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

sci.electronics.repair@googlegroups.com

Today's topics:

* Does this T-Mobile/LG smartphone carrier unlock code ever expire? - 9
messages, 7 authors
http://groups.google.com/group/sci.electronics.repair/t/4272d6a61f9f8866?hl=en
* Phase Linear 400 output transistors - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/d0cb28fa4ada674c?hl=en
* ATX power supply capacitor identification. - 4 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/fb67dd39f9c3abcc?hl=en
* 75 ohm Termination Question - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/be000fe11979bff2?hl=en
* Thomson DSI8210CSR Sky box. - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/9eb327996347968a?hl=en
* Do remote keypads sweat silcone oil? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/c14d8e962b605e97?hl=en
* Magnetic door holders question - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/21eb21515055e1fe?hl=en
* Truth brand electrolytic capacitors - 4 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/024736b296c3838f?hl=en
* Fuse for motor protection? - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/4aa544fb8b4b8aa0?hl=en

==============================================================================
TOPIC: Does this T-Mobile/LG smartphone carrier unlock code ever expire?
http://groups.google.com/group/sci.electronics.repair/t/4272d6a61f9f8866?hl=en
==============================================================================

== 1 of 9 ==
Date: Sat, Feb 15 2014 10:19 pm
From: "Geoffrey S. Mendelson"


Bert wrote:
>
> Unlock codes are specific to the phone. If one worked for all phones, do
> you think people would go to such trouble to get one?
>
They are actually specific not only to the phone, but to the service
provider. So if you bought the phone from T-Mobile, it would have a different
code than the same phone bought from AT&T.

Some phones can be unlocked by buying the code from various vendors in
Eastern Europe. I have unlocked several Motorola phones that way.

Some phones require the code come from the service provider, who will only
provide them to current customers and may have other restrictions.

iPhones really need to be unlocked by Apple, who will only do it if the
service provider who bought it from them asks them to do it. Then a
magical unlock code is sent via iTunes to the registered owner of the phone.

There are many unlock hacks for iPhones, most of them don't work, or stop
working if you reboot the phone.

Geoff.



--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379





== 2 of 9 ==
Date: Sun, Feb 16 2014 12:27 am
From: tlvp


On Sun, 16 Feb 2014 06:19:21 +0000 (UTC), Geoffrey S. Mendelson commented
on:

>> Unlock codes are specific to the phone. If one worked for all phones, do
>> you think people would go to such trouble to get one?
>>
> They are actually specific not only to the phone, but to the service
> provider. So if you bought the phone from T-Mobile, it would have a different
> code than the same phone bought from AT&T.

More particularly, an unlock code is specific to a given handset's IMEI.
The manufacturers leave it, in part, to the service providers to determine
to whom and under what circumstances to reveal the unlock code and
directions for its use. But "service provider" is not used so restrictively
as to mean cellular operators only, for, as you say,

> Some phones can be unlocked by buying the code from various vendors in
> Eastern Europe. I have unlocked several Motorola phones that way.

Mainly, it means Nokia or Motorola won't divulge unlock codes to you or me.
Or anyway, that's the impression I've always been under :-) .

Cheers, -- tlvp
--
Avant de repondre, jeter la poubelle, SVP.




== 3 of 9 ==
Date: Sun, Feb 16 2014 12:48 am
From: Machiel de Wit


Anthony R. Gold schreef op 16-02-2014
in <gotvf9d5gstbi1nb32v49t7koofqo96tdb@4ax.com>:
> On Sat, 15 Feb 2014 23:42:59 +0100, Machiel de Wit
> <reply-to-ng.machiel.dewit@xs4all.nl> wrote:
>
>> Judy Miller schreef op 15-02-2014
>> in <ldoo9l$870$1@speranza.aioe.org>:
>>> Do carrier unlock codes expire?
>>>
>>> I received the message below from T-Mobile containing
>>> the procedure to unlock my kid's cellphone.
>>>
>>> I can email that procedure to the kid, who is away for a
>>> few months, but the kid sometimes messes things up, and it
>>> says that you can destroy the phone if you do it wrong.
>>>
>>> If I wait, the kid will be back in a few months.
>>>
>>> Do you know if these carrier unlock instructions expire?
>>>
>>> ------------------------------------------------------
>>> FROM: AR Notification <DoNotReply@T-Mobile.com>
>>> SUBJECT: T-Mobile Sim Unlock Notification 2125688898
>>> T-Mobile Sim Unlock Request
>>> Sim Unlock Reference: xxxxxxxx
>>> IMEI: xxxxxxxxxxxxx
>>>
>>> Unlock Code: xxxxxxxxxxxxxxx
>>>
>>> Thank you for taking the time to contact T-Mobile.
>>> Below you will see the Instructions for unlocking your LG
>>> device.
>>>
>>> NOTE: If you receive an error message while performing the
>>> instructions below, stop. Please be aware that if an excessive
>>> amount of incorrect attempts are made, the phone will be
>>> permanently locked.
>>>
>>> 1. Insert T-Mobile or Non T-Mobile SIM card in to the device.
>>> 2. Tap the Dialer
>>> 3. Enter 2945#*659#
>>> 4. Selct Network Lock
>>> 5. Enter in the unlock code
>>> 7. Click done
>>> 8. Click unlock
>>>
>>> The phone should display "Network Unlock"
>>> Thank You,
>>> Customer Service
>>> T-Mobile USA, Inc.
>>
>> Are you serious? Then you better cancel your message.
>> Not only never expires de unlock code, you make it posible to kidnap
>> it, due sending all the codes free into the whole world.
>
> Judy, relax. Yes, the unlock code will not expire but also it can not
> be used or abused to kidnap anyone or anything.

