Guidance needed on how repair broken membrane traces on Apple Design Keyboard

[TimHD]

Hi

I am trying to see if it's possible to repair broken traces on the membrane that sits inside an Apple Design Keyboard (M2980) below the rubber domes under each key.

I have 2 of these KBs - 1 almost platinum and another yellowed with age. One works perfectly, one has a number of keys not working. And as you'd guess the good looking one has the issues, the ugly one works fine!

I was just going to swap the insides around to have one "good" KB but it turns out the internals of these are different despite being the same model no (and no mention I could see of different revisions on the net!).

From comparing the keys that aren't working (e.g. characters and symbols up in the top right of the text part of the keyboard and the keys 789 and above/to the right, in the number pad) and looking at where these key's rubber domes strike the membrane and following the traces, it seems that there's a rusting / break in the traces near the connecter to the controller.

See image

https://68kmla.org/forums/index.php?/gallery/image/846-apple-design-keyboard-membrane-damage/

Given this is plastic membrane, I need a solution that doesn't involve soldering irons, to repair these traces. Any McGuyver solutions out there?

 

[CC_333]

Maybe one of those conductive ink pens that are used to repair resistive rear-window defrosters in cars could work?

c

 

[Elfen]

Your links gives a permission error.

But other than that, CC_333 hits it spot on - conductive ink pen. The one made for a car's defrost mesh uses cooper. There are other brands; Radio Shacked used to sell this one, it uses nickel: http://www.mcmelectronics.com/product/20-4930

These conductive ink pens uses lacquer, so use in a well ventilated area.

 

[zerobotman]

I ocasionally repair broken traces on boards. usually my method is to connect the things disconnected by broken traces with hookup wire such as if a pin from an ic has a broken trace between it and something I'll just run a wire to that other thing. this usually works but can get messy especially when you need to connect things between the top and bottom of the board. if it's a big trace and a small break (such as a wayward knife scratching through a trace) you can sometimes get away with spacing away some epoxy off the traces and dropping a solder blob between them.

 

[Elfen]

A Perfect solution for logic boards, ZeroBotMan! But this is a membrane film some keyboards use. Putting heat to it will melt it. I destroyed one on a Duo 230 by taking it apart and wiping it down with Acetone to clean it - stripping away a good chunk of the keyboard matrix painted wiring right off the membrane film!

 

[zerobotman]

Oh he's talking about the clear plastic film that the keys make contact with. Ya that's a tough fix. This may also be a long shot but if you find out which company manufactured it, if it was contracted out, then you may be able to find more available keyboards that use the same membrane. other then that i guess the conductive pen is your best bet. I can't see the picture but i'm pretty sure those membranes are resistive and different resistances mean different keys (i may be completely wrong).

 

[TimHD]

Your links gives a permission error.

This forum is great, but man it's hard to get pictures in here! The link was to a My Gallery Page, that I have set to 'Public' so it should just work! Will try adding the picture of the damaged area using the 'My Media'  icon in the editor.. 

Hopefully you can see this image now..

[edit: I can see this after posting it, but let me know if still not visible]


Conductive Pen seems to be the best solution... (makes sense as the membrane wiring looks like those de-misters on the rear windows of cars)