, put them on the
> probes. If you have a digital meter, clip one probe to one stripped
> wire and the other probe to the other one - it does not matter which
> way around the red and black wires are. If you get the probes
> "backwards", you will get exactly the same current reading, just with
> a minus sign in front of it. If you have an analog meter, you have to
> get the probes the right way around, but IIRC you have a digital one.
>
> If you have clip leads, clip a red clip lead to the red probe of your
> meter and to one of the stripped wire ends. Clip a black clip lead
> to the black probe of your meter and to the other stripped wire again.
> As above, if you have a digital meter, it does not matter which way
> around the red and black wires are.
>
> Next, figure out how to make your multimeter measure current. With the
> meters most people have, you need to rotate a dial to an "A DC" range,
> and move the red meter lead over to a different jack on the meter. Do
> whatever you need to for your particular meter.
>
> Plug the mini-USB end into your peripheral (external hard drive or
> whatever). Put the peripheral somewhere close to the meter, so you can
> watch it and the meter at the same time. While watching both the
> peripheral and the meter, plug the PC end of the USB cable into the PC.
>
> If all is well, the peripheral should come on (hard drive spins up /
> LED comes on / whatever), and the meter should show some amount of
> current. If nothing is happening, or if you smell smoke, unplug the
> USB cable from the PC immediately and investigate. If the peripheral
> draws "too much" current, the PC may shut down that particular USB port;
> this isn't permanent, but sometimes it takes a reboot to re-enable the
> port.
>
> Don't be surprised if the current jumps around some as the device
> operates. Even "simple" stuff like keyboards will draw slightly
> different amounts of current when you are typing vs not, or when (say)
> the Caps Lock LED is on, or whatever. If your meter has a "max hold"
> or "peak hold" function, that can be useful to capture the highest
> current reading the meter sees. Some peripherals will have a current
> rating printed on them, but this is usually the maximum current it
> will ever draw - it won't usually draw that much continuously.
>
> When you are done measuring current with your multimeter, disconnect
> the leads from the circuit, and *IMMEDIATELY* move the red lead back
> over to its regular socket - don't wait until later to move it back.
> The reason is that in the amps range, the meter is nearly a dead short.
> It's *easy* to measure current and then try to measure voltage without
> moving the lead back, and blow the fuse in the meter. I've watched it
> being done and I've even done it myself.
>
> Standard disclaimers apply: I don't get money or other consideration
> from any companies mentioned.
>
> Matt Roberds
>
If I understand you, you're saying that it's ok to measure in the ground
wire.
In a perfect world, that's no problem...Assuming there isn't a shield
wire that bridges it.
Given all the things that can go wrong, I'd suggest you stick to
measuring in the +5 wire.
Breaking the ground never breaks anything...until it does.




== 2 of 2 ==
Date: Sun, Jan 5 2014 6:37 pm
From: mroberds@att.net


mike <ham789@netzero.net> wrote:
> On 1/4/2014 10:29 AM, mroberds@att.net wrote:
>>
>> Pick what you think is one of the power wires and cut it, right in
>> the middle of the stripped part.
>>
> If I understand you, you're saying that it's ok to measure in the
> ground wire.

That is what I was saying, yes.

> In a perfect world, that's no problem...Assuming there isn't a shield
> wire that bridges it.

The few USB devices I've taken apart seem to do a decent job of not
returning the power supply current on the shield, but I am aware that
there are millions of devices out there, and they probably don't all do
it the same way. (Hey, if we run the power supply ground on the shield,
we can use 3-wire cable instead of 4-wire and save 0.00013 cents per
unit!)

> Given all the things that can go wrong, I'd suggest you stick to
> measuring in the +5 wire.

I agree that that's generally a good plan. I figured that not being
picky about which power wire was opened would be easier to implement
for the original poster.

