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electrical noise affecting acewell speedo
luke2152 - 23/7/17 at 12:48 PM

After some suggestions from the tech gurus.

Have set up acewell 6x56 on my bike - a turbo'd bandit 1200. I used the bikes original speed sensor which is a hall sensor reading a 4 tooth wheel attached to the front sprocket.

Bike sensor has 3 wires - power, earth, signal out. Acewell has 2 wires -Earth, signal in. Connected power to 12v source, both earth wires to each other, both signal wires to each other with 100 ohm resister inline (following a vague writeup I found online).

Speedo works perfectly 1/3 of the time.
Doesn't work at all 1/3 of the time.
Produces random flickering numbers 1/3 of the time even when bike is stationary idling.

I rechecked my connections and all good. I think the random numbers are noise coming from the wiring running close to the coils. Hard to avoid that on a bike without running them somewhere hot. Can I do anything to shield them? Also maybe earth both the earth wires to the frame instead of joined to each other? Could also run the 12v hall sensor input from somewhere well away from the coils so that only the signal wire was near the coils? Remove the resistor or change its value or put it between the signal and earth or power wires?


gremlin1234 - 23/7/17 at 03:47 PM

the sensors should use an explicit 'earth' all the way back to the ecu , as should any power feed to the sensor.

its best first to focus reducing the source of the noise, including resistive plugs or HT cables

a medium wave radio can help identify some of the sources of noise.



[Edited on 23/7/17 by gremlin1234]


mcramsay - 23/7/17 at 04:06 PM

I had this issue with my stack speedo, the thing would go haywire after around 10 mins of running, I was using a 3 wire Hall effect sensor and no matter what I did it made no difference, I sent the speedo back to be tested and they found nothing wrong, I then tracked it down to the facet low pressure Pump, if I electrically disconnected with the car running on jack stands the speedo stopped acting mental. I then tried running separate wiring on the other side of the car from the fuel pump wiring... no difference.

In the end I admitted defeat and that I was not smart enough to fix the problem and fitted a normal 2 wire reed switch and magnet pick up with some glued on magnets.... never had a problem since... I spent 3 weeks trying to fix a problem that was solved in an hour by binning off the Hall effect sensor!!


russbost - 23/7/17 at 06:14 PM

Do you know what the Suzuki Hall sensor is putting out? The Acewell needs a 2.5 to 5V square wave, there are frequency limitations, but that doesn't sound like the issue in this case, you shouldn't need the 100 ohm resistor unless the voltage is outside the above range, in which case I wouldn't be doing anything without speaking to Acewell first!


luke2152 - 23/7/17 at 08:25 PM

quote:
Originally posted by russbost
Do you know what the Suzuki Hall sensor is putting out? The Acewell needs a 2.5 to 5V square wave, there are frequency limitations, but that doesn't sound like the issue in this case, you shouldn't need the 100 ohm resistor unless the voltage is outside the above range, in which case I wouldn't be doing anything without speaking to Acewell first!


I read it puts out 5v but haven't tested it - I expect a multimeter would do no good measuring square wave and just average it out.
And as I say it works perfectly when it works. Haven't figured out the circumstances of it working/not makes no difference hot or cold. High rpm or low. I hadn't thought about noise from the fuel pump as thats probably the biggest draw in the electrical system.


russbost - 24/7/17 at 07:20 AM

You'd need an oscilloscope to check it accurately. What was the reason for the 100 ohm resistor & have you tried it without the resistor?


avagolen - 24/7/17 at 01:04 PM

You do not have to use an oscilloscope to check the signal.
If you connect the voltmeter to the wires and power everything up
But do not start the engine, i assume no kickstart, and put the bike in gear.
Slowly move the bike until the sensor is aligned with one of the trigger points.
You should now see the trigger voltage.