Repairing Broken Mambrane Print

Hi all.

First of all, this is my first instructable and English isn't my native language so please be gentle.

I made this tut as first of a couple that will come. I want to make a simple robot with old electronics and I want to use an old ZX Spectrum as the main CPU. To do this I first modded the Speccie so I could plug it into the AV connector of the TV or a little monitor. I used this site for the mod.

http://womblesretrorepairshack.blogspot.com/2008/11/zx-spectrum-composite-video-mod.html

And off course as what in the disclaimer stood happens to me.

A quote of the website: "These keyboard membranes were never the most robust component and aged ones are probably more fragile - don’t strain or bend them ribbons."

After carefully loosen the ribbons the 5 pin ribbon did break. I though; "Dawm, how can I repair this. The ribbon is to short to be reattached."

So I will let you see how I did it.

Requirements:

- Sharp scissors
- A small Phillips screw driver
- Wire clipper
- Solder iron + solder wire
- De-solder equipment
- Old ribbon cable

First take a good look of how the connector is put on the printed circuit board (PCB), make notes or take a picture.
Then disassemble the print out of the casing by unscrew the parker in the middle of the board.
Flip over the PCB and de-solder the connector. Make sure the holes are empty, this makes things easier later on.

Now take your old ribbon and measure the needed length. Cut the desired length and strip the wires.
I uses tweezers to turn the treads before I pre-solder the wires.
Now, solder one end of the ribbon onto your PCB and solder the removed connector on-top off it.
Make sure you solder the connector correctly onto your ribbon, check your notes or the picture you've taken.

Take the foil ribbon and cut off right behind the baddest part with a sharp scissor. Cut it as straight as possible.
There was a plastic piece on the old ribbon. I took them apart and noticed that the plastic piece was still sticky.
I cleaned the remaining ribbon and attached the plastic piece back on it.

Now put it all together and test your repairs.

After hooking it all up and power it on to check my repairs, I noticed that some keys didn't work. So I look it up in the schematics and noticed that one line was still broken (in my chase, pin 1 of the 5 pin connector)
After I disassembled the keyboard to check what's wrong, the entire ribbon came off right behind the keyboard. So it was game over for me.

But there is a light at the end of the tunnel. Present day the membrane keyboards are still available for the ZX80 to ZX Spectrum.
Check out this site for more info:

http://www.rwapsoftware.co.uk