Sean said:
I thought the same thing, but I can't see how conductive paint can be
used when the whole thing is insulated.. it's basically flexible PCB.. I
have ended up cutting it back but that doesn't help because now I've lost
the gold connectors..
I'm guessing there's no way to fix the cable now!?
If not, can this sort of cable be bought.. is it standard!?
Thanks,
Sean
If its water clear plastic the method below WILL NOT WORK
(plated/conductive ink tracks and low melting point plastic), but at this
point you have nothing to loose so try it anyway. It also works for the
white ribbbon cables with the pretinned conductors but skip the tinning
step below (a *brief* touch with an iron can help you scrape off the last
of the white plastic but always risks lifting a track)
If its all a sort of golden yellow colour, the cable is almost certainly a
Kapton substate flexible PCB with an additional layer laminated on top.
AS LONG AS THE TRACK SPACING AND ORDER IS IDENTICAL AT THE BREAK AND THE
END ITS FIXABLE.
Take an *ADJUSTABLE* Dremel tool (actually the really cheap clone ones
with the external powerbrick works fine for this sort of stuff, fit a
small ball ended DIAMOND burr and turn the speed down pretty slow. Take a
fine tipped pen (e.g. CD marker) and mark off the length you need to
strip. Grind off the top layer from each contact one at a time. Keep the
burr moving around all the time or you will go right through. When you
see a spot of bare copper, work around it, dont go back over it because
its VERY thin. Its best to work against a slightly resiliant backing such
as a block of expanded polystyrene or a pencil erasor.
Finally finish by fluxing the contacts with a flux pen or some liquid
rosin flux and tinning all the contacts (very little solder, fine tipped
iron and *very* brief contact. Any small remaining sport of Kapton can be
cleaned off the tinned surface using a small jewlers screwdriver with the
end ground at an angle as a knife blade, edge at 45 deg. to shaft and
about a 30 deg included angle at the actual cutting edge. Sharpen on a
fine india stone or 600 grit wet & dry paper using some light oil.
(usefull general purpose tool when patching fine pcbs) Scrape very gently.
Clean up excess tinning with fine desoldering braid ( braid touching the
tip, then briefly wipe the contact with the braid still touching the tip)
Trim back to fresh braid for every contact. If you've done it right none
of the tracks have lifted. I've had some success sticking one or two back
down with a tiny drop of superglue applied with a toothpick and hold the
track down gently for five minutes with a very small screwdriver or the
point of the scraper mentioned above.
Finally, if there is a backing strip on the original connector, strip it
off carefully using a thin sharp knife to worry at the glue line (or even
the above scraper again). Remove any residual glue with some solvent and a
cotton bud. Roughen the surface with the diamond bur on really slow and
do the same to the back side of the ribbon cable Stick in place with a
tiny drop of suitable glue (I dont like superglue for this, it doesnt
stand up to being flexed and it tends to get on the track side and rip
tracks off when you take the clamp off) Clamp flat till fully dry. Clean
the tinned contacts with isopropyl alcohol or methylated spirits and a
cotton bud. Apply the lightest smear of a good contact cleaner/lubricant
(to slow down the inevitable tarnishing) and insert into matching socket
and pray to Deity of Your Preference
I STRONGLY reccomend practicing on the scrap end you cut off. DONT strip
the wrong side of the cable (LOOK AT THE SOCKET CONTACTS!). I did a £1000
proffesional video head last week and it took me about an hour for about
20 contacts. (now that was really fiddly, grinding cables 1" away from a
really delicate head drum and having to keep both head cables (both
damaged) the same length to maintain rotational balance)
--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
[dot]=.
*Warning* SPAM TRAP set in header, Use email address in sig. if you must.