The unlock code alone not indeed, but the IMEI code is a unique
identifier.
But who take care these days for personal securyty? One gives
everything away for a free lunch [1]. Apparently Judy is not aware of
the transparency of usenet.

[1] "There ain't no such thing as a free lunch"


--
MdW.




== 4 of 9 ==
Date: Sun, Feb 16 2014 5:05 am
From: Olaf Schmitt


Am 15.02.2014 23:04, schrieb Judy Miller:
> Do carrier unlock codes expire?
>
> I received the message below from T-Mobile containing
> the procedure to unlock my kid's cellphone.
>
> I can email that procedure to the kid, who is away for a
> few months, but the kid sometimes messes things up, and it
> says that you can destroy the phone if you do it wrong.
>
> If I wait, the kid will be back in a few months.
>
> Do you know if these carrier unlock instructions expire?
>
> ------------------------------------------------------
> FROM: AR Notification <DoNotReply@T-Mobile.com>
> SUBJECT: T-Mobile Sim Unlock Notification 2125688898
> T-Mobile Sim Unlock Request
> Sim Unlock Reference: 6493322
> IMEI: 023447039850033
>
> Unlock Code: 5398328494192082
>
> Thank you for taking the time to contact T-Mobile.
> Below you will see the Instructions for unlocking your LG device.
>
> NOTE: If you receive an error message while performing the instructions
> below, stop. Please be aware that if an excessive amount of incorrect
> attempts are made, the phone will be permanently locked.
>
> 1. Insert T-Mobile or Non T-Mobile SIM card in to the device.
> 2. Tap the Dialer
> 3. Enter 2945#*659#
> 4. Selct Network Lock
> 5. Enter in the unlock code
> 7. Click done
> 8. Click unlock
>
> The phone should display "Network Unlock"
> Thank You,
> Customer Service
> T-Mobile USA, Inc.
>

Look at this:
http://www.youtube.com/watch?v=4mndv4gmYEI







== 5 of 9 ==
Date: Sun, Feb 16 2014 2:16 pm
From: "Anthony R. Gold"


On Sun, 16 Feb 2014 09:48:28 +0100, Machiel de Wit
<reply-to-ng.machiel.dewit@xs4all.nl> wrote:

> Anthony R. Gold schreef op 16-02-2014
> in <gotvf9d5gstbi1nb32v49t7koofqo96tdb@4ax.com>:
>> On Sat, 15 Feb 2014 23:42:59 +0100, Machiel de Wit
>> <reply-to-ng.machiel.dewit@xs4all.nl> wrote:
>>
>>> Judy Miller schreef op 15-02-2014
>>> in <ldoo9l$870$1@speranza.aioe.org>:
>>>> Do carrier unlock codes expire?
>>>>
>>>> I received the message below from T-Mobile containing
>>>> the procedure to unlock my kid's cellphone.
>>>>
>>>> I can email that procedure to the kid, who is away for a
>>>> few months, but the kid sometimes messes things up, and it
>>>> says that you can destroy the phone if you do it wrong.
>>>>
>>>> If I wait, the kid will be back in a few months.
>>>>
>>>> Do you know if these carrier unlock instructions expire?
>>>>
>>>> ------------------------------------------------------
>>>> FROM: AR Notification <DoNotReply@T-Mobile.com>
>>>> SUBJECT: T-Mobile Sim Unlock Notification 2125688898
>>>> T-Mobile Sim Unlock Request
>>>> Sim Unlock Reference: xxxxxxxx
>>>> IMEI: xxxxxxxxxxxxx
>>>>
>>>> Unlock Code: xxxxxxxxxxxxxxx
>>>>
>>>> Thank you for taking the time to contact T-Mobile.
>>>> Below you will see the Instructions for unlocking your LG
>>>> device.
>>>>
>>>> NOTE: If you receive an error message while performing the
>>>> instructions below, stop. Please be aware that if an excessive
>>>> amount of incorrect attempts are made, the phone will be
>>>> permanently locked.
>>>>
>>>> 1. Insert T-Mobile or Non T-Mobile SIM card in to the device.
>>>> 2. Tap the Dialer
>>>> 3. Enter 2945#*659#
>>>> 4. Selct Network Lock
>>>> 5. Enter in the unlock code
>>>> 7. Click done
>>>> 8. Click unlock
>>>>
>>>> The phone should display "Network Unlock"
>>>> Thank You,
>>>> Customer Service
>>>> T-Mobile USA, Inc.
>>>
>>> Are you serious? Then you better cancel your message.
>>> Not only never expires de unlock code, you make it posible to kidnap
>>> it, due sending all the codes free into the whole world.
>>
>> Judy, relax. Yes, the unlock code will not expire but also it can not
>> be used or abused to kidnap anyone or anything.
>
> The unlock code alone not indeed, but the IMEI code is a unique
> identifier.
> But who take care these days for personal securyty? One gives
> everything away for a free lunch [1]. Apparently Judy is not aware of
> the transparency of usenet.
>
> [1] "There ain't no such thing as a free lunch"

