sci.electronics.repair@googlegroups.com

Today's topics:

* White LED spectrum? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/7b379dacdacd2dfe?hl=en
* SMPS design ... - 4 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/fafbacc4bb94c7c0?hl=en
* computer problems - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/d5b26a3411c63324?hl=en
* Wanted CCFL tube for 22 inch widescreen LCD - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/ee497293d388f924?hl=en
* A cordless phone question - 4 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/dbf17b88cb06d8a8?hl=en
* O2 Joggler power supply voltage and wattage ? - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/46d63938d1736d01?hl=en
* Emerson Clock Radio Model CK5235 - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/78605b0d7e63fa5c?hl=en
* Re-winding solenoids. - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/fd7d7813745e3da8?hl=en

==============================================================================
TOPIC: White LED spectrum?
http://groups.google.com/group/sci.electronics.repair/t/7b379dacdacd2dfe?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, Oct 22 2011 12:17 am
From: DaveC

> I really have no help for the question asked, but I think people
> interested in the subject may have an answer to one of my questions.

And I have one word for you: HIJACK.

If you don't have an answer to the OP's question, fine. If you have a
question, START YOUR OWN THREAD.

==============================================================================
TOPIC: SMPS design ...
http://groups.google.com/group/sci.electronics.repair/t/fafbacc4bb94c7c0?hl=en
==============================================================================

== 1 of 4 ==
Date: Sat, Oct 22 2011 5:25 am
From: "Ian Field"

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:9geii5F9l4U1@mid.individual.net...
>
> "Arfa Daily"
>
>
> ** Get utterly fucked
>
> - you stupid, bullshitting, pommy TROLL

Missing your dingo mommy & daddy?

== 2 of 4 ==
Date: Sat, Oct 22 2011 5:29 am
From: "Ian Field"

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:Uuooq.6890$UN2.5702@newsfe04.ams2...
>
>
> "Ian Field" <gangprobing.alien@ntlworld.com> wrote in message
> news:sqdoq.860$gS1.157@newsfe17.ams2...
>>
>> "Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
>> news:MB3oq.5714$_p4.409@newsfe19.ams2...
>>> <snip>
>>>>
>>>>
>>>> Are the 330pF multilayer ceramic that could have metalisation creep /
>>>> cracks/ unreliable /leaky from humidity. I would replace them with a
>>>> different brand/construction
>>>>
>>>>
>>>
>>> It would probably be worth doing some further checks on those caps to
>>> make sure that they are not any part of the problem
>>
>> The low capacitance, high voltage disc-ceramics sometimes used for
>> flyback tuning in TV LOPT stage have been known to fail, ut its usually
>> visible.
>>
>> Sometimes the ceramic disc cracks and is usually visible because the
>> resin dip also cracks with it, sometimes they track around the edge of
>> the ceramic disc and burn a little "volcano" through the coating.
>>
>
> Yes, that's the type of cap that it is, and those modes of failure are my
> experience of them also. These show no signs of anything like that, and
> check ok for leakage - although not actually tested for this at high
> voltage - and capacitance.
>
> Arfa

They sometimes get very hot and discolour, that probably means either a
fault causing RF noise going into the snubber or sometimes bad design.

== 3 of 4 ==
Date: Sat, Oct 22 2011 12:48 pm
From: "petrus bitbyter"

"Arfa Daily" <arfa.daily@ntlworld.com> schreef in bericht
news:zDooq.16012$tk5.4043@newsfe13.ams2...
>
>>>>
>>>>
>>
>> Didn't you walk right into the problem? It seems that by a yet unknown
>> cause the circuit sometimes runs into some state that makes it oscillate
>> or in some other way fries the resistors. This kind of intermitted faults
>> are the most difficult to solve as most of the times there seems to be no
>> problem. Even your observations with the scope may mislead you as
>> connecting the probe may change the circuit enough to change its
>> behavior.
>>
>> petrus bitbyter
>>
>
> Yes, there may indeed be some kind of intermittent problem. I will put
> them all back up again on Monday, and see how they perform this time. As
> to my 'scope muddying the waters, it's generally pretty well behaved in
> that respect. It's a high quality 100 MHz job, which is always used with a
> x 10 low capacitance probe. If that is having much of an effect on the
> circuit, then it must for sure be a pretty poor design. To be honest, I
> still think that the problem lies with me somehow. Something that I did
> differently between the first and second times that I tried them, but I'm
> not sure what ...
>
> Arfa

