Need to fix hole in ribbon cable

How many conductors are there in the cable, and do you know how to solder?

at

Can someone tell me what this

Thanks for posting.

There are 2 wires that come out of the blue connector, so I guess that means 2 conductors. That's part of what makes me confused, there only appears to be one cable zig-zagging through the wire, but on closer examination, the zig-zagging part is clear. And yes I can solder.

Francis

WHat you have looks like a rectilinear sensor.

I used to work for a company (

) that used to make these similar types of parts. They are actually silver and carbon conductive elements that are silkscreened onto plastic. You cannot solder this. It called a"Linear Potentiometer" or "Flexible Printed Circuits" or "Membrane Switch Technology" Remeber the old Atari 400 Keyboards?

The connector is a form of a BERG connector

Depending on what your bugdet is or how bad you want it fixed i bet

can make one for you.

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ide quoted text -

But if the hole cut thru any of the conductors, like it appears to do, the OP will have to reestablish continuity by soldering a wire to each end of the broken path to reestablish the continuity.

at

Can someone tell me what this

text -

The OP stated (*EMPHASIS* added by me): >>> appears to be one cable zig-zagging through the wire, but on closer >>> examination, the zig-zagging part is *CLEAR*. And yes I can solder.

The zigzag is clear and is extremely unlikely to be a conductor. There are two contacts described at the blue end. I therefore concluded the white/silver strips with interlocking fingers were the conductors, which would suit capacitive proximity sensing. *NOTHING* will need bridging and soldering that sort of cable *will* destroy it unless the OP has an extremely delicate touch.

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Your a better solderer than I if you can solder to plastic!!!!!

Been there, done that. Sinclair keyboard cable repairs. It can be done but the success rate per joint is sufficiently low that repairing anything complex is totally impractical, You need *extremely* flexible wire to stand a chance of it working and even so the repair is incredibly fragile. Also its 'kill or cure' as the slightest mistake and you've melted through the plastic. I'd rather clean a swimming pool with a toothbrush, it would be less frustrating . . .

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Conductive paint?

I want to thank everyone for posting. I want to make sure I understand what everyone is saying. There are 2 "wires" with little teeth. Each wire looks like:

____________________ | | | | | | | | | | | |

It looks like I damaged some teeth, but not the main part of the wire. Yet it's still not sending signal. Does every tooth have to be there?

Something I else I'm wondering, since the damage is near the end of the cable, could I just cut off the damaged portion and reattach the connector? I have enough slack for this. If I try to remove the connector, it will probably ruin it, won't it? Also, I don't know how the ribbon cable hooks to the connector. Any thoughts?

Thanks again, Francis

Probably not, especially if this part isn't under any keys. Just to eliminate the more insane possibilities, can you confirm that this cable is only connected at one end?

If you powered it on with the screw through the cable, its possible you damaged the circuit that this sensor connects to. Its also possible you have a short circuit in the cable due to the damage, but I don't think so looking at the photo. Is there any evidence of damage to the blue connector or the mating socket caused by the cable getting pulled as the screw went through it?

Its likely the contacts on the cable were crimped in place and then the blue plastic was either moulded round it or otherwise bonded. I wouldn't try dismantling it without a quote for a replacement in front of me. If it is a capacitive sensor, shortening it by more than a very small percentage of the total cable length may put the circuit out of adjustment and prevent it working anyway.

Check the resistance across the two contact pins on the cable with it disconnected from the board. If my suspicion that its a capacitive sensor is correct, the resistance should be higher than a good multimeter can measure. In that case, connect a capacitance meter, and see if the capacitance changes noticeably when a small metal object (e.g. a coin taped to a biro to let you move it without getting your hands near the circuit) is placed against the cable surface. You will probably only get a change of a few picofarads. Try either side of the damage.

I think that it probably calibrates the sensor when it's switched on and if you allow the cable to move while you are testing the complete unit it may go out of adjustment and so not work. Did you try it out with the lid *ON* (you don't need to put all the screws back in)?

Also what was the fault or reason that made you open it to start with?

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Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
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It will ruin it. The connectors are applied with a special tool.

On Fri, 02 Jan 2009 18:08:03 GMT, snipped-for-privacy@xmission.com (GMAN) put finger to keyboard and composed:

I can see how the membrane pot works ...

... but how would it sense pressure?

The OP's cable appears to have two adjacent conductors with interlocking fingers. If the cable was a Hotpot, wouldn't both conductors need to be directly above each other?

- Franc Zabkar

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OK,

I decided to take apart the connector. The blue part was just a plastic holder. Inside were 2 metal pins hooked to each side of the cable. For lack of a better term, they were basically stappled into each of the two "wires". Seeing how it was connected, I got inspired. I bought a connector like you see at the end of an IDE connector. This one had 8 pins, so I removed 6 of them. I cut off the wire and discarded the portion with the hole in it. I was able to punch the pins through the wires just perfectly but it still didn't work. So it's starting to look like there is a problem somewhere else in the wire.

Since getting taking the wire out would involve literally hundreds of screws, I'll wait till I have to go in the keyboard for some other repair. I guess I can live with it for now.

Thanks to everyone for their great advice.

Francis