- Joined
- Aug 7, 2021
- Messages
- 52

I have a Smiths Electronic speedo on my Combat, it was running fine with the standard speedo drive and smiths speed sensor until the speedo drive died. So I thought I would splash out for one of Matt's CNW sensor units. This replaces the rear wheel speedo drive with a stainless fitting which has six raised buttons to trigger a sensor mounted on the supplied wheel spacer. This worked fine (for a while), but I have had two sensors fail, one lasting several weeks and one failing during the first ride after fitting. The sensor itself is powered with 12v , +ve to a wire connected to the battery and -ve to the ignition switch. The sensor is from Dakota digital in the USA and is quite expensive, Matt very kindly sent a replacement sensor after the first failed, and I ordered a new one when that failed. Matt seems to think that they are usually very reliable, and that the problem probably lies with my electrical system.
I think it must be voltage spikes killing the sensor, I currently have brand new A-Reg one reg/rectifier installed, and no capacitor. I am not using any resistor plugs/leads or caps on the ignition.
Would un suppressed ignition cause sufficient voltage spikes? If so would Champion RN7Y plugs be a better bet than the N7YC currently fitted?
Would it be worth fitting a zenner diode across the +ve and -ve feed to the sensor.
To be honest I'm a bit out of my depth, any advice would be gratefully received.
Thanks
Tom
I think it must be voltage spikes killing the sensor, I currently have brand new A-Reg one reg/rectifier installed, and no capacitor. I am not using any resistor plugs/leads or caps on the ignition.
Would un suppressed ignition cause sufficient voltage spikes? If so would Champion RN7Y plugs be a better bet than the N7YC currently fitted?
Would it be worth fitting a zenner diode across the +ve and -ve feed to the sensor.
To be honest I'm a bit out of my depth, any advice would be gratefully received.
Thanks
Tom