Off course you may have made a mistake. Humans make mistakes, even I
sometimes do :)
But if so, what on earth fried those resistors the first time?

petrus bitbyter

== 4 of 4 ==
Date: Sat, Oct 22 2011 10:14 pm
From: josephkk

On Sat, 22 Oct 2011 13:25:36 +0100, "Ian Field"
<gangprobing.alien@ntlworld.com> wrote:

>
>"Phil Allison" <phil_a@tpg.com.au> wrote in message
>news:9geii5F9l4U1@mid.individual.net...
>>
>> "Arfa Daily"
>>
>>
>> ** Get utterly fucked
>>
>> - you stupid, bullshitting, pommy TROLL
>
>
>Missing your dingo mommy & daddy?
>

They disowned him for gloriously obvious reasons.

>=P

==============================================================================
TOPIC: computer problems
http://groups.google.com/group/sci.electronics.repair/t/d5b26a3411c63324?hl=en
==============================================================================

== 1 of 3 ==
Date: Sat, Oct 22 2011 7:06 am
From: "William Sommerwerck"

> However, I have to ask seriously did you read the OP?

Yes. That's why I took so long to respond. I was thoroughly confused.

>: And if I did follow what you just suggested how would that
> have prevented a CMOS virus, if that's what this problem is?

I don't know. But simply attaching an "infected" hard drive to a running
computer won't necessarily spread the infection.

== 2 of 3 ==
Date: Sat, Oct 22 2011 7:09 am
From: "William Sommerwerck"

<stratus46@yahoo.com> wrote in message
news:f64e3ca2-0e7c-45a4-ae65-774ecd54cf79@v1g2000yqn.googlegroups.com...

> What William suggests is something I and many others have done many
times without problems. I saw a computer (not mine) that was so
infected the processor was 100% busy and would do nothing useful,
including running a virus scan. Of course they needed to salvage the
apps and data and couldn't just re-format and start over. The drive
was first slaved into a good machine and subjected to a virus scan.
Remember those pesky viruses have to execute to become active.

Exactly.

> The slave drive executes nothing during boot so activates nothing (unless
the boot drive has its own viruses). That's when I became convinced
about Norton utilities. Norton wouldn't dump a virus because it was
running. AHAH, I'll boot into safe mode and kill it before it's
running. Norton (at least that version) will not run in safe mode. I
don't have Norton.

I did something similar when my main drive became infected seven years ago.
I bought another drive, installed a vanilla version of the OS on it, from
which I probed to infected drive to clean it up.

== 3 of 3 ==
Date: Sat, Oct 22 2011 10:40 am
From: stratus46@yahoo.com

On Oct 22, 7:09 am, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:
<snip>
> I did something similar when my main drive became infected seven
years ago.
> I bought another drive, installed a vanilla version of the OS on
it, from
> which I probed to infected drive to clean it up.

I just had one of those 'DOH' moments. Since the OP just wants to
verify the drives, why not use something like Seagate diagnostics to
boot off of CD and test the drives.If the boot good drive is a Seagate
I don't think it matters what the brand of the test drive is. I expect
WD has something similar. That way he gets a report on the state of
the drive without infecting anything.

G²

==============================================================================
TOPIC: Wanted CCFL tube for 22 inch widescreen LCD
http://groups.google.com/group/sci.electronics.repair/t/ee497293d388f924?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, Oct 22 2011 9:06 am
From: Clyde

On 20/10/2011 20:50, Baron wrote:
> Clyde Inscribed thus:
>
>> Hi, fixing this for a friend. TV is a cheapo Argos (Wharfedale) 22
>> inch widescreen. One of the backlights has failed, causing the
>> inverter to shut off after a few seconds. Confirmed failed lamp using
>> a spare CCFL tube I have laying around. LCD panel (Samsung) has 4
>> tubes, 2 at the bottom and 2 at the top. Tube measures 480mm end to
>> end. Wires are very closely soldered to the tube ends. Has anyone got
>> any laying around, perhaps on a broken screen? Or where would be a
>> good place to get one (UK)
>>
>> I can pick one up online, but they seem to have longer ends for the
>> wire connections, so we would probably have to get one with wires
>> presoldered on, or go for one slightly shorter.
>>
>> Getting the panel apart to gain access to the tubes was fun, I expect
>> even more fun putting it back together and trying to keep it clean.
>> Probably not really designed to be opened up, but the LCD itself is
>> good.
>
> Where abouts in the UK ? I may be able to help...
>
>

