Replacing alarm LED

eidolon

eidolon

eidolon

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Joined
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Newcastle upon Tyne
I've got an Acumen Cat1 alarm on my bike however the LED has packed up. As there's a ****** 2 mins down the road I was gonna pop in and pick up a new one but I have no idea which one to buy.

Does anyone have an idea how I find out what type I need? Is there likely to be anything on the LED itself which will give me a clue?

EDIT : I guess the popular electronics component retailer is a naughty word....
 
I'd presume, if you can get the LED out, that the bloke at the 'reels of wire and leds and resistors and stuff' desk/dungeon at the back of the aforementioned high street electronics place would be able to ID it.

However... don't LEDs very rarely go? Could it be something else?
 
LEDs are what I do :)

Just replace it, really straight forward if you can get it out
On a new LED you have a positive and negative, (cathode and ground)

easiest way to remember it is the long leg takes the power (positive)

you can solder the resistor (about 100mh) to either leg although some prefer certain legs, i personally solder the resistor to the positive,

thats the hardest part, once the resistor is soldered to the LED, just match the positive and negative of the wiring loom to the old LED on your bike to your new led and resistor combo

if there are no coloured wired on your old led, look at the base of the plastic lens on the old LED, the negative/ground should have a flat spot next to it
 
I think on all my bikes the LEDs for alarm have failed. Reason is they generally are just fitted by a shop and as they are on bodywork the constant vibration just snaps legs off them rather than the LED chip itself going faulty.

Replacing is quite straight forward though it's probably more trouble than it's worth...

Reason is that you have to establish how the alarm is feeding the LED... all LEDs need to be current limited so it's possible the alarm has the current limiting resistor internally. I very much doubt you'll find a resistor soldered to a leg of you current LED.

The other possibility is the LED on the bike has a built in current limiting resistor.. but these are expensive so unlikely to be the route the manu went


I would just leave alone tbh, unless you call up the alarm manu and ask them how the LED is fed... once you know this it's a easy job though :)


If you went ahead and chose a LED / Resistor and it turns out the Alarm already has a resistor internally your LED would be very dim / not light at all..... if you connected a LED without resistor and it turns our the Alarm doesn't have one either you could possibly destroy your alarm.

If you want to have a bash get a resistor of around 1-2k range I guess.... this would limit current to around 10mA at 14.5V, if it lights but very dim, just halve it's value (and assume the alarm is also limiting). The current you 'set' though depends on LED type used.


edit: if the above blows up your alarm it's not my fault lol.

edit edit: you might just get away with buying a 12v LED (with internal resistor), maybe enough to light even iif alarm already has one... it's probably the safest route where you can't do any damage.
 
Last edited:
Flukester said:
edit edit: you might just get away with buying a 12v LED (with internal resistor), maybe enough to light even iif alarm already has one... it's probably the safest route where you can't do any damage.
Click to expand...

I think I've got a 12V LED in the garage somewhere so will just plug that in first to see if it glows up at all (I've traced the wires from the alarm to LED so shouldn't be too much trouble swapping over)

Cheers
 
I tried the 12V LED I had lying around and it flashed fine when I first arm the alarm, then after about 10 seconds it just stops completely. At least I know that the output is ok, just need to sort a proper LED now.
 
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