I put together a video on youtube showing the different ways you can troubleshoot a failing/failed keyboard membrane and how it’s possible to test and maybe even fix it.
It’s a tricky business that’s for sure but if you want to give it a go then you’ll need some conductive pain, there are two main types, black or silver.
Below are some of the resources I used.
Here is an A4 sized graphical representation of the CPC 664 keyboard, simply save it and print if off to help with marking which of your keys are faulty. Via link.
Below I am testing the conductive paints, links to them below.
- Bare conductive paint (they have a problem with their website, but here‘s the link.)
- LeitSilber conductive paint – ebay
- Fluke 117 multimeter
I bought my new membranes from SellMyRetro here
and here’s the video link