sci.electronics.repair - 25 new messages in 9 topics - digest

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

sci.electronics.repair@googlegroups.com

Today's topics:

==============================================================================
TOPIC: motherboard pwr_on pins resistance?
http://groups.google.com/group/sci.electronics.repair/t/65d60dc1b24d5107?hl=en
==============================================================================

== 1 of 2 ==
Date: Mon, Jan 31 2011 10:02 am
From: Adrian C

On 31/01/2011 17:42, mynick wrote:
> On Jan 31, 5:20 pm, Adrian C<em...@here.invalid> wrote:
>> On 31/01/2011 15:16, mynick wrote:
>>
>>> What you should get between those pins of a good PC mobo when you
>>> test with ohm-meter
>>
>> Normally, something other than a dead short.
>>
>> --
>> Adrian C
>
> are those directly connected to 'green and black wire' on atx power
> connector on motherboard

No, there normally is a transistor to switch that - and that is after a
circuit powered by the standby 5V supply (for a typical ATX rig) that's
involved in other power monitoring stuff. What you can measure as
resistance across the contacts could be anything, and not really conclusive.

What's the problem?

Maybe a read of the following may help

http://www.aitechsolutions.net/pchwtrblsht.html

--
Adrian C

== 2 of 2 ==
Date: Mon, Jan 31 2011 10:46 am
From: Paul

mynick wrote:
> On Jan 31, 5:20 pm, Adrian C <em...@here.invalid> wrote:
>> On 31/01/2011 15:16, mynick wrote:
>>
>>> What you should get between those pins of a good PC mobo when you
>>> test with ohm-meter
>> Normally, something other than a dead short.
>>
>> --
>> Adrian C
>
> are those directly connected to 'green and black wire' on atx power
> connector on motherboard

Not exactly.

First, look at the power on button on your PC.
It is a normally open, momentary contact switch.

When you push the button, it creates a pulse.
The logic input on the motherboard, has a pullup to +5VSB,
and when you push the button, the logic signal is shorted
to ground. A current of a milliamp or less may flow
through the switch. (So the front panel switch can be
a flimsy piece of crap, and still work. The front panel
switch doesn't need a multi-amp current rating or anything.)

The signal enters one of the motherboard ICs, and is
conditioned. It is eventually converted into an active low signal
called PS_ON#, driven by an open collector driver. The
motherboard IC means there is no direct path, from front
panel power on switch, to the PS_ON# signal. The motherboard
IC doing the conditioning, is running off +5VSB at the time
you push the button. If +5VSB is not available, then the
signal from the switch can't be conditioned, and can't be
acted upon.

(Note - in the following, I'm illustrating the principle
of cause and effect, not the timing. I didn't verify that
the timing looks exactly like this. But it gets the idea
across.)

PWR -----+ +------ Momentary pulse, active low
(Mobo | |
Header) +---+

PS_ON# -----+ OFF
(main |
20 pin) +---------- ON

The decoupling is more apparent, if you attempt to turn off
the PC, after the PC is booted. They have an option to check
a timer, which validates the state change on the PWR switch. You
have to press the front panel switch for at least 4 seconds,
to get the PC to power off. And the switch can be set in the BIOS,
to either do a controlled shutdown of the PC, or do a power off
instead. In the following diagram, I'm showing the "immediate"
power down option in action (it's how my PC is set up right now
in the BIOS). So after the four seconds is up, the power just
goes OFF, without warning the OS. This gives a "dirty" shutdown,
and potentially needs a CHKDSK later, to fix the file system.

PWR -----+ +------
(Mobo | |
Header) +---------------+

PS_ON# <- 4 sec -> |--------- OFF
(main |
20 pin) -----------------+ ON

For a sample motherboard schematic, you can take a look at
this old 440BX design.

http://www.intel.com/design/chipsets/designex/BXDPDG10.PDF

On page 32, B_SUSC drives pin 14 on the ATX power connector. That
is the green wire (PS_ON# signal) in the ATX standard. B_SUSC
stands for "buffered SUSC signal".

On page 18, you can see the creation of the B_SUSC (PS_ON#) signal.
A 74F07 open collector driver is used. That is a beefy OC driver,
with lots of current sink capability to ground. Modern PCs
are probably using something a bit weaker than that. To operate
PS_ON#, probably requires sinking a milliamp or two (I don't
know the exact figure right off hand). It shouldn't need a lot
of beef, but the beauty of the 74F07, is it is more likely to
survive all insults. Occasionally, on modern motherboards, the
equivalent to the 74F07 function, fails to sink properly to
ground (logic 0).

The SUSC# signal is coming from the Southbridge. So that is where the
"conditioned" control signal, comes out of the motherboard chipset in
this case.

Now, still on page 18, you can see in the Power Management section
of the Southbridge IC, they have a "PWRBT#" (Power Button) signal,
which is active low. That is the signal the Southbridge is going
to be looking for a pulse on. The power button circuit is back on page 32.

And on page 32, they kinda ruined my explanation. They chose to use
a momentary high pulse from the switch (switch pulls to 3VSB), plus
a CMOS Schmitt trigger/inverter to clean up the edge of the signal. The
74LVC14 turns that signal upside-down again, so as the PWRBT#
signal leaves page 32, it is an active low pulse. But as far as
I know, modern motherboards don't have that additional step.
The switch would be set up to pulse low, so the 74LVC14 would
not be present.

Using an ohmmeter, on the PWR/GND pair on the motherboard panel
header, should have little to do with the PS_ON# signal on the
main 20 or 24 pin cable, as they're separated by the logic in
at least one chip. In the Intel schematic, that was the Southbridge.
So ohming from PWR to PS_ON# wouldn't be telling you anything.

What you want to do, is check the voltage level on PS_ON# (green wire),
while you're fiddling with the front panel power button. If the
motherboard open collector driver, pulls the PS_ON# signal towards
ground (zero volts), then you should be seeing the power supply
fan come on and the main rails pop up.

On the input side, you'd monitor the voltage between PWR/GND
pair, when you push the front panel button. PWR should
drop to zero volts, for as long as the front power button
is pushed. Alternately, you can connect the front panel PWR
switch to your ohmmeter, and see if it reads zero ohms, when
the button is pushed. Sometimes, the flimsy button breaks,
and when you push the button, it no longer makes a proper
momentary contact.