I still have no idea what you are warning about. Please be specific about
what harm anyone can do to Judy by knowing both that unlock code and her
phone's IMEI number. Because some number is unique does not make it valuable
to anyone else who is seeking to do mischief. The Message-Id of your last
post was <53007b5d$0$2966$e4fe514c@news2.news.xs4all.nl>, which is unique,
and that knowledge plus $3.65 will buy me a Grande Latte at Starbucks.




== 6 of 9 ==
Date: Sun, Feb 16 2014 3:20 pm
From: "Maynard A. Philbrook Jr."


In article <5od2g91lno1msbl75srd637g1gtr0j0qt5@4ax.com>, not-for-
mail@ahjg.co.uk says...
> > [1] "There ain't no such thing as a free lunch"
>
> I still have no idea what you are warning about. Please be specific about
> what harm anyone can do to Judy by knowing both that unlock code and her
> phone's IMEI number. Because some number is unique does not make it valuable
> to anyone else who is seeking to do mischief. The Message-Id of your last
> post was <53007b5d$0$2966$e4fe514c@news2.news.xs4all.nl>, which is unique,
> and that knowledge plus $3.65 will buy me a Grande Latte at Starbucks.
>

How much does it cost me with out the knowledge coupon?


Jamie






== 7 of 9 ==
Date: Sun, Feb 16 2014 4:21 pm
From: "Anthony R. Gold"


On Sun, 16 Feb 2014 18:20:40 -0500, "Maynard A. Philbrook Jr."
<jamie_ka1lpa@charter.net> wrote:

> In article <5od2g91lno1msbl75srd637g1gtr0j0qt5@4ax.com>, not-for-
> mail@ahjg.co.uk says...
>>> [1] "There ain't no such thing as a free lunch"
>>
>> I still have no idea what you are warning about. Please be specific about
>> what harm anyone can do to Judy by knowing both that unlock code and her
>> phone's IMEI number. Because some number is unique does not make it valuable
>> to anyone else who is seeking to do mischief. The Message-Id of your last
>> post was <53007b5d$0$2966$e4fe514c@news2.news.xs4all.nl>, which is unique,
>> and that knowledge plus $3.65 will buy me a Grande Latte at Starbucks.
>>
>
> How much does it cost me with out the knowledge coupon?

$3.65




== 8 of 9 ==
Date: Sun, Feb 16 2014 6:20 pm
From: "Maynard A. Philbrook Jr."


In article <dgl2g9d1j36n8le9qlms5knqlvbl3ch0gm@4ax.com>, not-for-
mail@ahjg.co.uk says...
>
> On Sun, 16 Feb 2014 18:20:40 -0500, "Maynard A. Philbrook Jr."
> <jamie_ka1lpa@charter.net> wrote:
>
> > In article <5od2g91lno1msbl75srd637g1gtr0j0qt5@4ax.com>, not-for-
> > mail@ahjg.co.uk says...
> >>> [1] "There ain't no such thing as a free lunch"
> >>
> >> I still have no idea what you are warning about. Please be specific about
> >> what harm anyone can do to Judy by knowing both that unlock code and her
> >> phone's IMEI number. Because some number is unique does not make it valuable
> >> to anyone else who is seeking to do mischief. The Message-Id of your last
> >> post was <53007b5d$0$2966$e4fe514c@news2.news.xs4all.nl>, which is unique,
> >> and that knowledge plus $3.65 will buy me a Grande Latte at Starbucks.
> >>
> >
> > How much does it cost me with out the knowledge coupon?
>
> $3.65

Ok, so any retard can get a coffee at starbucks!

:_
Jamie





== 9 of 9 ==
Date: Sun, Feb 16 2014 9:24 pm
From: gordonb.gf7gp@burditt.org (Gordon Burditt)


> I still have no idea what you are warning about. Please be specific about
> what harm anyone can do to Judy by knowing both that unlock code and her
> phone's IMEI number.

