"Fixing" Model M Membrane Connector Contacts

[mcdonc]

So recently I bricked a Model M while making some modifications to it.  It turns out I didn't brick it very thoroughly, though.  I just got some epoxy on the contacts that go to the controller from the membrane.  Because I'm an idiot, to fix that, I took a bit of sandpaper to the places where the epoxy got on the contacts and scrubbed all the epoxy off, along with parts of some of the traces.  When I held it up to the light I saw plastic and daylight in places there should have been metal.

Realizing my mistake, I trimmed a bit of the connector off, as I managed not to scrub off the exposed contact metal nearer to the internals on all of the pads.  That works, except now I have to keep the connector propped in a "just so" position with a little bit of cardboard for all the keys to register properly.  I'm wondering if there's some more permanent fix I can do to this thing short of replacing the membrane; like maybe expose some more of the traces by using acetone or something?  Or spread some very thin coating of solder down on each trace (like the game Operation!)  Any ideas?

[dmw]

Any chance you could post a picture of the damage?

[Findecanor]

Cured epoxy is resistant to most solvents, so the only way to get it off is either mechanically or softening it with heat. But heat is out of the question here, so it seems to me that you did the only thing that you could by using sandpaper.
Before it has cured, you can dissolve it with water, though.

If you want to paint new traces, then perhaps you could use some conductive type of glue as paint. Just an idea. I have never tried the stuff, so I can not recommend it.

[Voixdelion]

Cured epoxy is resistant to most solvents, so the only way to get it off is either mechanically or softening it with heat. But heat is out of the question here, so it seems to me that you did the only thing that you could by using sandpaper.
Before it has cured, you can dissolve it with water, though.

If you want to paint new traces, then perhaps you could use some conductive type of glue as paint. Just an idea. I have never tried the stuff, so I can not recommend it.

Get a "circuit writer pen" Highly recommended and effective for just such applications.  Available from Radio shack for @ 10-13 bucks in store or on-line also at Amazon.  I bought one of these years ago without having a need for it at the time, just thought it might come in handy.  Now after all the repairs I have effected to Playstations and other odd things as well as membranes in keyboards and punctured circuit traces on hp multifunction devices that would otherwise have found themselves in the trash I will not be without one in my tool box, and my friends have all acquired them after learning by what magic I was able to resurrect their devices.  I'm surprised more folks aren't aware of these by now:

http://www.radioshack.com/product/index.jsp?productId=3964901&CAWELAID=468196883

[didjamatic]

I'm getting one of those pens for sure!

[Voixdelion]

You can use some packing tape or the like to patch any missing plastic  and then redraw the trace with the pen.  I actually used this method  when I did something similar whilst cleaning the membrane of one of the  cheapo boards that I used to use.  Worked great, no soldering necessary  and easy to keep the traces separate by using the edge of a razor or  tape if several are close together.  Practice first though, since  getting the flow right is a little tricky at first.  If you want a  really thin line, I suggest unscrewing the base of the nib and using a  needle dipped in the liquid in the pen to prevent gushes or runs which  are less predictable through the dispensing end than if used "quill  style".

[mcdonc]

Get a "circuit writer pen"

Perfect!

[dfj]

I'm getting one of those pens for sure!

if you can't find the pen for a sane price, automotive supply places will carry 'rear-windshield defogger repair kits' which is a little jar of conductive ink. it looks copper, but is actually silver dust, copper plated.

about a third of the price of the pen (which is still awesome, and the best  solution) where I am.

just so's you know.
dfj

[Voixdelion]

Score!  Didn't know about that... always good to have alternatives.