HTH,
Paul

==============================================================================
TOPIC: Is it possible to repair a whole house surge suppressor?
http://groups.google.com/group/sci.electronics.repair/t/ce6c11f1c7a190bf?hl=en
==============================================================================

== 1 of 6 ==
Date: Mon, Jan 31 2011 10:08 am
From: Bob Villa

On Jan 30, 10:39 am, "Geoffrey S. Mendelson" <g...@mendelson.com>
wrote:
> mm wrote:
> > Is it possible to repair a whole house surge suppressor?
>
> > At 100 to 200 dollars, I don't want to keep buying new ones.
>
> Stop buying junk. MOV surge protectors are really worthless junk. Here in
> 230v land, when they go, they often do so with a bang and sometimes catch
> fire.
>
> Look at TransTector ones. They use silicon avalance diodes which when compared
> to MOVs are indestructable. They are more expensive but in the long run cheaper
> as they don't fail like MOV ones.
>
> You might also want to learn about how lightening works and how to avoid it.
>
> Contrary to what people believe (yes Franklin got it wrong) lightening flows
> from the GROUND UP. Once a path is opened from the ground, the polarity
> reverses and the usual flash you see flows downward.
>
> If you place grounded sharp pointed objects on top of buildings, you will
> CREATE lightening.
>
> If you place large "fuzzy" grounded objects on top of buildings, you will
> dissipate any charges that build up and reduce the chance of lightening
> strikes.
>
> I got rid of a lightening problem by placing a large 2m ham band (144mHz)
> antenna on my roof. It was a 12 foot beam with 10 vertical elements and
> 10 horizontal elements. At 144mHz it was an antenna, at DC (lightening)
> it was just a big blob of aluminum connected to ground. So as charges
> started to build up, they were dissipated.
>
> When I moved, I took down the antenna, I wonder what my neighbors thought
> when the lightening returned. :-(
>
> Geoff.
>
> --
> Geoffrey S. Mendelson N3OWJ/4X1GM
> Those who cannot remember the past are condemned to misquote it.

I think you mean lightning.

== 2 of 6 ==
Date: Mon, Jan 31 2011 10:13 am
From: "William Sommerwerck"

The "parallel" components (such as MOVs) in a surge suppressor will have
some effect on every other parallel line (lines connected to the same
phase). It doesn't matter whether any device is attached to the suppressor,
or is turned on.

== 3 of 6 ==
Date: Mon, Jan 31 2011 11:09 am
From: whit3rd

On Jan 31, 8:57 am, mm <NOPSAMmm2...@bigfoot.com> wrote:
> On Mon, 31 Jan 2011 22:16:51 +0900, "Michael Kennedy"
>
> <mikek...@crap.comcast.net> wrote:
>
> >>>"whit3rd" <whit...@gmail.com> wrote in message
> >>>news:844078cf-ed6d->>493b-a693-227b095fc__BEGIN_MASK_n#9g02mG7!__...__END_MASK_i?a63jfAD$z__@x17g2000yqa.googlegroups.com...
> >>>On Jan 30, 8:03 am, mm <NOPSAMmm2...@bigfoot.com> wrote:
> >>> Is it possible to repair a whole house surge suppressor?

> >>Ask your home insurance agent. It's unlikely that the
> >>prospect of homeowner repair of fire-safety items is
> >>going to be highly regarded.
>
> I didn't think of this until Michael posted but so what? Say I
> repaired it and say I didn't do a good job: My insurance doesn't
> require me to have a surge suprressor, so if I repair it and do a bad
> job, and it doesn't cause damage nor does it prevent damage the next
> time, they are no worse off than if I had never bought one. So they
> should still pay.

A whole-house suppressor is wired without any circuit breaker
protection, usually inside the circuit breaker box. Every item in
that box has a "UL" or other safety certification, and NONE are
intended for disassembly or repair. Your insurer may well claim
contributory negligence if the item has been modified or altered.
If something inside a 2 foot breaker box shoots 3 foot flames,
the house is at hazard.

Faulty fuses, breakers, or whole-house suppressors are intended
to remain safe (they're fail-safe devices); it's normal to replace
them when they fail.

== 4 of 6 ==
Date: Mon, Jan 31 2011 11:23 am
From: bud--

mm wrote:
> On Mon, 31 Jan 2011 08:37:32 -0800 (PST), GS <zekor@comcast.net>
> wrote:
>
>> On Jan 31, 9:45 am, GS <ze...@comcast.net> wrote:
>>> On Jan 30, 11:03 am, mm <NOPSAMmm2...@bigfoot.com> wrote:
>>>
>>>
>>>
>>>> Is it possible to repair a whole house surge suppressor?
>>>> At 100 to 200 dollars, I don't want to keep buying new ones.
>>>> I was going to install a whole house surge suppressor. When one of
>>>> them does its function, I think the MOV burns out, or some part does.
>>>> I haven't seen anything on the web about replacement modules for even
>>>> those units that might have them.
>>>> Will I be able to find, buy, and solder in replacement MOVs after the
>>>> first one burns out? (the green led goes out and the red led goes on)
>>>> I can't find any info about plug-in replacement parts, so if I can
>>>> repair any unit myself, I won't have to shop so thoroughly.
>>>> Items for sale, if interested:
>>>> I can install it myself. I'm considering, in ascending price order:http://www.amazon.com/Intermatic-IG1240RC3-Type-2-Protection-Device/d......
>>>> and less likely (plus two are required, one for each leg)http://www.amazon.com/Square-D-SDSA1175CP-ARRESTER-LIGHTNG/dp/B002GUZ1NI
>>> Its easy to find expensive ones. I guess if you can figure out how to
>>> take it apart
>>> you can fix it. I bought one a few months ago for $35. Here is anotherhttp://www.drillspot.com/products/122270/Square_D_SDSA1175_Surge_Arre...
>>> Drillspot sells Grainger stuff.
>
> Thanks. Now it's 56 dollars. I see that Amazon has this 36 also
> including shipping.
>>> greg
>> So I showed you the same model you showed first. But, you do NOT need
>> TWO.
>
> Oh, thank you. I got confused by the drawing, at
> http://surgelogic.com/wp-content/uploads/2010/08/SDSA1175_IB_8291-0014F.pdf
> which shows two for 3-phase (but only one for single-phase), and since
> it has only 3 wires, one to the neutral, but none to the ground like
> some others have.