Matt Roberds






==============================================================================
TOPIC: Philips "Docking Entertainment System" Model DCM230, CD Player Issue
http://groups.google.com/group/sci.electronics.repair/t/21f34ca4c0956864?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, Jan 4 2014 4:49 pm
From: "Mark Zacharias"


<jaugustine@verizon.net> wrote in message
news:mssac9lvshhg04onu8146hrm7lkc2ctlpe@4ax.com...
> <SNIP>
>>
>>Philips laser pickups die like flies. Just sayin' .
>>
>>Some versions are available on eBay cheap.
>>
>>Mark Z.
>
> Hi Mark,
>
> Did you notice that I said the cd disc does not spin?
> Note: Not exact words.
>
> Before the pickup can do anything, the disc has to
> spin first.
>
> John
>


They must achieve focus before they will spin. This has been the case for 20
years.

mz





== 2 of 2 ==
Date: Sun, Jan 5 2014 1:31 am
From: Leif Neland


Mark Zacharias kom med denne ide:

>
> They [ cd player ] must achieve focus before they will spin. This has been
> the case for 20 years.
>

Probably to make sure the "pickup" is not resting solidly on the disk
or a chocolate biscuit.

Leif

--
Husk k�relys bagp�, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.







==============================================================================
TOPIC: Real RMS question
http://groups.google.com/group/sci.electronics.repair/t/c90e1a6c9dfca321?hl=en
==============================================================================

== 1 of 10 ==
Date: Sat, Jan 4 2014 5:28 pm
From: "Phil Allison"



"Leif Neland"
> Phil Allison
>> Same idea as using a glass of water and a thermometer test the power RF
>> power of a microwave oven.
>
> Just don't leave the thermometer in the microwave oven with the power on.

** Should be OK with a glass tube and red liquid type.


> Measure the temperature of the cold water, then measure the time for it to
> boil.

** Bad idea.

Takes far too long, when boiling first begins is not clear and lots of heat
is lost to the air and evaporation.


> I measured the power of my previous oven to 230W...

** Using half a litre in a plastic jug for two minutes, I got the answer to
within 10% with a 700W rated oven.

Having a K-type bead thermocouple and digital temp meter made the job easier
too.



.... Phil






== 2 of 10 ==
Date: Sat, Jan 4 2014 6:21 pm
From: "Shaun"




"Phil Allison" wrote in message news:birqprFai6pU1@mid.individual.net...


"Leif Neland"
> Phil Allison
>> Same idea as using a glass of water and a thermometer test the power RF
>> power of a microwave oven.
>
> Just don't leave the thermometer in the microwave oven with the power on.

>** Should be OK with a glass tube and red liquid type.


> Measure the temperature of the cold water, then measure the time for it to
> boil.

** Bad idea.

>Takes far too long, when boiling first begins is not clear and lots of heat
is lost to the air and evaporation.


> I measured the power of my previous oven to 230W...

>** Using half a litre in a plastic jug for two minutes, I got the answer to
within 10% with a 700W rated oven.

>Having a K-type bead thermocouple and digital temp meter made the job
>easier
too.

You don't run it till boiling! once you get close to boiling point a lot of
extra energy is required to raise it further and make it boil. What you do
is run a glass of cold distilled water measured (temp and volume) in a
container, you could use several stacked Styrofoam cups for insulation and
cover the top with Styrofoam so that the heat generated does not escape and
run the oven till the temperature increase 20 to 50 degrees or so, then
measure the temp, the information will have an equation to convert degrees
rise to microwave power. Google the method - I haven't looked it up lately.