I think it is possible to track the phone's movements (provided
it's on) knowing the IMEI number. This works in two situations:
(1) you have a friend at the phone's cellular provider who has
access to cell phone tower data. However, if he's got
access to the tower data, he can probably do a phone-number-to-IMEI
lookup or customer-name-to-IMEI lookup just as easily.
and
(2) you are close enough to the phone to receive the signal directly,
with a "direction-finder" like device. Possibly it could
work better by pretending to be a cell phone tower and
getting the phone to respond to it. I don't know how common
these devices are, but I think law enforcement has them.

I think the unlock code is pretty useless, with or without the
IMEI number, unless you own the phone or plan to steal it.

> Because some number is unique does not make it valuable
> to anyone else who is seeking to do mischief.

A remotely readable unique number (e.g. cell phone IMEI numbers,
RFID tags (in, say, credit cards, clothes, etc.), toll tags, Bluetooth
MAC addresses, WiFi MAC addresses, etc. tend to be more abusable
in two ways: tracking/stalking someone, and spending their money.

The longer the range and the more related to money it is, the more
abusable it is. IMEI numbers are pretty long-range (I suspect
providers can do a network-wide international search, although the
radio signal probably reaches only a few nearby cell towers) for
tracking but don't seem to have much potential for financial abuse.
(At least on T-Mobile, the SIM card, not the IMEI, seems to provide
the billing info).

Credit cards with RFID chips may be readable for only a few feet,
making them not so good for location tracking, but the financial
abuse (and mistake) potential is enormous. I've witnessed two
people using Mobil SpeedPass accidentally pay for each other's gas,
then almost drive off before one of them noticed the problem (my
Toyota can't possibly hold 80 gallons of gas!).






==============================================================================
TOPIC: Phase Linear 400 output transistors
http://groups.google.com/group/sci.electronics.repair/t/d0cb28fa4ada674c?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, Feb 15 2014 11:26 pm
From: "Phil Allison"



<jurb6006@gmail.com>

>"** It does if you mix up devices. "

Not much. In each bank you got the bases all connnected directly together
and the emitters are only separated by 0.33 resistors.

** If you have 3 of one kind on one side, then 10 ohms drops to 7 and the
pre bias is skewed.


>"** The relay contacts will arc and burn soon as they open under a DC
>fault. "

Well now I got a solution to that believe it or not and I am surprised that
noone does it. (or maybe they do)
take a nice 47 uF or so bipolar cap across the contacts. Period. think
aabout it no before to go saying anything.

** Far cheaper to use a triac, DC crowbar to protect speakers.

OR a changeover relay wired to open the output link PLUS short the speakers
to ground under DC fault conditions.

Must have installed 50 of those in PL400s and PL700s years ago.



... Phil










==============================================================================
TOPIC: ATX power supply capacitor identification.
http://groups.google.com/group/sci.electronics.repair/t/fb67dd39f9c3abcc?hl=en
==============================================================================

== 1 of 4 ==
Date: Sat, Feb 15 2014 11:45 pm
From: "Phil Allison"



<jurb6006@gmail.com>
Our buddy Phill composed, in an unusually non-berating way today thusly :

>"Large electros kill spikes just like sledgehammers kill flies. "

And they got better aim. As long as you have full wave rectification, and
the rectifiers can handle alot of peak current, they are quite effective.
However they are not effective so much against having simple overvoltage
applied.

You are not in the US, if the power there is like the UK or whatever it is
different. While you have 240 coming in referenced to neutral, in the US it
is half that. The line is balanced with two 120 volt legs out of phase.
Almost all smaller appliiances run from one leg to neutral. If the neutral
loses continuity it can apply as much as double the effective, peak to peak,
RMS and whatever other way you want to measure it - voltage to your
appliance.


** The 120V leg with the greater load will drop voltage when the neutral is
lost - so the other leg goes up until something goes bang.

This cannot happen in the good countries but I am not here to bitch.

** It happens now and then in live entertainment venues when 3 phase power
is used.

Same reason, no neutral exists or loss of the of neutral conductor.


.... Phil






== 2 of 4 ==
Date: Sun, Feb 16 2014 1:03 am
From: "Michael A. Terrell"



jurb6006@gmail.com wrote:
>
> I think as soon as Edison's body was cold they should have made it 240, yes center tapped like it is, but made all the outlets and appliances 240 all the time. they also should have changed the frequency to 400 Hz. (CPS LOL) Or better yet, maybe 360 or something to make it easier to make electric clocks. Synchronous motors would be a little more complex but think of all the speeds you could have.