It is intended for installation in a service panel. In the US, the
service panel (containing the service disconnect) has the neutral and
ground bonded together

In a subpanel (with separate neutral and ground bars) there would be
separate wires for the neutral and ground.

>
> Do you think I should to connect a surge suppressor to unused circuit
> breakers? Some instructions say to do that for increased sensitivity
> but others say nothing about it. Because the circuits I wanted to
> use are often off or almost totally off, just the baseline portable tv
> current or a cordless phone charger running.

It shouldn't matter.

(You are suppressing surges on the service busbars, not branch circuit.
Not obvious if you were saying something different.)

>
> It also says "Twist wires one half turn or more for
> every 12 in. (305 mm) of length." That means when all three wires are
> running together, right? In conduit or something? Once they
> separate, even if the wires are stranded, there's no point to twisting
> them, is there?

A surge is a very short-time event. Therefore it has relatively high
frequency components. The inductance of the wire is more important than
the resistance. Wire length is more important than it would seem. You
want a short connecting wires from the suppressor to the panel
connections. That is why the instructions say "keep the wire length as
short as possible. If the wires are in close proximity the wire
inductance is reduced. That is why the wires are slightly twisted.

>
>> There seems like a lot of confusion on protectors and the
>> manufacturers seem
>> to have various schemes going on. Some of the very small portable
>> devices by
>> Tripplite have ratings that indicate higher amps than the regular
>> whole house protectors. I installed the 'secondary" protector in my
>> breaker box

A useful rating for a MOV is its joule rating. UL does not have a
defined way of specifying joules. As a result some manufacturers are
using misleading or deceptive joule ratings on their products, which
puts honest manufacturers at a disadvantage. As a result, some
manufacturers no longer provide a joule rating. The amp rating is
equivalent, but defined. A high amp rating (like a high joule rating)
indicates a suppressor will have a long life. A plug-in suppressor with
high ratings could have an amp rating higher than a service panel
suppressor. (There is no possibility of a very high current on a branch
circuit; high current ratings just reflects a high joule rating.)

MOVs intrinsically try to limit the voltage across their terminals. In a
service panel the H-N voltages are limited (also H-H). That can result
in a high current to earth. Most of the energy in the incoming surge is
dumped to the earth. A small part of the energy is dissipated in the MOVs.

At a plug-in suppressor, the MOVs also limits the voltage H-G, N-G and
H-N. Because of the impedance of the ground wire, not much energy gets
dumped to the earth. But because of the impedance of the H and N, there
is similarly a very limited current that can flow. Energy dissipated in
the MOVs is surprisingly small (and there is another reason for this).
But the "ground potential" at the suppressor can be far different from
the service panel. All interconnected equipment needs to be connected to
the same suppressor and all external wires (power, phone, cable, ...)
need to go through the suppressor. The voltage on all wires is clamped
to the ground at the suppressor.

--
bud--

== 5 of 6 ==
Date: Mon, Jan 31 2011 11:31 am
From: GS

On Jan 31, 2:23 pm, bud-- <remove.budn...@isp.com> wrote:
> mm wrote:
> > On Mon, 31 Jan 2011 08:37:32 -0800 (PST), GS <ze...@comcast.net>
> > wrote:
>
> >> On Jan 31, 9:45 am, GS <ze...@comcast.net> wrote:
> >>> On Jan 30, 11:03 am, mm <NOPSAMmm2...@bigfoot.com> wrote:
>
> >>>> Is it possible to repair a whole house surge suppressor?
> >>>> At 100 to 200 dollars, I don't want to keep buying new ones.
> >>>> I was going to install a whole house surge suppressor. When one of
> >>>> them does its function, I think the MOV burns out, or some part does.
> >>>> I haven't seen anything on the web about replacement modules for even
> >>>> those units that might have them.
> >>>> Will I be able to find, buy, and solder in replacement MOVs after the
> >>>> first one burns out? (the green led goes out and the red led goes on)
> >>>> I can't find any info about plug-in replacement parts, so if I can
> >>>> repair any unit myself, I won't have to shop so thoroughly.
> >>>> Items for sale, if interested:
> >>>> I can install it myself. I'm considering, in ascending price order:http://www.amazon.com/Intermatic-IG1240RC3-Type-2-Protection-Device/d......
> >>>> and less likely (plus two are required, one for each leg)http://www.amazon.com/Square-D-SDSA1175CP-ARRESTER-LIGHTNG/dp/B002GUZ1NI
> >>> Its easy to find expensive ones. I guess if you can figure out how to
> >>> take it apart
> >>> you can fix it. I bought one a few months ago for $35. Here is anotherhttp://www.drillspot.com/products/122270/Square_D_SDSA1175_Surge_Arre...
> >>> Drillspot sells Grainger stuff.
>
> > Thanks. Now it's 56 dollars. I see that Amazon has this 36 also
> > including shipping.
> >>> greg
> >> So I showed you the same model you showed first. But, you do NOT need
> >> TWO.
>
> > Oh, thank you. I got confused by the drawing, at
> >http://surgelogic.com/wp-content/uploads/2010/08/SDSA1175_IB_8291-001...
> > which shows two for 3-phase (but only one for single-phase), and since
> > it has only 3 wires, one to the neutral, but none to the ground like
> > some others have.
>
> It is intended for installation in a service panel. In the US, the
> service panel (containing the service disconnect) has the neutral and
> ground bonded together

I have yet to see suppressor not intended to be connected to breakers
in a service
panel.

I also don't like to call these surge, but SPIKE yes.
Surges to me a re very slow increases in voltage over the
safe limit.