Shaun



.... Phil





== 3 of 10 ==
Date: Sat, Jan 4 2014 6:29 pm
From: dave


On 01/04/2014 06:21 PM, Shaun wrote:
>
>
> "Phil Allison" wrote in message news:birqprFai6pU1@mid.individual.net...
>
>
> "Leif Neland"
>> Phil Allison
>>> Same idea as using a glass of water and a thermometer test the power
>>> RF power of a microwave oven.
>>
>> Just don't leave the thermometer in the microwave oven with the power on.
>
>> ** Should be OK with a glass tube and red liquid type.
>
>
>> Measure the temperature of the cold water, then measure the time for
>> it to boil.
>
> ** Bad idea.
>
>> Takes far too long, when boiling first begins is not clear and lots of
>> heat
> is lost to the air and evaporation.
>
>
>> I measured the power of my previous oven to 230W...
>
>> ** Using half a litre in a plastic jug for two minutes, I got the
>> answer to
> within 10% with a 700W rated oven.
>
>> Having a K-type bead thermocouple and digital temp meter made the job
>> easier
> too.
>
> You don't run it till boiling! once you get close to boiling point a
> lot of extra energy is required to raise it further and make it boil.
> What you do is run a glass of cold distilled water measured (temp and
> volume) in a container, you could use several stacked Styrofoam cups for
> insulation and cover the top with Styrofoam so that the heat generated
> does not escape and run the oven till the temperature increase 20 to 50
> degrees or so, then measure the temp, the information will have an
> equation to convert degrees rise to microwave power. Google the method
> - I haven't looked it up lately.
>
> Shaun
>
>
>
> .... Phil
>
That is not how a calorimeter works. The load must be enclosed in liquid
and must perfectly match the RF output so it absorbs all the energy.
Then the temperature should be a very accurate way to measure power. It
must be a closed, water cooled load.

http://electro-impulse.com/techinfo/calorimeters.htm




== 4 of 10 ==
Date: Sat, Jan 4 2014 6:41 pm
From: "Shaun"




"Shaun" wrote in message news:Pk3yu.184114$Ks5.25080@fx08.iad...



"Phil Allison" wrote in message news:birqprFai6pU1@mid.individual.net...


"Leif Neland"
> Phil Allison
>> Same idea as using a glass of water and a thermometer test the power RF
>> power of a microwave oven.
>
> Just don't leave the thermometer in the microwave oven with the power on.

>** Should be OK with a glass tube and red liquid type.


> Measure the temperature of the cold water, then measure the time for it to
> boil.

** Bad idea.

>Takes far too long, when boiling first begins is not clear and lots of heat
is lost to the air and evaporation.


> I measured the power of my previous oven to 230W...

>** Using half a litre in a plastic jug for two minutes, I got the answer to
within 10% with a 700W rated oven.

>Having a K-type bead thermocouple and digital temp meter made the job
>easier
too.

You don't run it till boiling! once you get close to boiling point a lot of
extra energy is required to raise it further and make it boil. What you do
is run a glass of cold distilled water measured (temp and volume) in a
container, you could use several stacked Styrofoam cups for insulation and
cover the top with Styrofoam so that the heat generated does not escape and
run the oven till the temperature increase 20 to 50 degrees or so, then
measure the temp, the information will have an equation to convert degrees
rise to microwave power. Google the method - I haven't looked it up lately.

Shaun



Here is the Method from RepairFAQ from Sam:



7.1) Testing the oven - the water heating test


The precise number of degrees a known quantity of water increases in
temperature for a known time and power level is a very accurate test of
the actual useful microwave power. A couple of minutes with a cup of
water and a thermometer will conclusively determine if your microwave
oven is weak or you are just less patient (or the manufacturer of your
frozen dinners has increased their weight - sure, fat chance of that!)

You can skip the heavy math below and jump right to the final result
if you like. However, for those who are interested:

* 1 Calorie (C) will raise the temperature of 1 gram (g) of liquid water
exactly 1 degree Centigrade (DegC) or 9/5 degree Fahrenheit (DegF).

* 1 Calorie is equal to 4.184 Joules (J) or 1 J = .239 C.

* 1 Watt (W) of power is 1 J/s or 1 KW is 1000 J/s.

* 1 cup is 8 ounces (oz) which is 8 x 28.35 g/oz = 226.8 g.

