Repairing Broken Mambrane Print

Introduction: 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.

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.

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Step 1: Parts List


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

Step 2: Lets Heat the Iron

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.

Step 3:

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.

Step 4: Snip Snip

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.

Step 5: Reassemble

Now put it all together and test your repairs.

Step 6: Edit, Epic Fail :(

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:

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    Great idea ,even if it didn't work out for you. There is also a substance called "Wire Glue" (eBay) that lets you connect wires to these flexible PCBs without the heat of soldering. I've repaired several solar cells with it & it is suprisingly strong. Hope this helps someone.