You can usually make local neutrals by connecting ground
to a neutral, or make it using an isolation transformer, which
makes ground to neutral noise non existent at that point.

greg

> In a subpanel (with separate neutral and ground bars) there would be
> separate wires for the neutral and ground.
>
>
>
> > Do you think I should to connect a surge suppressor to unused circuit
> > breakers? Some instructions say to do that for increased sensitivity
> > but others say nothing about it. Because the circuits I wanted to
> > use are often off or almost totally off, just the baseline portable tv
> > current or a cordless phone charger running.
>
> It shouldn't matter.
>
> (You are suppressing surges on the service busbars, not branch circuit.
> Not obvious if you were saying something different.)
>
>
>
> > It also says "Twist wires one half turn or more for
> > every 12 in. (305 mm) of length." That means when all three wires are
> > running together, right? In conduit or something? Once they
> > separate, even if the wires are stranded, there's no point to twisting
> > them, is there?
>
> A surge is a very short-time event. Therefore it has relatively high
> frequency components. The inductance of the wire is more important than
> the resistance. Wire length is more important than it would seem. You
> want a short connecting wires from the suppressor to the panel
> connections. That is why the instructions say "keep the wire length as
> short as possible. If the wires are in close proximity the wire
> inductance is reduced. That is why the wires are slightly twisted.
>
>
>
> >> There seems like a lot of confusion on protectors and the
> >> manufacturers seem
> >> to have various schemes going on. Some of the very small portable
> >> devices by
> >> Tripplite have ratings that indicate higher amps than the regular
> >> whole house protectors. I installed the 'secondary" protector in my
> >> breaker box
>
> A useful rating for a MOV is its joule rating. UL does not have a
> defined way of specifying joules. As a result some manufacturers are
> using misleading or deceptive joule ratings on their products, which
> puts honest manufacturers at a disadvantage. As a result, some
> manufacturers no longer provide a joule rating. The amp rating is
> equivalent, but defined. A high amp rating (like a high joule rating)
> indicates a suppressor will have a long life. A plug-in suppressor with
> high ratings could have an amp rating higher than a service panel
> suppressor. (There is no possibility of a very high current on a branch
> circuit; high current ratings just reflects a high joule rating.)
>
> MOVs intrinsically try to limit the voltage across their terminals. In a
> service panel the H-N voltages are limited (also H-H). That can result
> in a high current to earth. Most of the energy in the incoming surge is
> dumped to the earth. A small part of the energy is dissipated in the MOVs.
>
> At a plug-in suppressor, the MOVs also limits the voltage H-G, N-G and
> H-N. Because of the impedance of the ground wire, not much energy gets
> dumped to the earth. But because of the impedance of the H and N, there
> is similarly a very limited current that can flow. Energy dissipated in
> the MOVs is surprisingly small (and there is another reason for this).
> But the "ground potential" at the suppressor can be far different from
> the service panel. All interconnected equipment needs to be connected to
> the same suppressor and all external wires (power, phone, cable, ...)
> need to go through the suppressor. The voltage on all wires is clamped
> to the ground at the suppressor.
>
> --
> bud--

== 6 of 6 ==
Date: Mon, Jan 31 2011 12:25 pm
From: Fred

mm <NOPSAMmm2005@bigfoot.com> wrote in
news:162bk6l0qi1ch7st69ish5urh344qpkacb@4ax.com:

> Is it possible to repair a whole house surge suppressor?
>
> At 100 to 200 dollars, I don't want to keep buying new ones.
>

Totally unnecessary. Call your power company about every other year and
file a report that your lights are blinking when the wind blows. They'll
send out a service truck to investigate with a guy we don't pay anywhere
near enough to risk his life working around the 23KV primary on the pole.
Ask him to check your house's connections at the pole for tightness,
paying special attention to the NEUTRAL connections, which are the ONLY
way your 120VAC can surge up to 240VAC if neutral comes loose and there's
a big load on the OTHER phase from the one your computer is on. While
he's there, ask him to inspect the grounding on your meter base and
verify its lightning gap hasn't been damaged by any hits. It's inside
the meter base and he's the only one with a replacement seal to install.

Please consider offering these great lineman a refreshing beverage to say
thank you for the free service they provide you. I usually show up with
a cold Coke for each of them as they are nesting the bucket and stowing
their HV gloves. I'm more of a shock to them than anything the
generators can produce....(c;] If it's quitting time when they finish, I
move from Coke to a quality beer as they've had a hard shift in the hot
sun. Guess who's power gets restored FIRST after the next storm!....(c;]

If your house if FIRMLY attached to the pole transformer, "surges" are
virtually impossible UNLESS you get hit by lightning. NO surge
protector, no matter how expensive, says anything about LIGHTNING
PROTECTOR, ever. That would be a lie. The 23KV primary phase of
America's 3 phase Tesla multiphase AC power system is quite stable. The
natural magnetic hysteresis of the 60 hz core in your distribution
transformer prevents any pulses from being sent to your house until the
lightning protector in its primary fuse holder explodes in defeat.

"Surge Protector" is a great sales gimmick. If you want to save your
computer, buy it a nice UPS to protect it from LOSING power, especially
during disk write operations where you can lose EVERYTHING on that drive.

If you're intent on spending money, please consider replacing your
breaker panel breakers on all electrical outlets and appliances with GFI
breakers, making it much less possible to kill a child sticking a metal
object into America's absurdly designed bladed receptacles designed in
1900. The only way to get shocked after their installation is to get
right across the powerline from hot to neutral, which rarely happens to
kill anyone. I support GFI installation 100%!

