Digest for sci.electronics.repair@googlegroups.com - 19 updates in 4 topics

bruce2bowser@gmail.com: Jul 07 08:28AM -0700

"Science Unlocks Slimming Effects of Spaghetti" by Premack, Rachel. Washington Post July 7, 2016 p.A3
Jeff Liebermann <jeffl@cruzio.com>: Jul 06 09:51AM -0700

On Wed, 6 Jul 2016 12:18:00 -0400, "J.B. Wood"
 
>I've got a call into Verizon on the above but am scratching my head as
>to what might be causing all of this. Your thoughts would be most
>appreciated. Sincerely,
 
At both ends of the 2 wire POTS line is a 2 wire to 4 wire hybrid
circuit, which deals with seperating the audio in both directions
while maintaining full duplex operation. My guess(tm) is that the
receive part of the hybrid circuit at the Verizon end is broken. Not
much you can do to solve the problem at your end.
 
--
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
"J.B. Wood" <arl_123234@hotmail.com>: Jul 06 12:56PM -0400

On 07/06/2016 12:29 PM, mike wrote:
 
> Turned out to be a busted ground wire half a mile away.
> The local ground connection was enough to make the audio
> work, but the broken wire made the other stuff fail.
 
Hello, and interesting. By "ground" do you mean earthed? In the olden
all-analog days IIRC the only connection to earth on a 2 wire phone line
was at the CO where the positive terminal of the 48 volt common battery
was solidly connected to earth. (I'm not including party-line
ringing-to-ground configurations that are decades obsolete.) Sincerely,
 
--
J. B. Wood e-mail: arl_123234@hotmail.com
"J.B. Wood" <arl_123234@hotmail.com>: Jul 06 01:07PM -0400

On 07/06/2016 12:51 PM, Jeff Liebermann wrote:
 
> while maintaining full duplex operation. My guess(tm) is that the
> receive part of the hybrid circuit at the Verizon end is broken. Not
> much you can do to solve the problem at your end.
 
Hello, and that certainly makes sense, assuming we treat the DC current
loop functionally separate from the AC (voice) part. That means voice
frequencies (voice and DTMF tones) generated at my subscriber location
are of insufficient amplitude by the time they reach the CO. But voice
signals from the caller are getting by OK in the other direction. I
believe those phone hybrids used on line repeaters function the same way
as the 3-dB power splitters/combiners that I've used in RF circuits.
Sincerely, and thanks for replying
 
--
J. B. Wood e-mail: arl_123234@hotmail.com
mike <ham789@netzero.net>: Jul 06 01:09PM -0700

On 7/6/2016 9:56 AM, J.B. Wood wrote:
> was at the CO where the positive terminal of the 48 volt common battery
> was solidly connected to earth. (I'm not including party-line
> ringing-to-ground configurations that are decades obsolete.) Sincerely,
 
There are two wires. One is grounded, the other has -48 volts.
If you cut the grounded wire and use a voltmeter to measure
the voltage to ground at the customer end, you measure -48 volts to ground,
but the signal is trying to use one wire and the local ground
path that it could find.
That didn't work for phone, but it did work for DSL,
although I didn't measure the speed or error rate.
I was gonna TDR the line, but was afraid the phone might ring
and blow up my instrument.
The phone guy took a quick look and drove away.
Came back in half an hour and said the ground wire had
been severed down the street.
Wayne Chirnside <faux@notthere.com>: Jul 07 05:05AM

On Wed, 06 Jul 2016 12:18:00 -0400, J.B. Wood wrote:
 
 
> I've got a call into Verizon on the above but am scratching my head as
> to what might be causing all of this. Your thoughts would be most
> appreciated. Sincerely,
 
I experienced precisely the same thing due to corrosion on the
connections at entry causing it to behave as a rectifier.
 
Cleaned up the connection and all was well.
Took me a week to find it.
YMMV
JJ <JJ@AIOESPAM.COM>: Jul 07 07:00AM -0700

If you reverse the pair you get audio but no touchtone action.
 
Also if you use a wonky wall to set cord you get strange behavior.
Tried the cord on other phone and it was good there but not on a
different set. This while AT&T tech stood over me so I know it was not me.
 
Been there done both.
Pat <pat@nospam.us>: Jul 07 10:36AM -0400


>There are two wires. One is grounded, the other has -48 volts.
 
Not true. POTS lines are balanced twisted pairs. Neither side is
supposed to be grounded (except for old party line ringing schemes).
Pat <pat@nospam.us>: Jul 07 10:38AM -0400


>If you reverse the pair you get audio but no touchtone action.
 
Not necessarily true. Old Western Electric touch tone pad required
the correct polarity to generate tones, but most modern equipment has
some sort of bridge rectifier to power the electronics so polarity
doesn't matter.
"Ian Field" <gangprobing.alien@ntlworld.com>: Jul 06 07:46PM +0100

Pretty weird behavior..................................
 
