[TiredHornet]

Hi,
 
I just joined this forum because there seems to be a lot of knowledge on DIY for headphones here and I might have broken one of the drivers on my Koss PortaPro. Here is what I did:
 
I attempted to repair the plug on a PortaPro. I bought a decent plug from Neutrik and replaced the old plug. I had some issues with the solder since it was without flux but eventually the solder stuck to the connector. However, testing the headphone I noticed the sound was weaker on the left side. So I rechecked the solder points at the plug but all seemed fine. Playing around with the cable I noticed that the sound would disappear if I pulled or pushed the cable at the earphone end. So, I took the driver a part to have a look. The cabel looked fine but now I get no sound at all.
 
What I have tried so far:
 
1) I removed and resoldered the cable.
2) I tried a different cable from a pair of cheap ear plugs.
3) I held the PortaPro cabel with the new plug to contact on the little driver of the ear plug and I could hear sound.
 
After all these test I would conclude, that I somehow damaged the driver. Maybe the heat from soldering the plug was transfered along the wire to the driver and fried it? Does anyone have an idea what else I could try?
 
Best regards,
TiredHornet

 

[HiGHFLYiN9]

You can damage a driver with heat if the heat is applied for too long, but to have the heat travel along the 4 foot cable and damage the driver seems a little out of the ordinary unless you were heating the solder joint for a really long time. I assume you have a multimeter, can you measure the resistance between the plug and the driver pad? 

 

[tangent]

1.  

HiGHFLYiN9, you missed the part where he admitted to taking the driver apart.
 
TiredHornet, you made several newbie mistakes:
 
1. Headphone cable is usually lacquer-coated. Until you burn off the lacquer, the solder won't stick.
 
2. Headphone cable is delicate -- ~30 ga -- so it's easy to break. You probably weakened the wires near the joints inside the new connector, which explains the problem when wiggling the cable.
 
3. Tearing apart the driver and replacing the whole cable is not a good first project. It's better to replace several connectors first. That will teach you how to handle lacquered 30 ga wire. Once you've mastered that skill, you can start doing it at the driver end, which is easy to damage, as you've found.

 

[TiredHornet]

Thanks for all your input:
 
Quote:

 You can damage a driver with heat if the heat is applied for too long, but to have the heat travel along the 4 foot cable and damage the driver seems a little out of the ordinary unless you were heating the solder joint for a really long time. I assume you have a multimeter, can you measure the resistance between the plug and the driver pad? 

 
I don't have a multimeter. But, the cable and the new plug should be fine, since I have already tested them with a driver from another headset and the sound came through (third point in the OP). But, I'll see if I can get a multimeter and measure the resistance. Is the "driver pad" the place where the cables where soldered to the driver?
 

  HiGHFLYiN9, you missed the part where he admitted to taking the driver apart.
 
TiredHornet, you made several newbie mistakes:
 
1. Headphone cable is usually lacquer-coated. Until you burn off the lacquer, the solder won't stick.
 
2. Headphone cable is delicate -- ~30 ga -- so it's easy to break. You probably weakened the wires near the joints inside the new connector, which explains the problem when wiggling the cable.
 
3. Tearing apart the driver and replacing the whole cable is not a good first project. It's better to replace several connectors first. That will teach you how to handle lacquered 30 ga wire. Once you've mastered that skill, you can start doing it at the driver end, which is easy to damage, as you've found.

Let me address your points:
 
1) I did remove the lacquer-coating from the cable. The solder wouldn't stick to the plug. I was told this has to do with me having solder without flux. --> Need to get some flux for next time.
 
2) This is of course possible, but since I used the same wire and plug successfully with another driver, it seems unlikely. I didn't touch the driver until the sound was completely gone. So unless, the heat travelled down the 4 foot cable from the plug, I don't know how I could have damaged it.
 
3) I agree that it would not be a good first project. But, I didn't see any alternative...
 
Since I tried a cable know to be working with another driver, should I assume the driver is toast? The solder points on the driver look kind of dirty. The solder is a bit grayish with some brown dots. Could this be an issue? Should I maybe try to remove the solder from the contacts on the driver using a pump and then resolder the cables with new solder (and flux)?
 
Thanky again for all your suggestions and comments. If you have any more keep them coming...

 

[awehns]

Send it back to Koss and they will probably replace it, no questions asked.

 

[tangent]

  Is the "driver pad" the place where the cables where soldered to the driver?

 
Yes. "Pad" is short for "solder pad", which means an exposed bit of metal intended to be soldered to.
 

The solder wouldn't stick to the plug. I was told this has to do with me having solder without flux. 

 
If the solder smokes when you touch your iron to it, it has flux. Solder without flux is very much the exception.
 
Some people find it helpful to add liquid or paste flux to a joint. I have found it helpful myself, but on cables, it's typically only because I've spent too long on the joint so all the flux has been burnt off.
 
More typically, problems with getting solder to stick to a connector comes down to not being able to get enough heat into the solder lug quickly enough. This is not to say that you need a hotter iron, but that you need one that has less sag in its heat output when you touch it to a big lump of metal. A hotter iron can have the same net effect, but you have to be careful to avoid overheating things. With 1/8" connectors, the risk is melting the plastic insulation that keep the 3 separate connections separate.
 

So unless, the heat travelled down the 4 foot cable from the plug, I don't know how I could have damaged it. 

 
HiGHFLYiN9 is right: you didn't overheat the driver through the cable. 
 
However, there are many other ways to kill headphones.
 
With headphone cable, I'd guess the main causes have to do with not understanding how stranded wire behaves under physical stresses.
 
When you solder to stranded wire, it wicks the solder away from the actual joint, bonding the strands together for some distance past the obvious part of the joint. This makes that section of wire brittle. You must apply strain relief after that point, else you can break the wire with tugs that the stranded wire would tolerate.
 
But just as bonding all of the wires together makes them more brittle, so does not keeping them close enough together. If you fray the wire a bit near the joint, it allows you to break the wires individually. This is the same principle behind the "rip a phone book in half" trick.
 

 I didn't see any alternative... 

 
I gave you one already: make a project of replacing several 1/8" plugs before graduating to work on the driver end of the cable.
 

should I assume the driver is toast? 

 
No, you should measure it and find out.
 

The solder is a bit grayish with some brown dots. 

 
Grayish means you probably burned off all the flux while making the joint, which makes it turn pasty, which makes for a bad joint.
 
The brown dots are burned flux. They're not a problem in themselves, just a symptom. If the joint were shiny, you'd have every reason not to worry about the burned flux, except insofar as you should clean it off afterward. Burned flux is somewhat conductive -- you've carbonized it, and carbon is a conductor -- and flaky, so it could fall off and short something out.