==============================================================================
TOPIC: Broken CFL
http://groups.google.com/group/sci.electronics.repair/t/75850803cb529797?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Jan 31 2011 10:12 am
From: Sjouke Burry

bz wrote:
> Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote in
> news:4d45ff79$0$8916$703f8584@textnews.kpn.nl:
>
>> bz wrote:
>> cut
>>> A few drops spilled in the corner of the room where you work will
>>> evaporate slowly and be accumulated in your system, causing mercury
>>> poisoning.
>>>
>>> Removal of ALL spilled mercury is NECESSARY and requires careful clean
>>> up because it likes to break up into extremely small droplets and they
>>> can splash long distances.
>> Hm... According to your theory I should have been dead
>> already 5 times over.
>> I have to disappoint you, still alive(67) and going strong.
>
> Depends on the ventilation in the area where you work and the amount of
> time you spend there.
>
> Also, you are unlikely to die of chronic mercury poisoning.
>
> Do you have any of these symptoms?
>
> http://www.mercurypoisoned.com/symptoms.html
>
>
No :)

==============================================================================
TOPIC: possible problem with Sony flat-face WEGA
http://groups.google.com/group/sci.electronics.repair/t/8fc4ce0a3ea9ba13?hl=en
==============================================================================

== 1 of 4 ==
Date: Mon, Jan 31 2011 10:27 am
From: Chuck

On Sun, 30 Jan 2011 07:21:36 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

>I'm posting this to see if anyone /knows/ the answer, or has a reasonable
>suspicion. I do not want to initiate an interminable chain of speculation.
>
>I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service
>manual. The set has gotten heavy use over the past decade; I often leave it
>on when I go to bed. It wasn't cheap, and I'd like to get at least another
>five years out of it. For a non-HD CRT set, it has an excellent picture,
>especially with RGB signals from a DVD player.
>
>When the set's turned on, the HV is apparently shut off, so that the CRT
>heater has time to come to full temperature, to avoid stripping the cathode.
>(This is speculation.) Though sound comes on almost immediately, it takes
>about 10 seconds for the raster to appear.
>
>Recently I've noticed "something new". For about two seconds after the
>raster comes on, the black level is too light. You can see the image
>"darkening" as the black level drops to its "correct" point. This occurs
>only when the set is "cold"; cycling the power doesn't cause this.
>
>I'm hoping someone will say "I've seen this. It's the ___________."
>Troubleshooting this set won't be easy (if only because it's close to the
>wall on a near-immovable stand). I don't want to tear into it until I'm
>reasonably certain I can fix it on the first try.
>
>Thanks in advance.

William, the condition is usually caused by the crt cathode emission
becoming weaker. When the picture no longer comes on, adjusting the
screen control higher will allow the set to work for a few months to a
year more. Chuck

== 2 of 4 ==
Date: Mon, Jan 31 2011 11:41 am
From: "William Sommerwerck"

> The condition is usually caused by the CRT's cathode
> emission becoming weaker. When the picture no longer
> comes on, adjusting the screen control higher will allow
> the set to work for a few months to a year more.

I kinda expected that. If you're correct, it looks like I won't get my
money's worth out of the set.

I wonder if anyone still makes CRT heater boosters. <grin> Remember those?

== 3 of 4 ==
Date: Mon, Jan 31 2011 12:53 pm
From: "Michael A. Terrell"

William Sommerwerck wrote:
>
> > The condition is usually caused by the CRT's cathode
> > emission becoming weaker. When the picture no longer
> > comes on, adjusting the screen control higher will allow
> > the set to work for a few months to a year more.
>
> I kinda expected that. If you're correct, it looks like I won't get my
> money's worth out of the set.
>
> I wonder if anyone still makes CRT heater boosters. <grin> Remember those?

If they use DC on the fliament check for a bad electrolyytic in it's
power supply. I used to add a filamnet transformer to series string TV
sets with a dropping diode to power an 84 volt string of filaments.
They barely lasted a year from new, without the modification.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 4 of 4 ==
Date: Mon, Jan 31 2011 2:15 pm
From: "William Sommerwerck"

> If they use DC on the filament, check for a bad electrolyytic
> in its power supply. I used to add a filament transformer to
> series string TV sets with a dropping diode to power an 84
> volt string of filaments. They barely lasted a year from new,
> without the modification.

Well, this set's over 10 years old. I'll pull out the service manual and
give it a look.

==============================================================================
TOPIC: Pet hates ?
http://groups.google.com/group/sci.electronics.repair/t/e7925b5c2233e9ec?hl=en
==============================================================================

== 1 of 2 ==
Date: Mon, Jan 31 2011 10:49 am
From: "Michael A. Terrell"

N_Cook wrote:
>
> Ron D. <ron.dozier@gmail.com> wrote in message
> news:3704567b-3469-47f5-af0f-4251da36f1d8@17g2000prf.googlegroups.com...
> > heat sink goop
> >
> > cars with both metric and english fasteners
> >
> > bristol spline srews
>
> Could you describe a "bristol spline screw" Google-images no help other than
> they are used on 30KV rated relays

Bristol was used in electronic equipment build by the US during
W.W.-II.

http://en.wikipedia.org/wiki/Wrench, almost half way down the page.

http://www.bristolwrench.com/ still makes them.

http://www.bristolwrench.com/spline.pdf

They are availible from a lot of industrial tool dealers.

A lot of people called them 'Spline Wrenches' instead of Bristol
Wrenches.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 2 of 2 ==
Date: Mon, Jan 31 2011 11:50 am
From: Chuck

On Fri, 28 Jan 2011 15:58:53 -0000, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