You are already too drunk to make sense. There were a lot of 25 Hz
power plants for rialroads, mines and other places that required low
speeds and very high starting torque. Also, 400 hz would reduce the size
of a power grid segments, before the losses become excessive. This would
require a lot more HV AC to DC and DC to AC conversion for distribution
between grid segments. That also lowers the overall grid efficiency,
which will raise your electric bill. This is why no one asked your
opinion of our power distribution systems.

<http://en.wikipedia.org/wiki/Amtrak%27s_25_Hz_traction_power_system>


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.




== 3 of 4 ==
Date: Sun, Feb 16 2014 7:34 am
From: Ian Malcolm


"Phil Allison" <phil_a@tpg.com.au> wrote in
news:bmb8ikF12vuU1@mid.individual.net:

>
> <jurb6006@gmail.com>
> Our buddy Phill composed, in an unusually non-berating way today
> thusly :
>
>>"Large electros kill spikes just like sledgehammers kill flies. "
>
> And they got better aim. As long as you have full wave rectification,
> and the rectifiers can handle alot of peak current, they are quite
> effective. However they are not effective so much against having
> simple overvoltage applied.
>
Thanks for the correction. I mistyped, omitting "and surges" as you may
have guessed by my reference to surges later on. However I do wonder
whether the self-inductance of the typical wound foil construction high
voltage electrolytic is enough to cause problems with very short
impulses if one omits the varistors.

Littelfuse's Varistor page (which contains more than yoever wanted to
know about them):
<http://www.littelfuse.com/products/varistors.aspx>
states:


> *** Speed of Response and Rate Effects ***
>
> The varistor action depends on a conduction mechanism similar to that
> of other semiconductor devices. For this reason, conduction occurs
> very rapidly, with no apparent time lag - even into the nanosecond
> (ns) range. Figure 18, shows a composite photograph of two voltage
> traces with and without a varistor inserted in a very low inductance
> impulse generator. The second trace (which is not synchronized with
> the first, but merely superimposed on the oscilloscope screen) shows
> that the voltage clamping effect of the varistor occurs in less than
> 1.0 ns.

It does qualify that by stating this speed is not achivable in a leaded
package, but I'd bet its still far far better than the electrolytics
capability to deal with fast risetime transients.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL




== 4 of 4 ==
Date: Sun, Feb 16 2014 4:15 pm
From: "Phil Allison"



"Ian Malcolm"
> "Phil Allison" >
>>
>>>"Large electros kill spikes just like sledgehammers kill flies. "
>>
>> And they got better aim. As long as you have full wave rectification,
>> and the rectifiers can handle alot of peak current, they are quite
>> effective. However they are not effective so much against having
>> simple overvoltage applied.
>>
> Thanks for the correction. I mistyped, omitting "and surges" as you may
> have guessed by my reference to surges later on. However I do wonder
> whether the self-inductance of the typical wound foil construction high
> voltage electrolytic is enough to cause problems with very short
> impulses if one omits the varistors.


** There is no such " self inductance" with electros or other wound foil
capacitors.

FYI:

The inductance of the PCB traces is far more than that of typical
capacitors.

You are clutching at straws - pal.


.... Phil







==============================================================================
TOPIC: 75 ohm Termination Question
http://groups.google.com/group/sci.electronics.repair/t/be000fe11979bff2?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Feb 16 2014 6:16 am
From: dave