* 1 minute equals 60 s (but you know this!).

Therefore, in one minute, a 1 KW microwave oven will raise the temperature
of 1 cup of water by:

T(rise) = (60 s * 1000 J/s * .239C/J * (g * DegC)/C)/(226.8 g) = 63
DegC.

Or, if your prefer Fahrenheit: 114 DegF.

To account for estimated losses due to conduction, convection, and imperfect
power transfer, I suggest using temperature rises of 60 DegC and 109 DegF.

Therefore, a very simple test is to place a measured cup of water in the
microwave from the tap and measure its temperature before and after heating
for exactly 1 minute on HIGH. Scale the expected temperature rise by the
ratio of the microwave (not AC line) power of your oven compared to a 1 KW
unit.

Or, from a Litton microwave handbook:

Heat one Liter (L) of water on HIGH for 1 minute.

Oven power = temperature rise in DegC multiplied by 70.

Use a plastic container rather than a glass one to minimize the needed
energy loss to raise its temperature by conduction from the hot water.
There will be some losses due to convection but this should not be that
significant for these short tests.

(Note: if the water is boiling when it comes out - at 100 DegC or 212 DegF,
then the test is invalid - use colder water or a shorter time.)

The intermediate power levels can be tested as well. The heating effect of
a microwave oven is nearly linear. Thus, a cup of water should take nearly
roughly twice as long to heat a specific number of degrees on 50% power or
3.3 times as long on 30% power as on full power. However, for low power
tests, increasing the time to 2 minutes with 2 cups of water will result
in more accurate measurements due to the long period pulse width power
control use by microwave ovens which may have a cycle of up to 30 seconds.

Any significant discrepancy between your measurements and the specified
microwave power levels - say more than 10 % on HIGH - may indicate a
problem.
(Due to conduction and convection losses as well as the time required to
heat the filament of the magnetron for each on-cycle, the accuracies of
the intermediate power level measurements may be slightly lower).

Shaun







== 5 of 10 ==
Date: Sat, Jan 4 2014 11:53 pm
From: Jeff Urban


I wanted to reply to this when you first posted it but I couldn't for
whatever reason. fucking thing. As you can see I am not posting from
google, which I no longer capitalize !!!! LOL

Anyway, what characterizes ANY part for the transmission of audio is
linearity. Even though the gate of a MOSFET is driven wildly different
than the base of a BPT, linearity of gain fro the very small signal to
the very large signal is the prime. We used to look at the hfe and HFE
gain curves of bipolars in the old days, not it is different.

Any kinds of spurious shit like oscillations would be no good in
switcxhers as well. the thing is, switchers somethimes have a gain curve
that is like, made to be on or off.

An audio transistor must operate in the analog range, that means the
gain curve should be as flat as possible through the operating current
range.

The same is true of a MOSFET.





== 6 of 10 ==
Date: Sun, Jan 5 2014 12:24 am
From: N_Cook


On 05/01/2014 07:53, Jeff Urban wrote:
> I wanted to reply to this when you first posted it but I couldn't for
> whatever reason. fucking thing. As you can see I am not posting from
> google, which I no longer capitalize !!!! LOL
>
> Anyway, what characterizes ANY part for the transmission of audio is
> linearity. Even though the gate of a MOSFET is driven wildly different
> than the base of a BPT, linearity of gain fro the very small signal to
> the very large signal is the prime. We used to look at the hfe and HFE
> gain curves of bipolars in the old days, not it is different.
>
> Any kinds of spurious shit like oscillations would be no good in
> switcxhers as well. the thing is, switchers somethimes have a gain curve
> that is like, made to be on or off.
>
> An audio transistor must operate in the analog range, that means the
> gain curve should be as flat as possible through the operating current
> range.
>
> The same is true of a MOSFET.
>