Hi Baron I'm in Liverpool

== 2 of 2 ==
Date: Sat, Oct 22 2011 12:11 pm
From: Baron

Clyde Inscribed thus:

> On 20/10/2011 20:50, Baron wrote:
>> Clyde Inscribed thus:
>>
>>> Hi, fixing this for a friend. TV is a cheapo Argos (Wharfedale) 22
>>> inch widescreen. One of the backlights has failed, causing the
>>> inverter to shut off after a few seconds. Confirmed failed lamp
>>> using a spare CCFL tube I have laying around. LCD panel (Samsung)
>>> has 4 tubes, 2 at the bottom and 2 at the top. Tube measures 480mm
>>> end to end. Wires are very closely soldered to the tube ends. Has
>>> anyone got any laying around, perhaps on a broken screen? Or where
>>> would be a good place to get one (UK)
>>>
>>> I can pick one up online, but they seem to have longer ends for the
>>> wire connections, so we would probably have to get one with wires
>>> presoldered on, or go for one slightly shorter.
>>>
>>> Getting the panel apart to gain access to the tubes was fun, I
>>> expect even more fun putting it back together and trying to keep it
>>> clean. Probably not really designed to be opened up, but the LCD
>>> itself is good.
>>
>> Where abouts in the UK ? I may be able to help...
>>
>>
>
> Hi Baron I'm in Liverpool

Ahh ! A bit too far west of me. Wrong end of M62.
Anyway I have spare tubes and screens.
Email me...

--
Best Regards:
Baron.

==============================================================================
TOPIC: A cordless phone question
http://groups.google.com/group/sci.electronics.repair/t/dbf17b88cb06d8a8?hl=en
==============================================================================

== 1 of 4 ==
Date: Sat, Oct 22 2011 9:56 am
From: Ken

I have two AT&T model 1475 cordless phones. (I know they are quite
old, but I like the feel of the phone even though it is a 2.4GHZ phone.)
I acquired the second one for a few dollars primarily for parts if the
first one crapped out. Both of the units work just fine in all respects.

Since they are the same model and the phone from one does NOT work on
the other base unit, I assume there is a different frequency that each
is running at. I opened up one unit and I did notice a crystal tacked
on the back of the PWB that I assume is unique for each pair.

My question: Just out of curiosity, what do the manufacturers do to
make their same model cordless phone communicate with only the base it
belongs? My guess is they change something simple like the crystal on
both the base and handset so that there is a distinction between units.
Anyone know?? Thanks.

== 2 of 4 ==
Date: Sat, Oct 22 2011 12:24 pm
From: "Geoffrey S. Mendelson"

Ken wrote:

> My question: Just out of curiosity, what do the manufacturers do to
> make their same model cordless phone communicate with only the base it
> belongs? My guess is they change something simple like the crystal on
> both the base and handset so that there is a distinction between units.
> Anyone know?? Thanks.

The early ones used different frequencies. Then when the multiple channel units
came out (in the early 1990's) they added some sort of digital encoding to the
signal (such as a low level digital subcarrier) to identify one base station
from another.

Some of the earlier phones had switches inside to set this, later ones were
just hard coded in a ROM somewhere or with soldered jumpers on the boards.

The digital ones just include it in the digital data stream.

Generally they are designed NOT to allow to change them so that you buy a
new one when the old one dies.

The new generation of cordless phones, DECT (there are similar but not
compatible DCT phones) are IMHO best. DECT phones are wifi friendly they
operate in a different band (1.8gHz) and listen to make sure a frequency
is NOT in use by someone else before they transmit.

They also have the ability to connect multiple handsets to the same
base station and some have the ability to roam handests between multiple
base stations.

Geoff.

--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(

== 3 of 4 ==
Date: Sat, Oct 22 2011 12:31 pm
From: Rich Webb

On Sat, 22 Oct 2011 11:56:39 -0500, Ken <Ken@invalid.com> wrote:

> I have two AT&T model 1475 cordless phones. (I know they are quite
>old, but I like the feel of the phone even though it is a 2.4GHZ phone.)
> I acquired the second one for a few dollars primarily for parts if the
>first one crapped out. Both of the units work just fine in all respects.
>
> Since they are the same model and the phone from one does NOT work on
>the other base unit, I assume there is a different frequency that each
>is running at. I opened up one unit and I did notice a crystal tacked
>on the back of the PWB that I assume is unique for each pair.
>
> My question: Just out of curiosity, what do the manufacturers do to
>make their same model cordless phone communicate with only the base it
>belongs? My guess is they change something simple like the crystal on
>both the base and handset so that there is a distinction between units.
> Anyone know?? Thanks.

