Powerbook Duo 280c + Accessories Maintenance

ok, one keyboard messed up 😂..

IMG_6971.jpg IMG_6972.jpg

maybe I overdid the tracing, whatever, it doesnt work anymore.

thinking about the actuall (stupid) physicality behind the usage of two foils over another, the thing that is making the contact actually is the ring inside the rubber dome ..I think.
havent taken a photo of it, but inside the rubber dome seems to be a contact ring ( maybe with a conductive paint of some sort), so using th conductive paint there also is an option

this guy used a pencil eraser to clean the traces

Bildschirmfoto 2026-02-25 um 13.15.47.jpg
have a second keyboard with much nicer state of the foils but multiple rows are not responding..checking the ribbons again
 
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The contact ring inside the dome should be conductive, and when pressed, should bridge the two contacts.

Things to watch out for with the pen: 1: don't bridge the traces, and 2: don't get too close to the key contacts.

I use a pink pearl eraser to clean the contacts -- cleaning the traces shouldn't be needed unless there's a fracture, in which case you clean first (99% IPA), dry, and THEN use the pen over the area to ensure any breaks are bridged.

The goal is to have lowest resistance possible from the contact end of the trace to the far end, and to have the contact ring being the ONLY thing bridging the contact to the trace.
 
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