Ah at last , thanks, a pertinent reply to my original question. I was
wondering if it was a larger area of silicon so the heat can migrate out
of the die quicker. So from what you say a non-audio switcher mosfet
could be used for analogue but the power rating would have to be derated
and no other qualification for such use, anymore than usual precautions
you would use for a switcher situation. I suppose the amount of derating
would then depend on the type of use bass amp v GP audio amp, dance
music v classical music etc




== 7 of 10 ==
Date: Sun, Jan 5 2014 3:06 am
From: "Phil Allison"



"Nutcase Kook is yet another pig ignorant pommy cunt"


> Other than p channel in this case, same for BUZ901P nch
> eg BUZ906P 200V, 8A ,datasheet says
> "POWER MOSFETS FOR
> AUDIO APPLICATIONS"
> but also
> "FEATURES ... (for use in)
> HIGH SPEED SWITCHING ... "


** The Semelab app note makes it pretty clear there is a HUGE difference
between "switching" and audio ( ie lateral) power mosfets.

http://products.semelab-tt.com/pdf/ApplicationNoteAlfet.pdf


> Would a powerFET designed solely for high speed switching use and 125W
> rating be derated in power handling terms to only 50W say for linear 10 Hz
> use. Or secondary oscillation liability if paralleled up devices? or some
> other operational failing in audio use not found with smps say ?

** Yawnnnnnnnnnnnnnnn....

More brainless, fucking TROLLING !!!!!!!

FOAD you vile pommy cunthead.



.... Phil


> Ah at last , thanks, a pertinent reply to my original question.


** There is no possible answer to a question as wrong headed and stupid as
that.

So you will never get one.

FOAD you vile pommy cunthead.




.... Phil













== 8 of 10 ==
Date: Sun, Jan 5 2014 3:29 am
From: N_Cook


On 05/01/2014 07:53, Jeff Urban wrote:
> I wanted to reply to this when you first posted it but I couldn't for
> whatever reason. fucking thing. As you can see I am not posting from
> google, which I no longer capitalize !!!! LOL
>
> Anyway, what characterizes ANY part for the transmission of audio is
> linearity. Even though the gate of a MOSFET is driven wildly different
> than the base of a BPT, linearity of gain fro the very small signal to
> the very large signal is the prime. We used to look at the hfe and HFE
> gain curves of bipolars in the old days, not it is different.
>
> Any kinds of spurious shit like oscillations would be no good in
> switcxhers as well. the thing is, switchers somethimes have a gain curve
> that is like, made to be on or off.
>
> An audio transistor must operate in the analog range, that means the
> gain curve should be as flat as possible through the operating current
> range.
>
> The same is true of a MOSFET.
>

or on rereading . If an audio application can tolerate a certain amount
of cross-over distortion and general harmonic distortion then there is
no difference in powerfet useage type , up to some power level where
these distortions become too apparent.




== 9 of 10 ==
Date: Sun, Jan 5 2014 5:50 pm
From: dave


On 01/05/2014 03:29 AM, N_Cook wrote:
> On 05/01/2014 07:53, Jeff Urban wrote:
>> I wanted to reply to this when you first posted it but I couldn't for
>> whatever reason. fucking thing. As you can see I am not posting from
>> google, which I no longer capitalize !!!! LOL
>>
>> Anyway, what characterizes ANY part for the transmission of audio is
>> linearity. Even though the gate of a MOSFET is driven wildly different
>> than the base of a BPT, linearity of gain fro the very small signal to
>> the very large signal is the prime. We used to look at the hfe and HFE
>> gain curves of bipolars in the old days, not it is different.
>>
>> Any kinds of spurious shit like oscillations would be no good in
>> switcxhers as well. the thing is, switchers somethimes have a gain curve
>> that is like, made to be on or off.
>>
>> An audio transistor must operate in the analog range, that means the
>> gain curve should be as flat as possible through the operating current
>> range.
>>
>> The same is true of a MOSFET.
>>
>
> or on rereading . If an audio application can tolerate a certain amount
> of cross-over distortion and general harmonic distortion then there is
> no difference in powerfet useage type , up to some power level where
> these distortions become too apparent.