>
>
>"Geoffrey S. Mendelson" <gsm@mendelson.com> wrote in message
>news:slrnik1vml.5bn.gsm@cable.mendelson.com...
>>
>>
>> I wrote:
>>>> Instead of the doomed
>>>> national health plan they use in the UK,
>>
>> Arfa Daily wrote:
>>
>>> Meaning what, exactly ... ?
>>
>> Until the UK figures out a way to separate the National Health from the
>> general
>> budget, it's going to be "asuterity"'ed into nothingness.
>>
>> Since it is funded from the same fund as everything else, and has no
>> competition, it just spends and spends and provides less services as money
>> dries up.
>>
>> For example, according to a large cancer support organization around 90%
>> of
>> all cancer patients EVER see an oncologist (cancer specialist). This is up
>> from less than 80 10 years ago.
>>
>> I'll give you an example I read in Reader's Digest. Currently when a tube
>> gets partially used it is impossible to squeeze the medicine out. Someone
>> in the UK invented a new tube with a knob on the bottom, costing about 1.5
>> UKP
>> each. This was going to save the national health millions.
>>
>> My wife goes to the "dollar store" and buys a set of plastic clamps which
>> do the same thing. We use them for toothpaste, but you could use them
>> for anything in a tube. If you had them made to order and shipped in bulk,
>> they would cost a few pence.
>>
>> Geoff.
>>
>> --
>
>
>Considering that you neither reside in the UK, nor have cause to make use of
>the facilities of our health service, I find it a little presumptuous of
>you to feel that you are qualified to pass comment on its continuing
>viability, or otherwise. One thing that you need to understand, is that
>NHS-bashing is a national sport here, and articles such as that which you
>are quoting as being read by your wife, appear every week in the daily and
>Sunday press. The Readers' Digest is no more separated from this practice
>than any other press offerings, despite the way it tries to present itself.
>
>As far as the content of the story goes, with the ongoing restructuring of
>the health service, I very much doubt that medicines are being wasted in the
>way described, as an 'across the board' event. For sure, somebody has
>probably seen this being done in some health establishment somewhere, and
>extrapolated this into common practice. The truth is probably much removed
>from that. The people 'on the ground' in the health service are ordinary
>folk like you and I, and I don't suppose they like to see waste in their
>working lives, any more than they do in their personal ones. I'm sure that
>if there is a way to get the remaining medicine out of the tube, the vast
>majority of employees are doing so. Apart from that, we don't actually know
>that there are not valid operational reasons why sometimes, medicines left
>in containers may be thrown away. There could be contamination issues, or
>maybe the medicine starts to deteriorate as soon as it is opened, and then
>has a very short ongoing shelf life. Whilst there may be some truth in this
>story, I think it needs to be considered with a degree of scepticism. These
>stories are told in a way as to be deliberately provocative and to cause
>outrage at supposed 'waste in the NHS'.
>
>For the most part, the NHS delivers a first class service to patients and,
>whilst there are errors made - and you will always be able to find someone
>that has got some outrageous claim about how they or their uncle Willy or
>their friend down the street was badly treated - the vast majority of people
>are perfectly satisfied with the treatment and service that they receive,
>and are glad that it is there for them 24 / 7 / 365, without having to worry
>about who's going to pay. You must also remember that it is a huge
>employer - I think I recently read somewhere that it is the largest employer
>in the whole of Europe - and for that reason, if no other, there is going to
>be issues with overstaffing and waste from time to time. This is true of any
>large organisation, so is sure to be of a mega one like the NHS.
>
>As to your comments about percentages of cancer patients being seen by an
>oncologist, I'm not sure that I follow exactly what you were trying to say
>there. With UK NHS patients, 100% of people will be referred to an
>appropriate consultant (highest level of hospital-based specialist doctor /
>surgeon in any particular field) if their general practitioner deems it
>necessary. Patients suspected of having cancer are referred immediately, and
>often seen within a few days. It is not unusual for treatment - either
>medical, nuclear, surgical or all three, to be started within a week of
>confirmed diagnosis.
>
>So no. I think, as a resident of the UK, and a user of the NHS for the whole
>of my life, you are quite wrong, and the health service is no more 'doomed'
>than it has been at any time in its now quite lengthy existence. The current
>round of financial austerity measures that have had to be implemented by
>this incoming government to try to clear up the mess we are in, are sure to
>have some impact on a very heavy tax-spender such as the NHS, but it will
>certainly not be "austerity'd into nothing" as you so quaintly put it. The
>hospital managers will have to learn better control of their finances, as
>they have had to in the past. The only reason that they have forgotten how
>to do this now, is that the previous government was of a socialist flavour,
>and they thought that the way to improve everything, including the NHS, was
>to throw money at it. This has resulted in a top-heavy management structure,
>and a lot of internal waste. Once this has been addressed, the NHS will
>again be able to deliver cost-effective high quality care, as it has in the
>past.
>
>Arfa

In the United States, the health insurers and their media shills
concoct horror stories about the various European goverment managed
health care systems. The average American, most of which who haven't
lived in other countries, believe the lies. Chuck

==============================================================================
TOPIC: CRT Monitor Philips black screen when cold
http://groups.google.com/group/sci.electronics.repair/t/5e3cab73ac7d259c?hl=en
==============================================================================

== 1 of 2 ==
Date: Mon, Jan 31 2011 11:43 am
From: Fred

Sylvia Else <sylvia@not.here.invalid> wrote in news:8qkkteFd62U1
@mid.individual.net:

> Depends how much it costs to fix the CRT. If it's a bad cap, it might be
> obvious which one just by looking at it (bulging top and/or leaking),
> and the fix, excluding the OP's time, may cost a few dollars.
>
> The OP should of course make sure he's aware of the hazards associated
> with CRTs even when there's no power applied.
>
> Sylvia.
>
>

OP's savings in electric bill ALONE justifies buying the new LCD, even if
he can fix it for free.

== 2 of 2 ==
Date: Mon, Jan 31 2011 12:53 pm
From: "Michael A. Terrell"

Fred wrote:
>
> Sylvia Else <sylvia@not.here.invalid> wrote in news:8qkkteFd62U1
> @mid.individual.net:
>
> > Depends how much it costs to fix the CRT. If it's a bad cap, it might be
> > obvious which one just by looking at it (bulging top and/or leaking),
> > and the fix, excluding the OP's time, may cost a few dollars.
> >
> > The OP should of course make sure he's aware of the hazards associated
> > with CRTs even when there's no power applied.
> >
> > Sylvia.
> >
> >
>
> OP's savings in electric bill ALONE justifies buying the new LCD, even if
> he can fix it for free.

That depends on how much use it gets.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

==============================================================================
TOPIC: Need models to buy, and to avoid for laptop computer
http://groups.google.com/group/sci.electronics.repair/t/db8856ed635bbd2f?hl=en
==============================================================================

== 1 of 2 ==
Date: Mon, Jan 31 2011 11:45 am
From: Jeff Liebermann

On Sun, 30 Jan 2011 23:45:27 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:
(blah...blah...blah)

...and just when you thought it was safe to buy a new laptop:
"Intel hit with chipset design flaw in Sandy Bridge rollout"
<http://www.zdnet.com/blog/btl/intel-hit-with-chipset-design-flaw-in-sandy-bridge-rollout/44257?tag=nl.e539>

"The faulty support chip has only been shipping since Jan. 9.
Customers impacted will be those that bought second-generation
Core i5 and Core i7 systems."