On 02/14/2014 09:03 AM, Jeff Liebermann wrote:
> On Fri, 14 Feb 2014 06:38:54 -0800, dave <ricketzz@earthlink.net>
> wrote:
>
>> On 02/13/2014 06:07 PM, Jeff Liebermann wrote:
>>> On Thu, 13 Feb 2014 17:41:28 -0800, Bennett <bjprice@cal.berkeley.edu>
>>
>>>
>>> Not good enough. If you just crammed a 68 ohm resistor into the
>>> F-connector jack, you probably have a fairly good approximation of an
>>> antenna. It's going to radiate junk, and pickup more junk (ingres).
>>> If you insist on doing it like that, wrap the resistor with some
>>> insulating tape, and then cover it with aluminum foil.
>
>> Do you have any idea what the wavelength is at 600MHz? It's half a meter
>> (Meters times megaHertz equals 300). That makes the length of a quarter
>> wave is 1/8 meter or about 5". A tiny resistor is not going to radiate
>> efficiently enough.
>
> Whether it radiates efficiently or inefficiently, it still radiates.
> Assuming a 1/2 watt resistor, with one lead wrapped around the
> grounding screw, and the other shoved into the F-connector center
> wire, there will be about 1/4" of exposed wire between the center pin
> and the 60 ohm resistor. That's not much, can probably be tolerated,
> and will be sufficient to slightly increase base line noise level in
> the area. I would hate to think what might happen if EVERYONE decided
> to use leaky terminators.[1]
>
> I like to play ham radio (VHF/UHF) in my vehicle when driving. I
> constantly hear the digital hash as I drive repeatedly by specific
> locations. At first, I assumed that these were leaks from the
> overhead cable plant. Nope. When I started banging on doors, I found
> some really creative wiring and connector crimping. Most were caused
> by distribution amps with unterminated cables, where the coax cable
> becomes somewhat of an antenna. I also found either a defective drop
> or tap on the pole (Comcast didn't tell me what they found, but they
> did fix it).
>
> Obviously, a leaky cable is a much longer length of wire than 1/4" of
> exposed center conductor. Yet, after the gross leaks were fixed, I
> still could still hear the test tones on the borrowed Trilithic
> something leakage detector. I had to install terminators on literally
> everything to reduce it to zero. Admittedly, I was working well below
> the FCC Part 76.605 leakage limits:
> <http://transition.fcc.gov/mb/engineering/605.html>
> <http://www.cablefax.com/tech/sections/columns/broadband/Broadband-Signal-Leakage-in-an-All-Digital-Network_33882.html>
> <http://www.cablefax.com/tech/deployment/bestpractices/A-Leak-Is-A-Leak&hellip%20Or-Is-It_52272.html>
> but I needed to get the radiated junk down to a level where I could
> use my radios in the neighborhood. Overkill yes, but necessary.
>
> It's also a problem in the other direction, which is called ingress.
> Nearby transmitters, such as mine, can easily get into the cable
> system, and interfere with reception. Once it gets in, there's no
> easy way to get rid of the signal. The best approach is proper
> shielding. It isn't just my transmitters, but broadcast stations,
> intermod with cordless phones, RF remotes, wireless security cameras,
> and other RF devices. Mostly, they cause problems with cable modems,
> which use the higher RF frequencies, but in extreme cases, can affect
> TV reception. It's also difficult to see with a spectrum analyzer:
> <http://www.jdsu.com/ProductLiterature/DSAM-D3-Spectrum-Analyzer-App-Note.pdf>
> Can you see it? Spoiler:
> <http://blogs.jdsu.com/hfc/Lists/Photos/dd6cc9ceb7e6a11e1006e1ad654edd7f.jpg>
>
> More:
> "Characterizing Signal Leakage from an All-Digital Cable Network"
> <http://www.incospec.com/resources/webinars/files/Characterizing%20Signal%20Leakage%20from%20an%20All-Digital%20Cable%20NetworkMS.pdf>
>
>> If the "splitter" is a hybrid the unterminated port
>> will cause higher attenuation through the splitter. Maybe a single dB.
>> Not important when receiving.
>
> Without a termination, the splitter begins to resonate with the coax
> cable which can be made to radiate. I'm not sure of the unterminated
> losses, but I suspect it's more than 1dB. I'll try it on the bench
> when I have time (mostly to clean off the accumulated junk from the
> bench).
> <http://802.11junk.com/jeffl/pics/home/slides/test-equip-mess.html>
>
>> You'd be better off getting a DC block. The splitter loses at least 3 dB.
>
> A DC block won't do anything useful except block DC. I think you
> might have meant a straight through barrel connector.
>
>
>
> [1] Incidentally, you might be amused to look at my study of monopole
> antenna gains versus length.
> <http://802.11junk.com/jeffl/antennas/Monopole/index.html>
> The title includes the wavelength. For example, 0_750 is 3/4
> wavelength long and 5_250 is 5.25 wavelengths long. If you look at
> the antenna gains, you'll notice that the gain doesn't really drop
> very much for shortened antennas. From the antenna patterns:
> Wavelength Gain dBi
> 0.250 5.19
> 0.125 4.85
> 0.050 4.75
> That's a 0.45dB gain loss in an antenna that's 1/5th the length of a
> 1/4 wave radiator. That might explain why I'm concerned about even
> small amounts of exposed center conductor.
>
>

Here's one kind of splitter:

http://www.e-meca.com/tech_papers/hybrid_basic.php

And another:

http://www.minicircuits.com/pdfs/SEPS-4-272+.pdf

Only the hybrid type leaks a bunch. The port to port isolation of the
second type keeps unterminated ports from radiating.






== 2 of 2 ==
Date: Sun, Feb 16 2014 9:02 am
From: Jeff Liebermann


On Sun, 16 Feb 2014 06:16:31 -0800, dave <ricketzz@earthlink.net>
wrote:


>Here's one kind of splitter:
>http://www.e-meca.com/tech_papers/hybrid_basic.php
>And another:
>http://www.minicircuits.com/pdfs/SEPS-4-272+.pdf

There are several types of 2-way splitters and combiners. Resistive,
0 degree, 90 degree, 180 degree, Wilkinson, DH-P, and whatever else I
forgot, with and without DC pass.

