LED's In Cluster & Window Buttons

[autickfordfairmont]

Just a quick question, would you be able to put a resistor on the actual power line as it enters the cluster & the power window buttons so that you dont have to put one on each LED?

[KOUPE76]

Quick answer "NO".

[autickfordfairmont]

ok, next question, WHY?

As far as i see it you have a 12v illumination wire running into the cluster then off to the light globes, then back out on the - line. When you solder in your LED's with resitors on them your droping voltage down to 3v (or whatever the LED is) for each. If you drop it before it enters then theres no need for resitors on each one. I may be wrong, probably, it sometimes happens but just wondering why it cant be done?

[Steve_T]

Yeah, why no? If wired properly and you do the math right to work out the resistor required for the number of LEDs etc. it should be no prob. Only thing is you may loose brightness of some LEDs maybe but should be okay if you get the right spec. LEDs etc. yeah?

[KOUPE76]

Basically if they were wired in series I can't see why not (remember the old xmas tree lights? 1 globe blows then all go off : ), but they are wired in parallel (so when 1 globe blows the others stay lit) thus each led needs it's own resistance value of no more than +1% or no less than -1% or else the led would only last you a couple of hours then burn out.

It might sound like crap : but with the way the AU dash lights are wired they get their power from the cluster itself (no independant circuit) so if you do plan on doing that then who knows what it will do to the reading of you gauges or your power windows.
Electronics is a funny thing. :nutsycuck
Trust me I'm no electronics whizz but I am an electrician and have done alot of mucking around with leds and if all your figures are rite i.e voltage and resistance then you shouldn't have a problem.

Mick :

[Steve_T]

Yeah, I see what ya mean about 'em being parallel, but I still don't see why it wouldn't work - you just have to calculate the values different due to total resistance of the LEDs decreasing when wired parallel instead of increasing when in series. Use of a 1% tolerence or better resistor would be good also of course.

According to my workshop manual schematics (AU2), the cluster illumination gets it's power from the two standard interior illumination wires just like the rest of the interior illumination - it's independent of the rest of the cluster circuitry - I just had a look in the manual then for both high and low series clusters - the two wires (dark blue w/ red trace and brown) go into the cluster and feed the bulbs on their own just like everywhere else.

NB. I am assuming here we're only talking of LEDs for cluster illumination and not for the warning lamps - which would each need their own resistor of course.

There could be something I'm missing (a common occurance LOL ) but I think this would be ok.

Steve.

[AWD Chaser]

I do IT, Electronics and mechanics.

Fault Tolerance

For the extra few minutes of soldering up some resistors, it'll be peice of mind knowing that everything is gonna work.

[Steve_T]

Yeah, no doubt that doing 'em individually is the better & most reliable way.

Just as a follow up to my last post I'll link this circuit diagram...

http://www.fordforums.com.au/photos/...cat=663&page=1

Note that wire 19 which is listed as LB-R seems to be a typo - should be DB-R.

Steve.