I learned what I needed to know to rebuild a fried Ampeg SVT3Pro. 4 [ea]
irfp9240s 4 [ea] irfp240s. Will oscillate itself to death. Must use a
scope and a light bulb current limiter to detect sudden current surging
due to rf feeding back. I think Vishay has some linear application notes
for these MOSFETs. They can be biased for very tiny crossover notch, but
the spec is bias for 800ma at the AC mains with no signal. Not terribly
efficient. But it's a bass guitar amp.




== 10 of 10 ==
Date: Sun, Jan 5 2014 6:30 pm
From: mroberds@att.net


Shaun <stereobuff07@gmail.com> wrote:
> When I did similar tests, I found the order of magnitude was right,
> but the result depended on the shape and volume of the mass of water
> and position in the oven. [...]
>
> Wonder what the "official" water configuration is when they determine
> the spec?

I don't know about a US Federal Trade Commission (or other agency, or
equivalent in other countries) test procedure; there probably is one but
I don't know it.

I know that older GE microwave ovens, in the little service information
sheet that was folded up inside the oven, gave directions on the test, a
GE part number for a beaker you were supposed to use, and I think a
third-party part number for the thermometer you were supposed to use to
measure the water temperature before and after. I think the water level
was marked on the beaker, and the service sheet said to put it right in
the middle of the oven. You didn't boil it, just heated it for a fixed
amount of time.

If I remember right, the criteria was something like "if the oven
produced between X and Y degrees temperature rise in the water, it's
within spec" - it didn't give you an answer in watts, just an acceptable
temperature range for that particular model oven.

Matt Roberds






==============================================================================
TOPIC: Test post for Termey
http://groups.google.com/group/sci.electronics.repair/t/75f33cf051c5534b?hl=en
==============================================================================

== 1 of 3 ==
Date: Sat, Jan 4 2014 7:11 pm
From: Jeff Urban


Now I am using Thunderbird though aeio or whatever it is. When it works,
google works. When it doesn't work, neither does google.




== 2 of 3 ==
Date: Sat, Jan 4 2014 7:39 pm
From: John G


It happens that Jeff Urban formulated :
> Now I am using Thunderbird though aeio or whatever it is. When it works,
> google works. When it doesn't work, neither does google.

That would idicate to most people that your link to the world was down.
Either At your place or the connection company or the ISP?? B-)

--
John G




== 3 of 3 ==
Date: Sat, Jan 4 2014 11:46 pm
From: Jeff Urban


Sorry to be a pain. This thread will have to serve as my tester right
now until I find out what's going on.







==============================================================================
TOPIC: Al madinah international university
http://groups.google.com/group/sci.electronics.repair/t/e41d36878fe8e8c7?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jan 5 2014 4:49 am
From: marketing@mediu.ws


Al madinah international university

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The following colleges :

* Faculty of Islamic Sciences
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* Faculty of Computer and Information Technology.
*Faculty of education .
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*Language center
*Faculty of engineering

The university offer :
• Bachelor degree
• Master degree
• PHD degree
Both online and on campus learning for more information you can visit
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for more information about Bachelor degree
http://www.mediu.edu.my/ar/admissions/undergraduateprograms

for more information about master degree
http://www.mediu.edu.my/ar/admissions/postgraduateprograms


Best Regard
Al madinah international university

//www.mediu.edu.my/ar/





==============================================================================
TOPIC: Sumvision SV 1000 recording DVD
http://groups.google.com/group/sci.electronics.repair/t/e9cc608c8f3312a4?hl=en
==============================================================================

== 1 of 3 ==
Date: Sun, Jan 5 2014 2:24 pm
From: "Arfa Daily"




