Repairing flat cable

isw wrote in news:isw-0C56E4.21390421122008@ [216.168.3.50]:

Low melting point, 117 C. Not likely. Perhaps PEEK

Have you tried a razor blade along the surface of the conductor? You may be able to mechanically split it away from the conductor.

How about grinding it away?

HOT Di-Methyl-Formamide (DMF) will breakdown most plastics but it can be rough on metals also. It is also nasty stuff to work with. A well equipped chem lab, Gloves, hood, face shield, apron. In the late 60's, when I worked for Sprague, we used to use it to remove molded epoxy cases from capacitors so we could do fault analysis on the ceramic chips.

The plastic can often be 'stripped' with a blunt(ish) curve-bladed scalpel, scraped across the surface, with it on a flat hard surface such as an old ceramic tile. Having said that, I have found that the orange ones such as you used to find in Panasonic answer machines and on Pioneer lasers, are much more resistant to any kind of stripping, than the white ones. You might also try ally oxide paper such as you might use for flatting a paint surface on a car body.

If you manage to get a connection that works ok, I would suggest that it is then covered with something like a bead of silicone rubber (not the bathroom sealer type which releases acetic acid as it cures) to help relieve any stress on the joints, if it is in an application where it flexes in normal use. If it is not, and you can't get a good connection, you could consider just hard wiring between the two boards that it connects. If it is socketed at both ends, replacement flexiprints in many different pitch, ways and length configurations, are available.

For instance

Arfa

A small cylindrical centrided burr in a dremmel can be useful for stripping back, surprisingly controllable if you hold it the "right" way round so it doesn't skud.

Or make up some fine wire plaited braid to replace the whole thing

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

It's in the lens assembly of a small camera. The cable is less than 0.25 cm wide, and has twelve conductors (I had to use a loupe to count them). Making a replacement is probably not in the cards.

Isaac

Tried scraping, sanding, and abrading with a rotary abrasive-fiber wheel

-- everything I tried destroyed the traces...

Isaac

Don't you just HATE that sinking feeling you get in your stomach when something like this happens, especially when it's a customer's unit ... :-(

Long experience of working with flexiprints of all descriptions, leads me to believe that you are really going to struggle to reliably repair one that small and fine-pitched. I suppose it would be really silly to ask if there's any chance at all of getting a replacement ?

Arfa

I have seen these replaced by insulated winding wire, e.g. from a relay coil (maybe 0.002 inch or 50 micron wire). On the other hand I would not do this for a customer since it may not be reliable in the long term. It might be worthwhile for fixing you own stuff, however. Chris

Yeah, and especially because I've fixed two of these cameras previously (there's a design weakness in a supporting strut inside the lens; a bit of brass tubing and some epoxy is all it takes). This time, the strut was fine but somebody had spilled something like orange juice in the camera, and the moving parts got all gunky and sticky. I think that's what tore the cable.

The only way would be to get a good cable from another scrapped out camera (which this one now is). The cable terminates on the "sled" that carries the anti-shake lens, and the driving coils for that are etched right onto the orange plastic substrate; there are not any "terminals" to attach replacement wires to...

Isaac

Ah well, some ya win, some ya lose ... At least if the owner has filled the thing up with juice, there's justification for declaring it BER, and at least it's not a problem that you have caused whilst repairing some really simple thing. That one's the killer. When you've fixed the dirty volume control with a lttle squib of switch cleaner, and then you drop your screwdriver into the output stage ... >:-\\

Have a good 'un

Arfa