Foil ribbon repair , current state of knowledge of workaround fudge/kludge "repair" methods?

Oct 25, 2014 4 Replies
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Roland RD300SX electric piano of 2004, incidently very different from the RD300S on

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otherwise SM not found Meddling owner got inside to fix "scratchy" control. Removed all the under screws and then refitted mixing up PK and machine screws. Probably wrenched the 2 foil ribbons on taking the casing apart and then trapped a ribbon between a keyboard pylon and grounded aluminium foiled base chipboard. Intermittant loss of notes in the second octave. By the time I got inside , changed decay setting to maximum, and holding notes in that octave, no loss of any notes moving the cables, presumably as I wasn't in full flow and playing big heavy chords. Luckily not a CD sled type ribbon, and plenty of space here for a fudge repair. As one track on one edge only is damaged, as far as I can find , I'll try scraping back and mechanically bridging with cut-down phosphor bronze saddle from a small slide switch plus external clamping over that spot. I would normally fully disrupt the break and take a piece of enamelled copper wire from pcb to pcb, perhaps with a pair of turned-pin DIL socket socket pins to make a breakable union. (rather loathe to take a soldering iron to the main processor board) Anyone ever tried miniature rivets (good enough for pot construction), ?bridging with a piece of phosphor bronze strip from an analogue meter,say, plus mechanical clamping? woods metal low temp "soldering " over the break? ie anyone had success with some technique other than silver-loaded paint/car window heater-strip repair paint, which I don't think is reliable and don't use.


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Just in case anyone wishes to try similar. Razorred back the blue lettering side of the ribbon either side of break, made more definite, so cannot intermittently remake after this bridging Robbed slide contact from a new smallest size slide switch. Only a fine notch between contact faces, so stripped some seriously multistrand fine copper wire to loop into that notch. Twisted up and soldered off , to give some pretension to the contacts, ie to similar degree as the header contacts . Keep the excess wire in place to help sliding over the ribbon edge. Check for continuity. Swathe in hot-melt glue . Proof tested by checking continuity while locally bending, positive and negative, to about 30mm radius of curvature. Not that there is any bending, in use, just as some sort of integrity test. More generally within the width of a ribbon , perhaps, make a hole between conductors, cut in half one of these switch contacts , place over bared trace, pass copper wire loop through the hole and twist up against tiny washer and solder off, cut off excess wire. I wonder if anyone has tried "cigarette paper" spot-welding a bridge connection on a ribbon cable. A thin bridge strip clamped in place over a barred trace , with some thin cigarette paper , in between. Connect a high A, low V transformer (+diodes?) to it, with a current monitoring relay mains cut out. Clamp up tighter until the current bridges the gap and forms some sort of spot weld. Repeat for the other contact. Would it fail in similar fashion to trying to solder to such ribbon traces?

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Your post was not understandable.

Did you fix a broken copper foil?

Mikek

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I would estimate the "insertion force" for sliding the 2 contact modified ex-switch contact over the edge of the ribbon was about 1/4 to

1/10 of the force required to insert the 22 way ribbon in its header, so similar or greater contact force for the "repair"
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