Took a picture yesterday, tried to copy it to HDD and it disappeared without
trace.
 
Took another picture today and checked the boxes so it was copied to folder
with a number added to the name.
 
Today; opened file on the camera and it displays the picture that went
missing yesterday - but any attempt to save it saves a copy of todays
picture.
makolber@yahoo.com: Jul 07 06:59AM -0700

On Wednesday, July 6, 2016 at 2:46:03 PM UTC-4, Ian Field wrote:
 
> Today; opened file on the camera and it displays the picture that went
> missing yesterday - but any attempt to save it saves a copy of todays
> picture.
 
right click the icon and select refresh (or update) thumbnail
 
M
sms <scharf.steven@geemail.com>: Jul 06 12:16PM -0700

On 7/4/2016 7:16 PM, DaveC wrote:
> designs; not all are repairable, IME.
 
> Anyone find a long-term fix, or quality cable that avoids this problem
> altogether?
 
The highest quality cables I've found are the Fujitsu cables.
Unfortunately they are quite expensive, $1.80 each if you buy a lot of
10, once you pay shipping.
 
<http://www.ebay.com/itm/182181176364>
 
These are pretty large diameter cables because they use AWG 22 wire. The
sub-$1 cables use either all AWG 28, or use AWG 28 for D+ and D-, and
AWG 26 for power and ground.
mike <ham789@netzero.net>: Jul 06 12:58PM -0700

On 7/6/2016 12:16 PM, sms wrote:
 
> These are pretty large diameter cables because they use AWG 22 wire. The
> sub-$1 cables use either all AWG 28, or use AWG 28 for D+ and D-, and
> AWG 26 for power and ground.
 
Thanks for the link.
The large plastic on the small end may mean that they're less
susceptible to being torqued sideways in the socket.
DecadentLinuxUserNumeroUno <DLU1@DecadentLinuxUser.org>: Jul 06 04:08PM -0400


>Thanks for the link.
>The large plastic on the small end may mean that they're less
>susceptible to being torqued sideways in the socket.
 
You guys are silly. Cranking on the cable doesn't damage the 'male'
cable, it damages the shroud of the socket you have it in.
mike <ham789@netzero.net>: Jul 06 03:00PM -0700

On 7/6/2016 1:08 PM, DecadentLinuxUserNumeroUno wrote:
>> susceptible to being torqued sideways in the socket.
 
> You guys are silly. Cranking on the cable doesn't damage the 'male'
> cable, it damages the shroud of the socket you have it in.
 
Indeed. It's my contention that the socket is the problem.
Cable plug is easily replaced. Bent/distorted/mangled socket is not.
sms <scharf.steven@geemail.com>: Jul 06 03:39PM -0700

On 7/6/2016 3:00 PM, mike wrote:
>> cable, it damages the shroud of the socket you have it in.
 
> Indeed. It's my contention that the socket is the problem.
> Cable plug is easily replaced. Bent/distorted/mangled socket is not.
 
The pins on the cheap cables lose their springiness and no longer
contact the contacts in the female socket in the phone. It's a good
design since replacement cables are pretty cheap, but changing the
socket on the phone is expensive.
 
I've found that the 79¢ Micro USB cables, i.e.
<http://www.monoprice.com/product?p_id=4867> are significantly poorer
quality than the $1.80 22 AWG cables that I bought. Plus if you're
charging a high current Micro USB device, using a high-current charger,
you need the better cables, though the 26/24 are also fine.
krw@attt.bizz: Jul 06 08:43PM -0400

On Wed, 06 Jul 2016 03:32:37 -0400, DecadentLinuxUserNumeroUno
 
>>AlwaysWrong.
 
> You're a goddamned idiot kiethkeithstain. You are a stain on society.
>And that stench! Go away, old fucktard.
 
You're *always* wrong, AlwaysWrong. It's amazing that anyone can be
so consistently wrong.
Jeff Liebermann <jeffl@cruzio.com>: Jul 06 08:18PM -0700

On Wed, 06 Jul 2016 08:12:36 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
 
>I looked inside with a magnifier, yet had an accumulation of lint at
>the bottom of the connector which was preventing the connector from
>seating properly.
 
Here's a YouTube video showing the pocket lint in the connector
problem and cleaning procedure:
<https://www.youtube.com/watch?v=R6p0Eg-yq3A>
 
--
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
DaveC <not@home.cow>: Jul 06 09:40PM -0700

On 6 Jul 2016, Jeff Liebermann writ:
 
> Here's a YouTube video showing the pocket lint in the connector
> problem and cleaning procedure:
> <https://www.youtube.com/watch?v=R6p0Eg-yq3A>
 
Appreciate the pointer Jeff; that's the first thing I did. Didn't change
the symptom I've reported here.
 
Cheers.
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