How to repair fine traces?

[Kabeern]

Hi,
I need some help kinda quick.
Basically how to apply liquid ink (or something better?) in a very fine and thin manner?

I have a ortho/magnaplanar/isodynamic, whatever you wanna call it driver (specifically one from a Yamaha headphone).

There is a break in the diaphragms coil.
Here is a photo of the type of diaphragm im reffering to:
Diaphragm photo

The whole diaphragm diameter is about 50mm, to give you a rough idea of size.

Current plan to repair the broken trace is to use liquid conductive ink from a conductive pen. But the problem remains on how to apply it very finely so it doesnt affect the diaphragm too much, and to minimise it touching the other traces (although touching a few traces isnt going to kill it).
Basically all we can think of so far is using a finger to dab a little ink on....

Help is greatly appreciated, thanks!!!

[arend-jan]

The picture that you link, although interesting it may be, isn't working. Try to attach it to your post intead.

[SY]

Conductive ink may need to be thinned slightly with MEK- it tends to blob up. I'd use the tip of a pin to pick some up and touch it to the right spot. Magnifying glasses and a means to brace your wrist (a Mahl stick could work) would be very helpful. Be relaxed, don't drink coffee beforehand.

[dBel84]

Sy , I have wondered about solvents to thin out the conductive ink. Do you think the MEK is safe to use on a 12micron polyester membrane? TIA ..dB

[arend-jan]

Methyl Ethyl Ketone is not good for your PET film. Even short (1 minute) exposure will result in decreased yield stress and stress at break. That being said, for this application I doubt it would have serious consequences.

[dBel84]

this was my concern, even at short / small exposures..dB

[Kabeern]

Originally posted by arend-jan
The picture that you link, although interesting it may be, isn't working. Try to attach it to your post intead.

Sorry about that. I uploaded it to my flickr account now ~(click to enlarge):

Originally posted by SY
Conductive ink may need to be thinned slightly with MEK- it tends to blob up. I'd use the tip of a pin to pick some up and touch it to the right spot. Magnifying glasses and a means to brace your wrist (a Mahl stick could work) would be very helpful. Be relaxed, don't drink coffee beforehand.

Thanks! Actually, dBel84, who posted below you will be carrying out the repair. So let's see if he thinks its possible to do...

[bear]

They make a copper liquid for repairing the heater/defroster on the back of car windows. That withstands heat well and conducts.

Try that. Auto parts store. Look for the copper containing one.

_-_-bear

I'd also consider painting the surrounding area with a thin lacquer or other thin insulating coating before applying the conductive paint - a mask effect. You might be able to use something that has an easy solvent removal like a wax... when I say paint, I don't mean very much,just enough to insure that you don't short a turn.

[dBel84]

These headphones work on a planar principle and as such the sound is intricately connected to the speed of the diaphragm. One of my biggest cautions with trying to repair this driver is not to change the density/weight unevenly on the single surface and more importantly, relative to the second driver - any imbalance is easily perceived in headphones and would negate the initial effort.

I speak from a little experience here as I have unfortunately had to repair a similar driver for another friend and the repaired driver works well but the channel imbalance is frustrating and measures to correct this imbalance have resulted in an inferior sound ( it is still superb but not as good as it was and this knowledge gnaws away while using them)

thanks for all the input, the collective process may yet yield a simple solution..dB

[SY]

Originally posted by arend-jan
Methyl Ethyl Ketone is not good for your PET film. Even short (1 minute) exposure will result in decreased yield stress and stress at break. That being said, for this application I doubt it would have serious consequences.

There's only a brief exposure in a small area. It's unlikely to have a bad consequence. The nice think about thinning with MEK is that the added mass will small and the drying time will be very quick. Ethyl acetate would also probably work as a thinner but is a "slower" solvent.