"N_Cook" <diverse@tcp.co.uk> wrote in message
news:la3dir$5hi$1@dont-email.me...
> Burnt and burst SMPS supervisor on this otherwise no-name and little
> chance Chinese thing. As laser and motor/s in the DVD deck and heatsink
> bonded to a video chip a reasonable power draw.
> But the SMPS IC , in a conventional 8 pin DIP package also contains the Tx
> driver transistor. So air gap under the IC and reverse side of pcb
> enlarged pad of pcb-copper as some sort of vain attempt at heatsink.
> Thermal connection to this is via just pins 4 and 5 combined in normal
> soldering , connected to the Tx. There is a hole through the pcb as though
> for some sort of clip to go perhaps top and bottom of the IC and bolted
> through to this under pad but no sign of anything having been fitted
> there, no deformation of the tinning over the pad around the hole. Turning
> over the unit and shaking over paper meant the blasted away top part ,
> mainly, of the IC emerged but no clip at all.
> Is it possible to have combined supervisor and driver transistor in an
> 8pin DIP package with no heatsink tab provision? or are there combined
> SMPS TX with internal driver transistor buried in the base?
> Also ps supply provision marked on pcb ac 85V - 250V
> IC logi i in a reversed D
> marked in 3 lines ICE 2?26 maybe more numbers, ? maybe a 4
> logo then 0 and more
> XK4.. probably more numbers
> probable pinning
> p1 0.1uF to 0V
> p2 to optocoupler
> p3 over current sense
> p4-p5 to Tx low side
> p6 n/c
> p7 supply <25V
> p8 0V
>

SMPS controller ICs with the letters "ICE" as the first part of their type
number are quite common. Such ICs are often coupled directly to a power FET
switching element, but are just as commonly connected directly to a small
SMPS Tx, particularly when it is a standby supply. I have always been amazed
that these chips can stand the better part of 400 volts across their
internal FET, and that it can supply enough current to drive the Tx
directly. I guess the thermal issues are dictated by how good the RDSon of
the internal device is. The closer it is to zero ohms, the lower the
dissipation, and some these days are pretty damn close to zero for all
practical purposes.

Arfa





== 2 of 3 ==
Date: Mon, Jan 6 2014 12:32 am
From: N_Cook


On 05/01/2014 22:24, Arfa Daily wrote:
>
>
> "N_Cook" <diverse@tcp.co.uk> wrote in message
> news:la3dir$5hi$1@dont-email.me...
>> Burnt and burst SMPS supervisor on this otherwise no-name and little
>> chance Chinese thing. As laser and motor/s in the DVD deck and
>> heatsink bonded to a video chip a reasonable power draw.
>> But the SMPS IC , in a conventional 8 pin DIP package also contains
>> the Tx driver transistor. So air gap under the IC and reverse side of
>> pcb enlarged pad of pcb-copper as some sort of vain attempt at
>> heatsink. Thermal connection to this is via just pins 4 and 5 combined
>> in normal soldering , connected to the Tx. There is a hole through the
>> pcb as though for some sort of clip to go perhaps top and bottom of
>> the IC and bolted through to this under pad but no sign of anything
>> having been fitted there, no deformation of the tinning over the pad
>> around the hole. Turning over the unit and shaking over paper meant
>> the blasted away top part , mainly, of the IC emerged but no clip at all.
>> Is it possible to have combined supervisor and driver transistor in an
>> 8pin DIP package with no heatsink tab provision? or are there combined
>> SMPS TX with internal driver transistor buried in the base?
>> Also ps supply provision marked on pcb ac 85V - 250V
>> IC logi i in a reversed D
>> marked in 3 lines ICE 2?26 maybe more numbers, ? maybe a 4
>> logo then 0 and more
>> XK4.. probably more numbers
>> probable pinning
>> p1 0.1uF to 0V
>> p2 to optocoupler
>> p3 over current sense
>> p4-p5 to Tx low side
>> p6 n/c
>> p7 supply <25V
>> p8 0V
>>
>
> SMPS controller ICs with the letters "ICE" as the first part of their
> type number are quite common. Such ICs are often coupled directly to a
> power FET switching element, but are just as commonly connected directly
> to a small SMPS Tx, particularly when it is a standby supply. I have
> always been amazed that these chips can stand the better part of 400
> volts across their internal FET, and that it can supply enough current
> to drive the Tx directly. I guess the thermal issues are dictated by how
> good the RDSon of the internal device is. The closer it is to zero ohms,
> the lower the dissipation, and some these days are pretty damn close to
> zero for all practical purposes.
>
> Arfa

