speaker repair
R Oxley
The speaker was not working at all, the voice coil wires were broken away
from the solder pads, the plastic spider was warped/twisted, and the magnet
was falling out. I've got everything fixed, except that I cannot remove the
varnish from the extemely fine voice coil wires. They are like 60 gauge,
fine as hair, too thin to scrape, too thin to use even the finest grit
sandpaper, and I've tried both denatured alcohol, and acetone trying to
disolve it, and heat from the soldering pencil, but nothing will strip the
insulating varnish to allow me to solder the wires. I've already had to
unwind the coil slightly to get enough slack to bring the leads to the edge
of the cone, and don't want to have to do it much more. I've been luck so
far, but I'm sure that much more pulling for slack, and it will break too
close to the coil.
So, any suggestions on how to remove a few millimeters of varnish to expose
the copper? Working with this very fine gauge of wire is frustrating!
Bob
Peter Wieck
>So, any suggestions on how to remove a few millimeters of varnish to expose
>the copper?
I have had some success using a hot (40-watt) iron, constantly renewing the
solder on the end. Eventually, the flux will erode the varnish. Takes several
inches of solder to get there, but be patient.
Failing that, strong white vinegar on the blackened end will sometimes cause
the blackened varnish to come off.
http://members.aol.com/pfjw/page1.html
Peter Wieck
Al-Khobar, KSA
Henry Kolesnik
older stereo headphones have small speakers in them and the
surplus houses sell them. If you can't get it fixed you might find one. --
73
Hank WD5JFR
"R Oxley" <tychou...@SPAMyahoo.com> wrote in message
news:w1Lyd.1581$yW5.1565@fed1read02...
Ken G.
truegridtz
lacquer thinner, naptha, toluene. Sometimes none of these will strip some
types of coatings.
If you have any carburetor spray put some on a q-tip. Brake rotor cleaner
may do it. Carb spray usually has four or more of these solvents in it and
it may do the trick if you give it time to soften it. Mark
"R Oxley" <tychou...@SPAMyahoo.com> wrote in message
news:w1Lyd.1581$yW5.1565@fed1read02...
Bill J
years for this kind of thing.
R Oxley
"Henry Kolesnik" <kole...@sbcglobal.net> wrote in message
news:GkXyd.8297$wi2....@newssvr11.news.prodigy.com...
> My hat's off to you for the patience to attempt such a repair. Some of
> the older stereo headphones have small speakers in them and the
> surplus houses sell them. If you can't get it fixed you might find
>
> 73
> Hank WD5JFR
Thanks for the idea, Hank. I've got a bunch of old headphones laying around.
Being the packrat I am, I could not bring myself to toss them, at least
without prying loose the nice strong magnets they usually contain. I have a
slightly larger than average skull, so I wear the largest size hats, and
tend to overstress the headband part of the smaller headphones, causing them
to crack over time, so I've got a bunch of old unwearable pairs here and
there.
I think those stereo phones tend to be about 16 ohms impedence, and the
speaker I need to replace is 8 ohms, but that might not be a problem. The
device I am repairing is a microprocessor controlled radiation monitor, an
Eberline model ESP-2. I have an ESP-1, which is superficially similar, and
it's speaker is much too loud. I suspect it was made that way so that
nuclear workers wearing a full isolation suit could still hear the clicks,
or the alarm tone, even while their heads were covered by the hood of the
suit, or in a noisy environment. But as I don't plan to be using it like
that, a lower audio volume level would be welcome. I've been planning to
install a small volume pot in the other counter.
As the duty cycle of the audio portion of this device is rather low, I don't
think the impedence mismatch will have much effect, except for the lower
volume level. And the audio fidelity is a non-issue. It only puts out
"geiger counter" clicks, and a 1000 Hz alarm tone. It doesn't have to sound
good.
How I got started with collecting radiation detectors is a long story.
Suffice it to say, that I got my start thinking about the possible future
threat of terrorist created radiological (dirty) bombs, plus the fact that I
work on a Navy base with upwards of 3 or 4 nuclear aircraft carriers moored
alongside from time to time, and decided I wanted a personal ability to
detect and measure such things, not trusting to government to be
immeadiately and totally forthcoming with such news. I acquired a small
geiger counter, and a low range pocket dosimeter, and some low output, legal
test sources. Then my addiction to electronics got hold of me, and I started
buying and fixing older, broken geiger and scintillation detectors on Ebay.
Now I have a collection of them to go with my growing collection of old
vacuum tube radios, and antique pocket and wrist watches!
Bob
R Oxley
"Ken G." <good...@webtv.net> wrote in message
news:20462-41C...@storefull-3251.bay.webtv.net...
> Old radar detectors have tiny speakers
>
I've got one of those laying around also. One of those from Radio Shack that
had the voice announcement system. I've suspected for a while now, that it
was not working quite right, so it's been out of the car for a while now.
Thanks!
Bob
Engineer
>
Also small memo-type recorders.
Cheers,
Roger
Jim Adney
<tychou...@SPAMyahoo.com> wrote:
>So, any suggestions on how to remove a few millimeters of varnish to expose
>the copper? Working with this very fine gauge of wire is frustrating!
Heat the tip of the wire very gently with a match. That will burn off
the varnish and leave an easy to remove ash. I've never done it with
wire this small, so it might get too hot too fast and melt. I would
just watch for a little puff of smoke indicating that the varnish has
burned and then quit.
I usually follow up with a small piece of 600 grit paper folded gritty
side together so that you can gently squeeze down on the wire while
you draw it thru. This polishes off the ash and oxidation.
I've done this with wire up to about 40 AWG with no problems. I've
never seen the wire melt, but it will glow bright red. This works well
because it subjects the wire to minimal stress.
Some varnishes are made to melt back at soldering temps and some
aren't. That's an easy thing to try first, but if it doesn't work on
wire this small in a minute, then it won't work in an hour.
-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
R Oxley
that worked. Turned out that I had one with a broken headstrap. I took it
apart, and it was an exact fit into the circular depression it had to fit
into, and it is in place, and working very well indeed. Just out of
stubborness, I'm still going to get the original speaker working, after this
much effort. But now, there is no pressure to get it working!
I'll try the flame treatment. Makes sense, as the varnish should become a
fuel and burn off, whereas it might not when submerged in solder. Being
exposed in open flame would tend to accelerate the oxidation process. I'll
let you know.
Thanks for all the suggestions, especially the salvage/recycling ideas.
Bob
david bondzio
- Dip the swab into the ammonia, squeeze the tip to remove excess then go once around the v/c wire making sure to get good coverage.
- Now wait a minute.
- Repeat the dip and squeeze process then gently go aruound the v/c again.
- Take a look at the swab to see if any color is on it. If there is color and the color matches what's on the v/c, the coating is most likely varnish.
- Repeat the process of going around the v/c until you are getting *close to the desired result. What I mean by that is the cleaning process will be completed by swabbing with distilled water to neutralized the ammonia. *More of the varnish will be removed as you swab with the water.
- This is a trial and error technique - so take your time and proceed with the utmost caution
Paul P
too. BE QUICK. VERY Quick!!! Or you will melt the wire.. :~)