Sinclair Spectrum keyboard ribbon cable

[Dave Moll]

I have several Speccies with the same problem - one (or in one case, both) of the ribbon cables going between the system unit and the keyboard have broken. Is it possible to repair these - given that I have both halves of the cable?

For those not familiar with it - this consists of a plastic film with metal strips embedded in it similar to those found in banknotes.

[G8KBG Tony]

Some information here.

[Dave Moll]

Thank you for reminding me of that thread. Although it was a ZX81 in that instance, they do Spectrum membranes for the same price, so I have ordered one - and may order a couple more to get the others working if this is a success.

At that price it probably isn't worth faffing about with repairs - though has anyone tried it?

I had a feeling there had been a recent thread about ZX keyboards, but a forum search on "spectrum keyboard" failed to find anything - now I know why!

[David G4EBT]

Originally Posted by Dave Moll

Thank you for reminding me of that thread. Although it was a ZX81 in that instance, they do Spectrum membranes for the same price, so I have ordered one - and may order a couple more to get the others working if this is a success.

At that price it probably isn't worth faffing about with repairs - though has anyone tried it?

I had a feeling there had been a recent thread about ZX keyboards, but a forum search on "spectrum keyboard" failed to find anything - now I know why!

Membranes are an easy and quick fix.

In the late 1980s, I repaired many spectrums that had been scrapped as beyond economic repair - I often picked them up for a couple of pounds at car boot sales, and bearing in mind that a 16k specturm back then cost £175, I could sell as many as I could get for £75 each.

They had two common problems:

1) the keyboard membrane, on which the tracs are a sort of conducivesilver paint prnted on, used to get hairlne fractures at the point at which it fitted into the socket on the board.

2) Kids often used to fit the joystick controller on the back of the Spectrum when it was switched on, which used to kill the CPU. The CPUs were quite cheap but were 28 pin, and soldered directly into the plated through board.

I didn't attempt to use a solder sucker - I snipped off the CPU at all the pins, then using forceps on each pin left in the board, melted the solder and pulled out the pin. Always the best way to remove a duff IC, as doing it that way it took only a second or two per pin. (The IC doesn't then act as a heatsink, thus calling for the iron to be on each pin for a few seconds, risking damage to the board).

It was a nice little earner while it lasted!

Later, I used to upgrade the rubber keyboards to the new style black keyboard with "clicky" keys.

Unbelievable that relatively speaking, allowing for inflation, today, you'd get a 500GB hard drive, 4GB Ram, a Core due intel processor, wireless keyboard/mouse, and 19" flat screen monitor, and W7!


Best of luck.

David,
G4EBT

[dominicbeesley]

I had one bodged together with cellotape and strips of kitchen foil for years as a kid. I had to shine up the traces first - I just scratched at them with a butter knife then stick the replacement strips over them.

It needed periodic faffing with. I've still got the machine here somewhere must see if it still runs one day....

Dom

[Dave Moll]

I might have a go along those lines, though I would be inclined to use the Scotch "invisible mending" tape (which doesn't dry out the way Sellotape does). After all, with an otherwise dead membrane I've nothing to lose.

[David G4EBT]

Originally Posted by Dave Moll

I might have a go along those lines, though I would be inclined to use the Scotch "invisible mending" tape (which doesn't dry out the way Sellotape does). After all, with an otherwise dead membrane I've nothing to lose.

I guess that for hairline cracks in the tracks where they usually fail (at the socket where the membrane pushes into the socket on the PCB), you could use silver conductive paint, but a little bottle with no more than a thimble full, costs several pounds (probably more than a new membrane) and has a limited life.

The Spectrum was a triumph of simplicity of design - not least the keyboard itself.

There must be untold thousands gathering dust in lofts, waiting to be discovered, but probably destined to an undignified end in a skip.


Best of luck in your endeavours!

David,
G4EBT