Finding a break in a wire

[Nelson]

I have a number of relatively expensive headphones that have stopped
working. There are apparently breaks in the wires caused by fatigue.
Since the connections at the ends are molded, it's hard to simply
replace the wire. Ideally, I'd like to find the break, open the
insulation at that point and patch the break. Unfortunately, I can't
think of any way short of a time domain reflectometer to pinpoint the
break.

I realize that in extremis I can cut the wire at both ends close to the
molded edges and patch in a new wire, but I am looking for something
less drastic. Has anyone discovered any good techniques for such
situations?

--
Nelson

 

[N_Cook]

Nelson <nelson@nowhere.com> wrote in message
news:0001HW.C52AFA8A01A0A35AF0488648@news.astraweb.com...

I have a number of relatively expensive headphones that have stopped
working. There are apparently breaks in the wires caused by fatigue.
Since the connections at the ends are molded, it's hard to simply
replace the wire. Ideally, I'd like to find the break, open the
insulation at that point and patch the break. Unfortunately, I can't
think of any way short of a time domain reflectometer to pinpoint the
break.

I realize that in extremis I can cut the wire at both ends close to the
molded edges and patch in a new wire, but I am looking for something
less drastic. Has anyone discovered any good techniques for such
situations?

--
Nelson

Give this tip a go but if you do please report back, whether successful or
not.
I suspect it won't work because of the close proximity of adjascent wires.

Searching for a buried wire or even trace tracing in a
multi-layer board.
Where you can only connect a signal to one end.
Make a sniffer from the pole pieces and coil of a
high ohmic relay.
I used a shallow flat pack (small diameter solenoid) 48V
relay as you used to find on
telecom boards, this one an NEC MR48S 24, 4200 ohms,
fixed to an empty ballpoint pen barrel.
Connect to an op-amp with high gain and feed into
a crystal earpiece. Connect an audio sig gen set to
about 1KHz, square wave and high amplitude
and sniff with the pole piece/s in
translating and rotation to zero in on maximum tone,
position and direction of the conductor.
For more discrimination connect a DVM on AC range
in place of earpiece and set sig gen at about 8KHz
for highest response.
For single connection, ie not current through the
conductor then detection distance with earpiece
only about 10mm but about 50mm for 8KHz and DVM.

other tips off URL below

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Dave Plowman (News)]

In article <0001HW.C52AFA8A01A0A35AF0488648@news.astraweb.com>,
Nelson <nelson@nowhere.com> wrote:

I have a number of relatively expensive headphones that have stopped
working. There are apparently breaks in the wires caused by fatigue.
Since the connections at the ends are molded, it's hard to simply
replace the wire. Ideally, I'd like to find the break, open the
insulation at that point and patch the break. Unfortunately, I can't
think of any way short of a time domain reflectometer to pinpoint the
break.

I realize that in extremis I can cut the wire at both ends close to the
molded edges and patch in a new wire, but I am looking for something
less drastic. Has anyone discovered any good techniques for such
situations?

In 99% of cases it will break where there is the most movement or strain -
which is usually just up from the plug.

I bought quite a nice little signal tracer kit off Ebay - it sends an RF
signal up the wire and uses a separate receiver to trace it. Works well
where I've tried it - but not used it for mm accuracy.

--
*Time is the best teacher; unfortunately it kills all its students.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[William Sommerwerck]

In 99% of cases it will break where there is the most movement
or strain -- which is usually just up from the plug.

Over the years I've noticed that "strain reliefs" often cause the exact
problem they're supposed to prevent. The strain relief is too short and too
stiff.

 

[Eeyore]

Nelson wrote:

I have a number of relatively expensive headphones that have stopped
working. There are apparently breaks in the wires caused by fatigue.
Since the connections at the ends are molded, it's hard to simply
replace the wire. Ideally, I'd like to find the break, open the
insulation at that point and patch the break. Unfortunately, I can't
think of any way short of a time domain reflectometer to pinpoint the
break.

Forget it.

When it's got to that state it just breaks again somewhere else inside a
month.

Graham

 

[Dave Plowman (News)]

In article <ge47d8$23k$1@registered.motzarella.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

In 99% of cases it will break where there is the most movement
or strain -- which is usually just up from the plug.

Over the years I've noticed that "strain reliefs" often cause the exact
problem they're supposed to prevent. The strain relief is too short and
too stiff.

I repair quite a few personal mics as used with radio mics, and they
invariably go close to the connector. Where the cable clamp is. Extending
the support just means the cable fails slightly further up. ;-) Since on
many it's pretty difficult if not impossible to replace the cable I now
prefer to have it break as close to the connector as possible. This gives
the maximum number of repairs before the cable becomes too short.

--
*Being healthy is merely the slowest possible rate at which one can die.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.