Swell.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 2 of 2 ==
Date: Mon, Jan 31 2011 11:58 am
From: JeffM

hrhofmann@ att.net wrote:
>My wife's Dell computer has died
>
Several of us are assuming you keep a boot-to-a-desktop
Linux CD on hand for first-eschelon tests of hardware vs OS.
This one works on just about anything.
http://google.com/search?q=MEPIS+antiX+64MB+128MB
Some folks pronounce antiX as "antiques".

>I am looking for suggestions on brands to buy and to avoid
>
A company I avoid in all matters is Sony.
http://google.com/search?q=cache:NFEfVX2OV6oJ:boingboing.net/2006/10/24/sony-assassinates-am.html+does.not.conform+selling-*-PSP-consoles-from-Asia+carry-CE-*-*-*-marks+rootkits+*-lock-out-homebrew-software+*-*-crippling-*-PSP+*-*-teaching-*-dances-to-*-Aibos+war-against-its-*-customers+*-European-customers+compromised.*.computer.networks&strip=1
http://tinyurl.com/Sony-s-War-On-Its-Customers
http://boingboing.net/2006/10/24/sony-assassinates-am.html

They've screwed up way too many times for me to trust them.
http://google.com/search?q=Sony+laptop-batteries+fires
http://google.com/search?q=Sony+rootkit
http://google.com/search?q=Sony+OtherOS+%2BOtherOS
http://google.com/search?q=Sony+George-Hotz

As the other Jeff has said,
most of the stuff comes from just a few factories these days;
what matters most is how you are treated AFTER the sale.
Sony FAILS.

==============================================================================
TOPIC: surges slowly destroying
http://groups.google.com/group/sci.electronics.repair/t/97cd7b53147e2809?hl=en
==============================================================================

== 1 of 3 ==
Date: Mon, Jan 31 2011 11:50 am
From: Fred

mm <NOPSAMmm2005@bigfoot.com> wrote in
news:7a1bk6to1c0a86i8e21ut7o4ldhpe09n43@4ax.com:

> Question at ====> line:
>
> http://www.squidoo.com/small-led-light-surge-protector
>
> Small LED Light As Indicator In A Surge Protector
> However, the most beneficial advancement of late is that small LED
> bulbs are now utilized as indicator lights in the device that protects
> equipment from power surges, the surge protector. Surges, otherwise
> called voltage spikes or transient surges, are abrupt increases in
> household voltage what happen when high-energy appliances or computers
> are powered on. Such surges can take place in excess of 2,000 times
> per year in homes, slowly destroying the components of a home
>
> =====> Is this sentence true. Many times a year? And more
> importantly, *slowly* destroying. Not ruined or "no damage"?
>
> computer, a cell phone, and other fragile electronic equipment. Other
> home appliances, furnaces, air conditioners, washers, dryers, and the
> like, are also know to create surges which travel back through the
> main breaker panel and out again through the home wiring.
>

Anything with a modern switching power supply is immune from anything the
power company "surges", usually caused by loose neutral connections
causing an unbalanced phase voltage, can cause. Switchers are rated from
around 80VAC to 270VAC (not cast in stone) and will simply absorb any
voltage changes as the input of these supplies is just a big rectifier
with big storage capacitors to feed DC to the switching regulators.
Surges are turned into output power, nicely leveled by the fast
switcher's reaction time. Your computer power supply is one of them.

What's FAR more important than a "surge protector" it doesn't need is a
UPS to hold up the AC line voltage on brownouts and interruptions that
just love to occur during those all-important disk write
operations....leaving the disk trashed with half a FAT updated and half a
FAT not. That's better than a good hacker can ever achieve trying to
trash a system!

== 2 of 3 ==
Date: Mon, Jan 31 2011 11:53 am
From: Fred

"Phil Allison" <phil_a@tpg.com.au> wrote in
news:8qmb5aFui2U1@mid.individual.net:

>
> "bud--"
>>
>> Surges damage cell phones? I would ignore anything this source says.
>
> ** Nor would I.
>
> Just a few days ago I took the opportunity to break open a Nokia cell
> phone charger - the only thing that MIGHT be damaged by voltage spikes
> on the AC supply.
>
> The incoming AC connects first to a 10 ohm fusible resistor, then a 4
> x 1N4007 diode bridge then a 4.7uf 400V filter electro. Very simple
> and very robust.
>
> Any surge on the AC that killed the Nokia would take out all the CFLs
> and many other things too.
>
>
>
> .... Phil
>
>
>
>
>
>
>
>
>
>

Yep, that supply will eat any surges caused by loose line connections,
switching motors on and off, etc......for lunch, convert it to a
regulated DC output and feed it to the phone as if nothing happened.

I don't buy any wall warts that aren't switchers any more.....even to
charge the wine cork puller.

== 3 of 3 ==
Date: Mon, Jan 31 2011 12:06 pm
From: Fred

Jeff Liebermann <jeffl@cruzio.com> wrote in
news:ra6ck65t4chmj5mtqonopf8t7vj2msbrhd@4ax.com:

> A good MOV protector will absorb about 1000 Joules. An
> LED can hardly absorb perhaps 1 Joule. If you decode the muddled
> intent of the article, the LED light probably just lights when there
> has been a surge.
>

LED is a surge INDICATOR. If there is a hole where the LED used to
protrude through the case with small radiating black carbon trails, it
INDICATES a surge has taken place!

Obviously, only BLUE LEDs contain any kind of magic, because all the most
expensive computers all have BLUE leds lighting up everything! Recently,
blue LEDs have been found to increase the acceleration and top end speed
of production motorcycles by at least 12%! Having blue leds lighted near
a 1935-designed Harley-Davidson engine V-twin is MOST effective.....

==========================================================

When I was a smartassed young sailor aboard USS Everglades (AD-24), we
got a fresh new Ensign, straight out of some EE mill put in charge of the
electronics gang. After some really stupid pronouncements, it was
decided to build our new Ensign a "Fuse Tester" and present it to him at
Quarters. He was most impressed. There were 16 different fuse holders
with a big neon indicator light that stayed lit while it was plugged in.

The fuses were in series with a big pushbutton switch marked "TEST" you
pressed while watching the big neon indicator. Pressing the TEST button
put the fuses right across the power line, causing the fuse to blow, of
course, and the indicator to blink off until the fuse blew which told you
the fuse you tested WAS good, before you blew it in the tester, of
course.

