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Vintage SR-125 pinks needs rescue

post #1 of 9
Thread Starter 

I recently found a pair of SR-125s with pink drivers. I just couldn't help myself even if one side was out and the pictures were out of focus and of low quality. I could still see what seemed to be a pristine pair of 13-14 years old Grados, and boy if they were! 15 minutes after getting home from the post office, I had them open, but sadly I got no response when ohming the dead driver D: So, this is where I turn to you, the more experienced Grado lovers. From what I can see, both voice coils seem to show through the black wax-like putty covering the ends of the solder tabs. It's a bad solder job, but from looking at it I absolutely don't get the impression that the previous owner has opened and tried to fix these. The phones are so pristine that I think they must have broken pretty early on, and stayed in a drawer for most of it's life. These are definitely different from my old Grados anno 2006. The headband, while being made of some rubber-like material, are way softer than the new headbands. The lettering on the cups also seem more substantial, and have a less shiny chrome appearance. Maybe more in the likes of lightly polished tin.

 

PS. Can the voice coil itself have broken inside of the driver? Maybe the old drivers were of a lesser quality? Again I turn to the more seasoned head-fiers for their experience.

Also, maybe some out there are good at repairing voice coils? I'm guessing that Grado themselves don't supply or repair the pink drivers anymore.

 

 

 

 

post #2 of 9

What does it say when you measure the resistance at the driver pads? 

 

Once you verify that the cable is broken, and the drivers are fine, be careful while you are taking the old cable out. A few people have torn that little PCB off while taking the cables out. 

post #3 of 9
Thread Starter 
Quote:
Originally Posted by nikongod View Post
 

What does it say when you measure the resistance at the driver pads? 

 

Once you verify that the cable is broken, and the drivers are fine, be careful while you are taking the old cable out. A few people have torn that little PCB off while taking the cables out. 

 

"There was no response" so 0 ohms against the usual ~32 ohms :)

 

Yeah I didn't bother ohming the cables, but I did now just for the sake of it, and got full connection.

 

No worries, I know my way around with a soldering iron ^_^ I'm guessing people boil off the glue at the back side of the PCB while de-soldering?

 

EDIT: I could liberate the driver if you wanted pictures of the voice coil routing canal. I'm not sure if it would make much of a difference tho, as I suspect the problem is either inside or at the soldering tabs.


Edited by Corleone - 1/31/14 at 1:51pm
post #4 of 9

Its just really unusual for the driver to break before the cable. Sometimes it can be difficult to measure impedance at the driver due to a layer of funk over the connection. 

 

Yes, as you said, people occasionally melt the glue while soldering and then poof. Some have also just ripped the boards out.

 

I would unsolder the cable, solder a new cable on (or just solder on a couple short wires to a plug) and try it off of a walkman or something. 

 

Don't take them apart any further than you already have. The deeper you go the more likely you are to destroy them yourself. 

post #5 of 9
Thread Starter 

The drivers were unresponsive while playing them, which was the first thing I did. I also cleaned the soldering points before de-soldering the cable. The funk you're talking about is flux residue, but I have never seen a soldered point covered completely with flux. This is due to the properties of the materials used for such purposes - it flows outwards when heated. I also ohmed everything, including the same soldering points (before and after) to make sure that I was getting reads. There's definitely something with connecting the voice coil, or a short in the coil itself. I'm badly hoping for the first one, and for a knight in shining armor to ride into frame ;D

post #6 of 9

Did you measure the original cable after you removed it? 

 

Don't be afraid to test a few more things to verify that it is really the driver that is broken. 

 

Once you have exhausted all possible things *other* than the driver the best way to fix a damaged headphone driver is to put it on a hard, flat surface (ideally an anvil, but a asphalt or concrete slab is equally suitable) and whack it with a mallet. 

Then you spend your time on something productive. 

 

Here is what the inside of an SR-125 driver looks like. 

DBP

 

The voicecoil is behind the "cone." The cone is glued to the frame. Good luck getting it apart without total destruction. Save yourself an hour of frustration and smash it with a hammer. 

If you are careful you can actually pry the magnets out of the backs of the drivers and maybe use them for something else. I have a pair of RS-1 magnets I use to hold stuff to my refrigerator. 

post #7 of 9
Thread Starter 

x'D This made my day! Sadly I know all this and have even been inside a couple of drivers. I'm talking about finding some adept that is good at removing the black putty (white on new drivers) and re-soldering the voice coil to the tabs without messing anything up. I do wonder if it's really possible, as the putty seems to melt around anything when soldering, effectively coating anything disconnected.

 

PS. Yes I measured it after de-soldering too.

post #8 of 9

Don't know about the 125s, but if the driver 'cups' are built like my 325s, good luck getting the driver out of there! You're probably better off trying to email Grado to get a replacement. I was lucky enough when my sr325is broke down that only the cable was dead, the drivers were at ~32ohms each.

 

If that's not an option and you really want to try this, you MIGHT be able to melt the putty using a hair blowdryer. Food for thought.

post #9 of 9
Thread Starter 

Yeah I was actually contemplating that! I'm a bit scared of warming the membranes too much tho. Might be worth a shot, but I'll give it some more thought first.

 

Regarding liberating the drivers: it's not really a problem. I've liberated a few sets as many have done before me. All models from SR-325 and below have the same inner cup design with the drivers CA'ed to the inner cup sleeves. :)

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