The typical commodity CATV 2-way splitter is a simple bifilar wound,
center tapped, ferrite transformer. There is no 100 ohm resistor
between output ports which is needed to improve isolation. They're
easy enough to open and look inside:
<http://www.cliftonlaboratories.com/userimages/6_db_h22.jpg>
<http://img198.imageshack.us/img198/6017/twoway.jpg>
<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDJbgN317fHk7VxPtnt6nGkU8yLje0kqeS7BDaUQKZyW4vaXQDMgoGr6D2l6TUxAJ3yu8mqgiZIMNVkVlwd6c0SPH1YC1Or-rAbYqCr595Kb8otB1G7d3thGAIOIbt84BGAF1EceHLwBw/s1600/3-way.JPG>
<http://www.waltzking.org/potd/20070124.jpg>
Not every complexicated or impressive.

More:
<http://www.cliftonlaboratories.com/6_db_hybrid_combiner.htm>
Scroll down to "RCA VH476 CATV Splitter" section:

>Only the hybrid type leaks a bunch. The port to port isolation of the
>second type keeps unterminated ports from radiating.

Nope. You misinterpreted the meaning of the port to port isolation
specification. What it means is that if you have all the ports
properly terminated, and you inject a signal into one of the 2
splitter ports, how much of that signal will appear on the other
splitter port.


--
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





==============================================================================
TOPIC: Thomson DSI8210CSR Sky box.
http://groups.google.com/group/sci.electronics.repair/t/9eb327996347968a?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Feb 16 2014 10:57 am
From: "Ian Field"


Does anyone know the sequence to invoke factory defaults?

Where to find the manual would be handy too.

Thanks.





==============================================================================
TOPIC: Do remote keypads sweat silcone oil?
http://groups.google.com/group/sci.electronics.repair/t/c14d8e962b605e97?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Feb 16 2014 3:21 pm
From: Mick Nowell


>> Vinyl seems to emit a gas which will react with and destroy many
>> substances. A good example is those vinyl book covers which have
>> turned the outside of many a book into eternal sticky mush.
>
>It's not a gas, it's the plasticizer that keeps the vinyl flexible. I had the
>same trouble with textbooks that had a kind "plastic-coated-board" covers. And
>I've seen the plasticizer in patch cords attack plastic surfaces.
>
>I am no aware of any plasticizer in the rubbery contacts of remote controls.
>
>I've taken apart the keypad for my Ford. There is a silicone goo in it, which
>I assume is there to prevent rust or corrosion.


Similar problem with paint on guitars. Stands containing certain foam
protection or vinyl hooks don't do well with enamel necks.





==============================================================================
TOPIC: Magnetic door holders question
http://groups.google.com/group/sci.electronics.repair/t/21eb21515055e1fe?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Feb 16 2014 3:33 pm
From: Mick Nowell


>I work on commercial fire alarm systems mostly in apartment houses. Many of these buildings in the common hallways employ electromagnetic units mounted on the walls and an iron disk on the back corner of the doors. When the doors are opened and the disks are mated with the electromagnet the doors are held open in place. These doors all have pneumatic closers on them as well which are always applying a force in the opposite direction to try to close the door.
>
>When the alarm is activated the 24VDC is removed from the coils and the doors are supposed to be automatically pulled closed by the force of the pneumatic unit. This doesn't always work because in spite of the opposing force applied by the pneumatic unit, in many cases the electromagnets seem to hold enough residual magnetism to keep disks from releasing and the doors from closing. It often becomes necessary to increase the opposing pneumatic force tremendously in order to overcome this.
>
>I have discussed this with various manufacturers of these electromagnetic units and in all but one instance have received the same bullshit answer that they've "never heard of this".
>
>The one exception was one tech who ventured that perhaps momentarily reversing polarity on alarm before DC drop out might work, however he had never tried it. Does anyone have any ideas about this? Thanks, Lenny

Disconnect the PU from the door. Get a scale and see how much force it
takes to open each unit.
Before any modification I suggest exercising them. Pop each one open
and "brillo" the oxidization/whatever on each surface. Repeat.





==============================================================================
TOPIC: Truth brand electrolytic capacitors
http://groups.google.com/group/sci.electronics.repair/t/024736b296c3838f?hl=en
==============================================================================

== 1 of 4 ==
Date: Sun, Feb 16 2014 6:36 pm
From: Jeff Liebermann


<http://wtfmoogle.com/?p=3585>
Now, there is something I haven't seen before. Electrolytics that
bulge and leak goo without any applied voltage. Probably useful for
ultra-short product warranties.

--
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 4 ==
Date: Sun, Feb 16 2014 10:29 pm
From: John Robertson


On 02/16/2014 6:36 PM, Jeff Liebermann wrote:
> <http://wtfmoogle.com/?p=3585>
> Now, there is something I haven't seen before. Electrolytics that
> bulge and leak goo without any applied voltage. Probably useful for
> ultra-short product warranties.
>

I trust they weren't sitting in the sun or some other heat source?

I've seen similar results with NOS computer motherboards where several
caps did the bulge without being powered up for many years...

John :-#(#

--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."