Our Ensign must have blown a hundred fuses of different size and amps. I
don't think he ever actually "got" the joke. He was that dumb.

Of course, Navy promoted him to LTJG and transferred him to a more
important post after a short cruise to a more suitable position for a
young, aspiring engineer who couldn't figure out which end of the
resistors was positive (obviously, the end with the bands).

Luckily, our captain kept him out of our hair and away from any vital
equipment that might put lives in jeopardy....standing watches and
looking important.

==============================================================================
TOPIC: Laptop not charging.
http://groups.google.com/group/sci.electronics.repair/t/3f52116e8141f1a4?hl=en
==============================================================================

== 1 of 3 ==
Date: Mon, Jan 31 2011 12:50 pm
From: Baron

T i m Inscribed thus:

> On Sun, 30 Jan 2011 19:30:28 +0000, Baron
> <baron.nospam@linuxmaniac.nospam.net> wrote:
>
>>T i m Inscribed thus:
>>
>>> Yesterday, thinking it /could/ be a socket and where the tiny inner
>>> / 3rd pin connects (thinking it might be a 'sense' wire and a socket
>>> was cheap etc) I changed it for him but again, no improvement.
>>
>>That third wire the centre pin, is a one wire data interface !
>
> Ah.
>
>> The idea
>>is to prevent you from using a charger that is/was not supplied by the
>>manufacturer.
>
> So this is how it 'knows' it's a 65W or 90W charger and that a genuine
> one is present etc?

Yep !
Also notice that most, if not all, manufacturers are moving in that
direction. I'm surprised that it hasn't happened that way on desktop
machines.

>> Its quite possible that since the laptop works happily
>>from the charger, that the communications inside the laptop charging
>>circuits has been damaged.
>
> I guess anything is possible with that level of 'intelligence. ;-(
>> The charger board and the mainboard come as a pair. A salvaged
>> charger board will not work with a different mainboard.
>
> Great (not). ;-(

I agree its not nice.

>>HTH
>
> It has (thanks), in so far as we needn't waste any money on just a
> charger board.
>
> So, unless we can pick up a working system / charger board pair we
> have a mains only laptop. ;-(
>
> Cheers, T i m

Its a very crafty way of preventing non-authorised repair agents from
fixing kit on the cheap.

--
Best Regards:

Baron.

== 2 of 3 ==
Date: Mon, Jan 31 2011 1:09 pm
From: Baron

bz Inscribed thus:

> I have fixed many 'bad' supplies by cutting the 'broken' spot out of
> the cord. It is usually where the cord gets the most flexing.
>
> finding it, cutting and splicing the cord to fix it can be
> challenging.
>
> I usually cut a few inches from the power plug and check with an ohm
> meter. If I was lucky, that is the end and some work with a razor
> knife, soldering iron and hot glue and you are back working.
> If it is at the power brick end, you will probably have to crack the
> brick open with a screwdriver and solder the cord into the brick.
>
> Sometimes, I end up with repairs at both ends and a cord that is much
> shorter, in between.

Just a note: In the UK its not allowed/legal to do a repair where the
integrity of the repaired item, in this case, the PSU is compromised
such that it could be a hazard to health.

The PSU/brick case is welded together in order to prevent any attempt to
repair it. Making a joint in the cable feeding the appliance is not
considered safe.

Replacing the power connector on the end of the cable, if you can get
one, would be allowed. Unfortunately the manufactures have gone to
great lengths to prevent these from being available from any source.

> Hint for all laptop supply users:
> NEVER NEVER NEVER wrap the cord tightly around the supply, bending it
> sharply near where it exits the supply.
> Coil it loosely and let it look messy.
>
> NEVER NEVE NEVER put a aharp bend in the cord near the plug nor near
> the brick.

I second these last comments !

--
Best Regards:
Baron.

== 3 of 3 ==
Date: Mon, Jan 31 2011 1:11 pm
From: Meat Plow

On Mon, 31 Jan 2011 20:50:11 +0000, Baron wrote:

> T i m Inscribed thus:
>
>> On Sun, 30 Jan 2011 19:30:28 +0000, Baron
>> <baron.nospam@linuxmaniac.nospam.net> wrote:
>>
>>>T i m Inscribed thus:
>>>
>>>> Yesterday, thinking it /could/ be a socket and where the tiny inner /
>>>> 3rd pin connects (thinking it might be a 'sense' wire and a socket
>>>> was cheap etc) I changed it for him but again, no improvement.
>>>
>>>That third wire the centre pin, is a one wire data interface !
>>
>> Ah.
>>
>>> The idea
>>>is to prevent you from using a charger that is/was not supplied by the
>>>manufacturer.
>>
>> So this is how it 'knows' it's a 65W or 90W charger and that a genuine
>> one is present etc?
>
> Yep !
> Also notice that most, if not all, manufacturers are moving in that
> direction. I'm surprised that it hasn't happened that way on desktop
> machines.

The 3rd pin on a traditional Dell 19vdc 4500mah is a dummy. I'm using one
on an Asus laptop that had the same requirements. Only thing you need to
watch is using an underrated PSU as you probably will overtax it. Having
more power capacity isn't an issue for obvious reasons. I'm also using an
HP 19vdc supply on a Toshiby. All these have similar CPU configurations
and requirements within +- 10%.

--
Live Fast, Die Young and Leave a Pretty Corpse

==============================================================================

You received this message because you are subscribed to the Google Groups "sci.electronics.repair"
group.

To post to this group, visit http://groups.google.com/group/sci.electronics.repair?hl=en

To unsubscribe from this group, send email to sci.electronics.repair+unsubscribe@googlegroups.com

To change the way you get mail from this group, visit:
http://groups.google.com/group/sci.electronics.repair/subscribe?hl=en

To report abuse, send email explaining the problem to abuse@googlegroups.com

==============================================================================
Google Groups: http://groups.google.com/?hl=en

Electronics

sci.electronics.repair - 25 new messages in 9 topics - digest

No Response to "sci.electronics.repair - 25 new messages in 9 topics - digest"

Post a Comment

Blog Roll

Blog Archive