Neutral switch issue

jerry · 12-01-2021, 12:12 PM

i now have a nice LED dash with Tacho for my M750 every thing works fine except the neutral switch which stays on when in gear , the circuit is ok as is the switch , but it needs a resister as the switch is old and not giving correct resistance for LED on dash panel now , normal bulbs it works with , i dont want to spend £30 on a new switch ,,

pooh · 12-01-2021, 12:29 PM

Chances are you are switching the positive through the switch not the negative I had the same problem with my Koso dash. Which dash are you using?

Pooh

Dukedesmo · 12-01-2021, 05:09 PM

Quote:

Originally Posted by pooh

Chances are you are switching the positive through the switch not the negative I had the same problem with my Koso dash. Which dash are you using?

Pooh

Possibly, I had to alter the wiring on both my 916 and Monster to work with a Translogic dash as the dash needs a negative and both my bikes switched the positive.

Although, with the Translogic it doesn't show 'N' unless the polarity was correct, rather it would show - - unless it detected a gear.

If your bike has a 2-wire switch then it switches the positive, 1-wire switches the negative. Older bikes used the 2-wire system, not sure when they changed to the single-wire, negative though?

Darren69 · 12-01-2021, 06:16 PM

Quote:

Originally Posted by Dukedesmo

Possibly, I had to alter the wiring on both my 916 and Monster to work with a Translogic dash as the dash needs a negative and both my bikes switched the positive.

Although, with the Translogic it doesn't show 'N' unless the polarity was correct, rather it would show - - unless it detected a gear.

If your bike has a 2-wire switch then it switches the positive, 1-wire switches the negative. Older bikes used the 2-wire system, not sure when they changed to the single-wire, negative though?

This makes sense because unlike a bulb that will light up whichever polarity is used, an LED will not.

pooh · 12-01-2021, 07:32 PM

Standard Monster neutral switch is single wire which makes a contact to earth when a gear is selected they work the same way as the oil switch it just supply’s an earth to the bulb or LED.

Jerry I’m not sure what you mean the switch has the wrong resistance? It is an on-off switch there is no resistor except the one that would come within the dash to reduce the voltage from 12v to roughly 2v for the LED.

Pooh

Luddite · 12-01-2021, 10:01 PM

If you want to calculate the value of the necessary resistor, you'll need to know the voltage and current of the LED you're using.

Then you can use this calculation to determine which resistor you need.

R = [V (Battery) ➖ V (LED)] ➗ I (LED)

So, for a typical standard LED with a forward voltage of 2V and a current of 20mA, the necessary resistor would be:

[12V ➖ 2V] ➗ 0.02mA = 500 Ohm

An extra bright LED may have a forward voltage of around 3.2V so the required resistor for that would be:

[12V ➖ 3.2V] ➗ 0.02mA = 440 Ohm

The resistor should be wired in series and is not directional so it doesn't matter which way round you install it.

jerry · 12-01-2021, 11:36 PM

bike has one wire to neutral switch changing polarity on the Contagiri dash makes no difference, i have tried that , my brother says same as Luddite so he is getting me a few resistors betwwen 400 - 600 ohm

12-01-2021, 12:12 PM	#1
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,909	Neutral switch issue i now have a nice LED dash with Tacho for my M750 every thing works fine except the neutral switch which stays on when in gear , the circuit is ok as is the switch , but it needs a resister as the switch is old and not giving correct resistance for LED on dash panel now , normal bulbs it works with , i dont want to spend £30 on a new switch ,, __________________ MONSTERMAN

12-01-2021, 12:29 PM	#2
pooh Lincolnshire Area Rep Join Date: Oct 2002 Location: Grimsby Bike: M900ie Posts: 471	Chances are you are switching the positive through the switch not the negative I had the same problem with my Koso dash. Which dash are you using? Pooh __________________ Slighty less brain cells than I was born with

12-01-2021, 07:32 PM	#5
pooh Lincolnshire Area Rep Join Date: Oct 2002 Location: Grimsby Bike: M900ie Posts: 471	Standard Monster neutral switch is single wire which makes a contact to earth when a gear is selected they work the same way as the oil switch it just supply’s an earth to the bulb or LED. Jerry I’m not sure what you mean the switch has the wrong resistance? It is an on-off switch there is no resistor except the one that would come within the dash to reduce the voltage from 12v to roughly 2v for the LED. Pooh __________________ Slighty less brain cells than I was born with Last edited by pooh; 12-01-2021 at 07:37 PM..

12-01-2021, 11:36 PM	#7
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,909	bike has one wire to neutral switch changing polarity on the Contagiri dash makes no difference, i have tried that , my brother says same as Luddite so he is getting me a few resistors betwwen 400 - 600 ohm __________________ MONSTERMAN

12-01-2021, 10:01 PM	#6
Luddite Registered User Join Date: Aug 2011 Location: Southampton Bike: M1100evo Posts: 2,465	If you want to calculate the value of the necessary resistor, you'll need to know the voltage and current of the LED you're using. Then you can use this calculation to determine which resistor you need. R = [V (Battery) ➖ V (LED)] ➗ I (LED) So, for a typical standard LED with a forward voltage of 2V and a current of 20mA, the necessary resistor would be: [12V ➖ 2V] ➗ 0.02mA = 500 Ohm An extra bright LED may have a forward voltage of around 3.2V so the required resistor for that would be: [12V ➖ 3.2V] ➗ 0.02mA = 440 Ohm The resistor should be wired in series and is not directional so it doesn't matter which way round you install it.