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Headset repair fault

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IPDO

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Hi,
Once I found that my microphone is not working, I opened the headset and saw the mic wire came off the solder. Then i soldered back on its correct position but unfortunately a mistake has occurred during this process. The small card came out as shown in fig. I have taken a picture of right speaker to show how the left speaker would look like before.

And Thanks for any Help in Advance.
 

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Hi"

Click the second pic at the bottom of this https://www.crutchfield.com/S-QKbzjg0B4OH/p_068R48N/Retrosound-R-48N.html page. It should show the back of a speaker.

What you have there is a "card" with two terminals on it. This particular one has 2 sets because it's a dual voice coil. This "card" should be mechanically fastened to the speaker.

Those terminals provide a transition from the outside world, then some very flexible wire and then the speaker's voice coil. The flex wire/voice coil connection is seen on the front of the speaker under some insulating material.

Your pics are a bit blurry.
 
There should be two very flexible wires attached to the speaker and also attached to the terminals of the "card". These could be broken which is what I expect. Look at the other one.

Then the headset wires attach to the card.

Your speaker should work with the "card" hanging.

If it does, you can glue it back in place.

Much better pic.
 
I can't see any wires either, but they have to be there or they got pulled out. You MIGHT see remnants on the "card". The drop of glue, may have secured them on the speaker side and they could look like a splinter in your hand. A tiny dot.

I can't find a really good pic, but post #9 here https://www.head-fi.org/t/615687/should-i-restore-these-speakers-help-advice-wanted shows a typical speaker construction.

You have a "powdered magnet". The "voice coil" is attached to the cone and moves between two magnets. One a cylinder and one a donut.

On a conventional speaker, these wires are varnished close to the center of the cone and emerge on the backside of the cone as lintz (very flexible wire). The "dust cap" in the center of the speaker covers the voice coil.

Those fine wires are taken to a fixed point on the speaker. The "card" in your case.

There is usually no slack in these wires as it would be perceived as a rattle. They just have to move the amount the cone moves without scraping anything. They are usually insulated with a varnish.
 
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I'll bet the yellow/white glue is hot melt glue and the clear is polyurethane. To affix your "card", I's probably use contact cement.

Those "copper" wires are insulated with a very hard to strip varnish insulation. Scraping risks cutting the wire and the chemical stripper for Formvar is very hard to come by.

This https://forum.allaboutcircuits.com/showthread.php?t=29861 probably sums it up.

The suff is called "magnet wire". e.g, **broken link removed**. You might be able to salvage some from an old small transformer.

Repair will be EXTREMELY tricky.
1. Expose the ends without damage,
2. Strip without damage.
3. Solder or conductive epoxy together.
4. Insulate.
Anything is going to be messy, High voltage corona dope might work.
Nail polish.
Kapton tape might provide an insulating layer. Resists 200C and easily removable and about 0.001" thick.
Locktite wire tach might help too. It's a sort of glue to place wires on a PCB so they don;t move.

Your in India and I have no idea what's available to you.

All I can say, it will be difficult, if not impossible. Practice on new wire would be a good thing.

It's gonna be really hard.
 
the insulation can be removed mechanically or chemically. Fine wires make breaking the wires extremely easy. I've used a Dremel tool on very thick wires and also sandpaper. e.g 320 grit. And even a Razor blade.

Without practice, you will easily risk breaking the wire.

Concentrated Formic acid > 85% supposedly will also work. The problem is you would have to buy way too much, but sometimes it's the only way.

I remember a time where I purchased a specialized window cleaner with trace amounts of Hydrochloric and Hydrofluoric acids. I've used concentrated Hydrochloric and Hydrofluoric acid (HF) at work and the dangers are really nasty. HF is very easily absorbed through the skin and it etches glass. Later my work required certification to work with it, But, the window cleaner worked wonders and saved a lot of $ for window replacement. I had to buy a gallon, about 2.x liters. The training videos for HF are scary.

Disposal would be easy. Just neutralize with baking soda (Sodium bicarbonate) and down the drain.

Currently, I use it to clean a glass container that I keep iced tea in.

Chemicals don't bother me as log as you use the right personal protective equipment. Pesticides and Herbicides can be quite nasty too.

There is a "slight chance" that the wire is not Formvar insulated and paint remover will work. I also buy a small amount of methanol to have at home. The primary use is to remove permanent ink stains and it won't damage plastic.
 
Another way to remove the enamel from fine magnet wire is to burn it off with a match flame (if you have room), then very fine abrasive paper used carefully can remove the residue more easily.
 
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