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Koss PortaPro Driver testing

post #1 of 8
Thread Starter 

Hello all!

I'm running across a problem unfamiliar to me until now. I've had the PortaPro's since 2010, and have had no problem so far. I've changed the plug and rewired them multiple times with success, and had no isues until today.

This morning, one of the drivers stopped working. After opening them up and checking, the most obvious thing showed up (a dissoldered cable).

Once again, I soldered all of them back in their position (since I was doing it for one driver, and in order to avoid a different cable lenght, I decided to recable both). I tested there was continuity between tip, body and ground from the plug to their respective drivers/lead.

 

However, there was one little thing that posed strange to me. Everytime I resoldered the drivers before, there was a faint continuity between the 2 leads in the driver itself (between those 2 leads which are supossed to be soldered to either tip/body and ground).

This time, there was no continuity. When I got everything back together, no sound came from the speakers. I retested the continuity between the leads (flawless), and that faint continuity between the 2 leads was still absent.

 

Unfortunately, I can't get the PortaPros to come back alive again, and I wish for you guys to help me a little with this.

Actually, it would be great if any could provide some tips for testing the drivers, or even better, a schematic of how should the leads be related to each other in the driver. As far as I know, a little speaker (as the driver is) should only have voltage and a reference, there shouldn't be any other "special" structure inside. That's why I'm still confused about what could have gone wrong, or what exactly is going on with my drivers.

 

Any help would be appreciated.

 

Thanks in advance!

post #2 of 8

What do the following things measure:

Tip to sleeve?

Ring to sleeve? 

Tip to ring? 

 

If they are not 60, 60, and 120 ohms try resoldering them. 

 

If you resolder them, and everything is soldered where it is supposed to be soldered, your drivers are probably busted. It happens. Smash them up with a hammer and buy new ones. Save the headband - KSC75 on a portapro headband is a cool mod. 

post #3 of 8
Thread Starter 
Quote:
Originally Posted by nikongod View Post
 

What do the following things measure:

Tip to sleeve?

Ring to sleeve? 

Tip to ring? 

 

If they are not 60, 60, and 120 ohms try resoldering them. 

 

If you resolder them, and everything is soldered where it is supposed to be soldered, your drivers are probably busted. It happens. Smash them up with a hammer and buy new ones. Save the headband - KSC75 on a portapro headband is a cool mod. 

 

Thanks for the response!
I just tested what you asked:

They all measure 0 ohms, no continuity. I'll resolder them meanwhile.

BTW, the cable I'm resoldering them into isn't the stock one. Over the days, the original cable was destroyed (mostly by skin oil hardening) so I'm using a different one (the headphones were working fine on this cable).

post #4 of 8
Quote:
Originally Posted by Persheis View Post

 

They all measure 0 ohms, no continuity. I'll resolder them meanwhile.

 

 

0 ohms is pure continuity = shorted.

If they measure 0ohms (same as what you get when you hold the tips of the meter-probes together) I would check that there are no shorts in the plug. It is also possible that there is a solder bridge or a loose strand of wire in the headphones. 

 

If they measure (zero) (space) (space) (decimal point) (space) {exact sequence of spaces and decimal marker depends on your meter} like when the probes are touching nothing, the connections are open. This usually means busted drivers. 


Edited by nikongod - 2/17/14 at 8:37am
post #5 of 8
Thread Starter 
Quote:
Originally Posted by nikongod View Post
 

 

0 ohms is pure continuity = shorted.

If they measure 0ohms (same as what you get when you hold the tips of the meter-probes together) I would check that there are no shorts in the plug. It is also possible that there is a solder bridge or a loose strand of wire in the headphones. 

 

If they measure (zero) (space) (space) (decimal point) (space) {exact sequence of spaces and decimal marker depends on your meter} like when the probes are touching nothing, the connections are open. This usually means busted drivers. 


Unfortunately, I think it may have to do with the drivers. When I measure them, I get the same response as if I were measuring nothing.

I think it might have to do with the coil wires being broken (as I recently noticed the slimmy and sticky substance that runs from the bottom is cut out), and, obviously, they solder pads don't reach the drivers at all.

I guess there's no remedy, but oh well, they served their purpouse for a long time. xD

 

Going a little back on the subject, you metioned KSC75 drivers would fit in the headband. Do they fit right away? Or do I have to do tamper them a little for them to fit in?

Also, would the KSC75 drivers do? Or  should I also give the Sportapros a shot?

 

Thanks for your help so far. :D

post #6 of 8

Sorry for the delay. 

 

KSC75 drivers fit in the Portapro frame just fine. 

 

No idea about the Sportapro. 

post #7 of 8

Hey! First post!

 

I've have both the SportaPros and the KSC75's and can confirm they have identical clips.  You can use the KSC drivers on the SportaPro (what a stupid name?) headband, and the SportaPro drivers on the KSC clips.  They attach in the same way so no alteration required.  From all I've read they will both fit the PortaPro headband as well.

post #8 of 8

...And I believe the SportaPro has the exact same drivers as the PortaPro, where as the KSC75's have the "titanium-coated" version.  Highs have a little more sparkle on the titanium drivers, but the difference to my ears is subtle.  Some people prefer one, some people prefer the other.

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