Its the first time I've come across such a situation, still does not
look right. For something like a set-top box with no motors or laser and
a graphics processor that does not require a heatsink, I could see it
was possible




== 3 of 3 ==
Date: Mon, Jan 6 2014 12:49 am
From: N_Cook


On 05/01/2014 22:24, Arfa Daily wrote:
>
>
> "N_Cook" <diverse@tcp.co.uk> wrote in message
> news:la3dir$5hi$1@dont-email.me...
>> Burnt and burst SMPS supervisor on this otherwise no-name and little
>> chance Chinese thing. As laser and motor/s in the DVD deck and
>> heatsink bonded to a video chip a reasonable power draw.
>> But the SMPS IC , in a conventional 8 pin DIP package also contains
>> the Tx driver transistor. So air gap under the IC and reverse side of
>> pcb enlarged pad of pcb-copper as some sort of vain attempt at
>> heatsink. Thermal connection to this is via just pins 4 and 5 combined
>> in normal soldering , connected to the Tx. There is a hole through the
>> pcb as though for some sort of clip to go perhaps top and bottom of
>> the IC and bolted through to this under pad but no sign of anything
>> having been fitted there, no deformation of the tinning over the pad
>> around the hole. Turning over the unit and shaking over paper meant
>> the blasted away top part , mainly, of the IC emerged but no clip at all.
>> Is it possible to have combined supervisor and driver transistor in an
>> 8pin DIP package with no heatsink tab provision? or are there combined
>> SMPS TX with internal driver transistor buried in the base?
>> Also ps supply provision marked on pcb ac 85V - 250V
>> IC logi i in a reversed D
>> marked in 3 lines ICE 2?26 maybe more numbers, ? maybe a 4
>> logo then 0 and more
>> XK4.. probably more numbers
>> probable pinning
>> p1 0.1uF to 0V
>> p2 to optocoupler
>> p3 over current sense
>> p4-p5 to Tx low side
>> p6 n/c
>> p7 supply <25V
>> p8 0V
>>
>
> SMPS controller ICs with the letters "ICE" as the first part of their
> type number are quite common. Such ICs are often coupled directly to a
> power FET switching element, but are just as commonly connected directly
> to a small SMPS Tx, particularly when it is a standby supply. I have
> always been amazed that these chips can stand the better part of 400
> volts across their internal FET, and that it can supply enough current
> to drive the Tx directly. I guess the thermal issues are dictated by how
> good the RDSon of the internal device is. The closer it is to zero ohms,
> the lower the dissipation, and some these days are pretty damn close to
> zero for all practical purposes.
>
> Arfa

courtesy of alldatasheet with "start with" option
ICE2 starting it seems its like a
ICE2A265 with a different logo, same pinning on p4/5/6 at least
large datasheet , will have to read it when I get some time





==============================================================================
TOPIC: Are You Looking For Fridge Repair Service?
http://groups.google.com/group/sci.electronics.repair/t/67491ea6a7ce1fa6?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jan 5 2014 9:49 pm
From: Jade Birch


Ice cube fridge repair have been doing the business for many years. They provide low cost service and thus have reputation in the market with huge number of satisfied customers. If you want to more please visit http://icecubefridgerepair.com.au/




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