It's almost certainly handled in the digital realm rather than a single
change in the base frequency. The handset and base are paired together
by something like both sharing the same seed value for a pseudo-random
number generator. The PRN is used as the basis of digital spectrum
spreading of the RF signal, frequency hopping or direct sequence, so
that only units that share the same sequence can inter-operate.

Some base units and handsets can be "registered" together so that the
base can operate with more than one handset. Since that capability isn't
mentioned in the 1475's manual, I'd guess that the pairing is done once,
at the factory.

*If* the pairing key in the handset is stored in an identifiable chip,
say, a serial EEPROM, then it might be possible to get at the key and
change it.

--
Rich Webb Norfolk, VA

== 4 of 4 ==
Date: Sat, Oct 22 2011 12:58 pm
From: Winston

Ken wrote:
> I have two AT&T model 1475 cordless phones.

(...)

> My question: Just out of curiosity, what do the manufacturers do to make
> their same model cordless phone communicate with only the base it
> belongs?

(...)

I don't know, but I RTFM and this seems likely:

See page 36 of:
http://dl.owneriq.net/5/52d44f17-e87a-46c2-adaf-59da932f7357.pdf

Place your new-to-you base unit into a carton
and tape securely closed. Do not touch it
for about a week.

Unplug the power from your existing base unit.
Count to five slowly.

Take the battery out of the new-to-you handset,
count to five slowly and then put it back in.

Place your new-to-you handset onto your base unit
and plug the base unit power back in.

This will cause the unit to reinitialize (and
probably pair your new-to-you handset to your
base unit).

Test your old handset to see that it still works.

If this doesn't work try:
www.telephones.att.com, or call 1 800 222–3111.

--Winston

==============================================================================
TOPIC: O2 Joggler power supply voltage and wattage ?
http://groups.google.com/group/sci.electronics.repair/t/46d63938d1736d01?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, Oct 22 2011 12:45 pm
From: "fynnashba@yahoo.com"

Hi I'm looking for a PSU for a lost O2 joggler. I will need the
voltage and current. Thanks

== 2 of 2 ==
Date: Sat, Oct 22 2011 2:08 pm
From: Archon

On 10/22/2011 3:45 PM, fynnashba@yahoo.com wrote:
> Hi I'm looking for a PSU for a lost O2 joggler. I will need the
> voltage and current. Thanks

5V 400mA according to
http://en.wikipedia.org/wiki/O2_Joggler
JC

==============================================================================
TOPIC: Emerson Clock Radio Model CK5235
http://groups.google.com/group/sci.electronics.repair/t/78605b0d7e63fa5c?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, Oct 22 2011 3:21 pm
From: nucleus

am seeking a schematic for subject clock radio; does anyone have
one or a link? thanks.

==============================================================================
TOPIC: Re-winding solenoids.
http://groups.google.com/group/sci.electronics.repair/t/fd7d7813745e3da8?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, Oct 22 2011 9:55 pm
From: josephkk

On Fri, 21 Oct 2011 05:22:39 -0500, Jeffrey Angus <grendelair@aim.com>
wrote:

>On 10/20/2011 9:51 PM, josephkk wrote:
>> Just for grins, Jeff 1.0 have you tried spice models of the rectifier
>> solenoid at 480 and 240? It may help you see something you may have
>> missed.
>
>It hadn't occurred to me to do that. It's pretty much of a static
>operation. You apply power, it pulls up on the armature. When the
>mechanism changes position, an auxiliary switch disconnects the
>solenoid.

I expect you can learn interesting things looking at the current waveforms
in the various configurations.

>
>> BTW i expect you will replace the bridge with one appropriated
>> rated for the solenoid?
>
>The original bridge was dealing with 480 vac @ 5.2 amps. The new
>coil will present a load of about 4 amps @ 240 vac. It's not an
>issue.

That does not make sense for the ampere-turns argument. The number of
turns drops dramatically thus the current must increase accordingly.

>
>Jeff-1.0

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