Need some ideas to repair the fibre optic panel illumination

(David Judd) #1

I have a 1975 XJ12C that needs some repair to the fiber optic system. Some of the ferrules have come off the end of the optic “wire” and I would like to repair them. I have gouged out the remaining stub of the optical element and reinserted the end of the of the element into to ferrule but no light. Any Ideas?

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(Aristides Balanos) #2

David,

It’s not very easy to repair… the ends of the fiber cable have to be highly polished otherwise light won’t come out. Same if there is a break somewhere in between.
I’ve ditched the fiber optic in my SIII and replaced it with green miniature LEDs.
The LEDs fit exactly in the fiber optic hole, the only pain is the wiring, the wires have to be the thinnest possible as they are quite a few LEDs (seven in total I think) and by the end you have a big bundle of wires.
The result was very rewarding though as now the fascia controls actually illuminate !

Aristides

!

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(David Judd) #3

Aristides,

I read some old posts about doing this, but not being and electrical engineer I didn’t grasp the necessary resistors to get the voltage down for the LEDs. Care to explain it to a shade tree restorer in layman terms?

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(David Jauch) #4

You can get the LEDs with resistors as a bundle online! Apart from that you should be able to search google for what needs what to get a LED to run on 12V. The resistors need to drop the voltage to what the diode likes and more importantly limits the current. Worst case they get hot and blow…
Is it the 1.8mm that fit? Thin wires should be no problem, after all one can run to a close ground anyways? Not that it would be needed. I think there should be enough space?

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(Aristides Balanos) #5

David,

The LEDs should be 3mm.

You just need to put a 1/4W - 800Ohm resistor in line with the LED.
You can experiment with the resistance, 600 ohm will also do and they will be slightly brighter, or 1.5kOhm if you want them less bright, but that will depend also on the LED’s characteristics.
You could also put just one 2W resistor for all of them or even a 2kOhm potentiometer so you can adjust the brightness.

They also make them for 12v now days…

There is enough space if you use thin cables.

Aristides

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(Roger Coole) #6

If the fibers are still good, how about installing a brighter LED source for them? If it’s one for 12V that’s dim-able then would the rheostat still be ok to use?

Roger

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(David Jauch) #7

NI have, get the brightest front-firing one you can and I doubt it’ll even have to be dimmable. Maybe mine dims, I need to check.
Do not use a higher wattage incandescent because of the heat.
My cables are somewhat brittle and I suspect cutting them with a sharp knife, rather nicking and then snapping, might be okay?
They had to have had an easy way at the factory… or sand and then a hot plate to push against?

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(Roger Coole) #8

Might be able to get one here.
https://www.superbrightleds.com/vehicle/1987-jaguar-xj6-vehicle-led-lights?make=38&model=1776&year=1987
I replaced my map, B pillar, and trunk lites with LED’s. A word of caution, they had sent me the wrong size and had to return them. Wasn’t any problem though. They were good about it.

Roger

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(Frank Andersen) #9

**
I think a sharp(!) knife is the way to do it, David - the ends must be smooth. Shouls be some write-ups on it out there…?

Frank
xj6 85 Sov Europe (UK/NZ)
**

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(Aristides Balanos) #10

I have tried once and didn’t work… The end has to be highly polished and even though having all the polishing tools I did not succeed in repairing it. I will confess that the LEDs idea was already on my mind, so I gave up after the first try.

I have a complete set in good working order if someone is interested, cell and fiber optics.

Best,
Aristides

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(David Jauch) #11

I mean truly snapping it, just a nick with the knife!
As long as everything works I won’t try though.-

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(Con Saris) #12

Do you know anyone who has experience in terminating and joining fibre optic computer networking cable? I think that may be only way to get a truly clean cut end. From what I gather this requires specialized tools and a very clean environment. Here in Australia we are trying to drag our internet infrastucture into the 21st century. I see vans on the side of the road where the fibre optic cable enters at the front and leaves at the back and some where in between it is joined to provide a continous cable. Don’t think there is a joiner involved.
Con

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(Andrew Waugh) #13

I’ve used the fiber optic interconnect “cable” used for connecting audio equipment as a source for illumination FO on a few projects. They’re single channel, 2.2mm dia. Iirc the cables are about 20$ for a 2m one.

I just cut the ends with a sharp knife, then polished with W&D to 1000 grit. To connect to the LED I sanded and polished a flat on the end of the LED, then glued the fiber to the LED, and stabilized it with heatshrink.

If I had to do it again I would buy or scavenge an LED with the correct FO connector - they are usually red, but you may be able to find shells which accept a standard LED, so you can pick and choose your colours.

The FO only needs to be optically polished if you’re trying to send data down it, for illumination “shiny” is good enough.

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