Foil ribbon repair , current state of knowledge of workaroun

[N_Cook]

Roland RD300SX electric piano of 2004,
incidently very different from the RD300S on
http://www.synfo.nl/servicemanuals
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.

 

[N_Cook]

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?

 

[amdx]

On 10/26/2014 4:28 AM, N_Cook wrote:


Your post was not understandable.

Did you fix a broken copper foil?

Mikek

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[N_Cook]

On 26/10/2014 22:16, amdx wrote:

On 10/26/2014 4:28 AM, N_Cook wrote:


Your post was not understandable.

Did you fix a broken copper foil?

Mikek

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protection is active.
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yes

 

[N_Cook]

On 26/10/2014 22:16, amdx wrote:

On 10/26/2014 4:28 AM, N_Cook wrote:


Your post was not understandable.

Did you fix a broken copper foil?

Mikek

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protection is active.
http://www.avast.com

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"