Make a New Mylar Keyboard, was Re: Commodore 64-sx Keyboard getting stuck?

Marvin Johnston marvin at
Mon Jul 11 23:16:33 CDT 2005

Since I suspect that the keyboards were originally done by silkscreening
conductive ink onto mylar, it should be fairly easy, albeit time
consuming, to make a new mylar. My guess would be to use something like
a Houston Instrument Pen Plotter that would also take a vinyl cutting
knife, cut out the mylar, make up a screen, and just silkscreen the
traces onto the ready to insert mylar. Or, if the old mylar is not
broken, just reuse the old one. I don't know what kind of prep needs to
be done in order for the ink to adhere to the mylar, but this (and
anything else that comes up) is something that has been done for a long

Another thought would be to go to someone who already produces this type
of switch and find out what it would cost to make up a couple. It might
be possible (depending on the size of the company) to get it done
gratis, ie as a sample.

> On 7/11/05, Dwight K. Elvey <dwight.elvey at> wrote:
> > If that didn't work, a last resort might
> > be to use some small wire wrap wire and melt a channel
> > into the plastic layer to keep from deforming the stack
> > too much
> I've seen the results of attempts at that.  Let me put it this way -
> try it right before you are ready to pitch the whole mess.
> there's not enough pressure to make contact between oxidized traces
> printed on mylar and any kind of wire.  The mylar sheeting is thin
> enough that you are more likely to perforate the mylar than "melt a
> channel"  _Perhaps_ some kind of foil overlay might work, but it would
> have to be akin to gold leaf, and you'd need a solder alloy that
> melted below the temp of the plastic to get any sort of joint.  For
> that matter, if you had an uber-low-temp solder (200F?  300F?), you
> might be able to overlay entire traces with WW wire, but not if the
> plastic develops holes.
> -ethan

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