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?


(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

!


(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?


(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?


(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