== 3 of 4 ==
Date: Sun, Feb 16 2014 11:34 pm
From: Jeff Liebermann


On Sun, 16 Feb 2014 22:29:05 -0800, John Robertson <spam@flippers.com>
wrote:

>On 02/16/2014 6:36 PM, Jeff Liebermann wrote:
>> <http://wtfmoogle.com/?p=3585>
>> Now, there is something I haven't seen before. Electrolytics that
>> bulge and leak goo without any applied voltage. Probably useful for
>> ultra-short product warranties.

>I trust they weren't sitting in the sun or some other heat source?

They're not my caps, so I don't know the history. They were in a
plastic bin, probably indoors in his "lab". I don't see overheating
as a possible culprit. Heating might have melted the plastic bin
before it affected the capacitors.

>I've seen similar results with NOS computer motherboards where several
>caps did the bulge without being powered up for many years...

I haven't, but I don't stock new motherboards. Note that the
defective Truth caps still have their long leads and have obviously
not been used in any device.

--
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




== 4 of 4 ==
Date: Mon, Feb 17 2014 12:06 am
From: John Robertson


On 02/16/2014 11:34 PM, Jeff Liebermann wrote:
> On Sun, 16 Feb 2014 22:29:05 -0800, John Robertson <spam@flippers.com>
> wrote:
>
>> On 02/16/2014 6:36 PM, Jeff Liebermann wrote:
>>> <http://wtfmoogle.com/?p=3585>
>>> Now, there is something I haven't seen before. Electrolytics that
>>> bulge and leak goo without any applied voltage. Probably useful for
>>> ultra-short product warranties.
>
>> I trust they weren't sitting in the sun or some other heat source?
>
> They're not my caps, so I don't know the history. They were in a
> plastic bin, probably indoors in his "lab". I don't see overheating
> as a possible culprit. Heating might have melted the plastic bin
> before it affected the capacitors.
>
>> I've seen similar results with NOS computer motherboards where several
>> caps did the bulge without being powered up for many years...
>
> I haven't, but I don't stock new motherboards. Note that the
> defective Truth caps still have their long leads and have obviously
> not been used in any device.
>

I had two NOS motherboards (roughly 2005 vintage) shipped to me for
repairing an old KIP scanner/printer computer - it had to have specific
vintage motherboard. The boards had never been used as far as I could
tell (and the company selling to me is reputable), but both boards had
the same bulging caps.

http://ww.flippers.com/images/KIP-MPU-BulgingCap.JPG

http://ww.flippers.com/images/KIP-MPU-BulgingCap2.JPG

http://ww.flippers.com/images/KIP-MPU-BulgingCap3.JPG

John :-#)#

--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."





==============================================================================
TOPIC: Fuse for motor protection?
http://groups.google.com/group/sci.electronics.repair/t/4aa544fb8b4b8aa0?hl=en
==============================================================================

== 1 of 3 ==
Date: Sun, Feb 16 2014 10:23 pm
From: Mike Cook


A small 1/2 hp induction motor is turned on and off with a motor-rated toggle
switch connected to a 208V 20A branch circuit. No other protection installed.


Obviously not enough protection so I'm planning to add a slow-blow 9A fuse
(rating of the motor) to keep it safe.

Any objections?





== 2 of 3 ==
Date: Sun, Feb 16 2014 11:11 pm
From: Mike Cook


> No internal overload protection?

As in a resettable overload button? Don't remember, I'll check. Can you give
me a couple of "what if's"? ("If it does, then..." and "If it doesn't,
then...")

> It won't hurt anything to fuse it but you may be adjusting the fuse
> size.

As in, the 9A may blow quickly and I'll have to adjust upward a little?





== 3 of 3 ==
Date: Sun, Feb 16 2014 11:50 pm
From: Jeff Liebermann


On Sun, 16 Feb 2014 22:23:31 -0800, Mike Cook <mcham@NOTyahoo.com>
wrote:

>A small 1/2 hp induction motor is turned on and off with a motor-rated toggle
>switch connected to a 208V 20A branch circuit. No other protection installed.
>
>
>Obviously not enough protection so I'm planning to add a slow-blow 9A fuse
>(rating of the motor) to keep it safe.
>
>Any objections?

Any reason that you didn't bother to disclose all the important motor
characteristics and details? Single phase or 3 phase? 1725 rpm or
something else? The nameplate of your 1/2 hp motor should specify the
operating current at 208v. What is the nameplate operating current?
Extra credit for the maker and model number.

The problem is that starting current can be 3 to 4 times the nameplate
oprating current. Your common 9A slow blow cartridge fuse isn't going
to work if your motor operates at about 4A.

You have some choices. Try plugging into this calculator and pick the
fuse type (non-time delay, dual element time delay, instant trip, or
inverse time trip) that you find appropriate.
<http://www.electrician2.com/calculators/motor_ver_1.html>

--
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




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