I’m having a fair amount of trouble with my new Knock Link and I’d sure value some help.

I’ve taken the LED’s out of the box and stuck them on wires so that I can mount them remotely. My first problem was that I forgot that LED’s only work one way but I’ve now rectified this (thanks to Andy Tang) by making sure that the smaller tab inside the LED is connected to the common rail.

My problem now is that the large clear LED doesn’t light. The sensitivity is set on max and I can easily light the others. I’ve used a multi meter to check continuity of the LED connection and it all checks out from the chip to the common rail. I’ve also checked the LED’s integrity, which also seems fine.

I’m left with two conclusions and neither seems likely.
1, the large LED works the other way around, so is wired wrong

2, the other is that the power supply (*** lighter) is too weak

Is there anything else I’m missing - help!

 

are you sure the sensitivitys up to max if its max then the big LED should light when you tap the sensor gently, if not check the solder points and get a 9 volt battery and connect straight to the legs of the LED making sure youve got the correct polarity if that doesnt work then the LED is fooked

 

Thanks cong

Sensitivity - yup it's turned fully clockwise (pointing at 11 o'clock)

I've also checked that the LED still works and it does.

 

Agree with the above, double check the red LED actually works, if not it's a quick trip to Maplin and sorted. Or if you can be bothered, try swapping the red LED with either a green or amber one and see if they both light up.

Also have you double checked the tracks as they break easily. It might be worth soldering the wire closer the the chip (? - sorry it's been a while since I've dismantled a KL) and therefore bypassing the track completely.

I've heard of someone who had the sensitivity the wrong way round on their car, so try turning the sensitivity the other way to see what happens.

It might be worth taking the power feed from the back of the stereo, but I doubt that would make any difference as you've proved the other LEDs are lighting ok.

 

Unless the LED has an internal resistor I wouldn't stick 9v across it.

 

Thank you both.

I've tested the continuity to the LED by placing the probe on the LED leg and the other on both the solder joint and the chip leg - so it should be fine.

Thanks for your help once again Andy.

 

Rock on it finally works

I thought 'lets just check try the big LED the other way round before I start rewiring the power supply' and hey presto it works. While do I enjoy modding so much? When I'm doing it it completely does my head in because it never goes right, but afterwards I always think 'that wasn't too bad!' I must be an idiot

Thanks for all your help.

 

Phew!!

And in time to give it a proper testing!

 

Dead right Andy, proper testing tonight at the Essex tunnel cruise!

Took it out for a spin this afternoon just to see if there was any activity. I gave it a reasonible belting and not a dicky bird When I got home I put a spanner on the bolt and tapped the top of it, it lit up like a Christmas tree - hurray! Chris at PE must have done a good job on the mapping

 

On Knocklinks, the "big red LED" is a reverse anode type. They denote this by putting a red dot on the "large lug" inside the LED casing, to let you know it's positive, and not negative.