...The never ended story of my Smiths speedo

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I once installed my pick up with a little too much air gap between it and the wheel mounted magnet. The speedo needle don’t move. Closed the gap a little, speedo perfect!

Like Ralph, I have the Puca units. The wiring is amazingly complex and I hate fitting them (I’ve fitted two sets now) but each time, they’ve worked fine (air gap issue notwithstanding).

Due to the complexity of the wiring, it’s easy to go down rabbit holes, and get stressed out, and go down deeper rabbit holes!

I’d leave it for a little while Yves and try and come back to it in a few days with a fresh head.
 
To day I receive the 3 wires sensor made by Caerbont, the one with the led light in the pick-up, I put the sensor on the bike, the led light everytime one of the four disk bolts pass in front of the sensor.
But the pointer is still dead....
My parts provider Frank give me another Speedo, same one, I will try this one tomorow
Keep you posted
Yves
 
Fast Eddie said:
I once installed my pick up with a little too much air gap between it and the wheel mounted magnet. The speedo needle don’t move. Closed the gap a little, speedo perfect!

Like Ralph, I have the Puca units. The wiring is amazingly complex and I hate fitting them (I’ve fitted two sets now) but each time, they’ve worked fine (air gap issue notwithstanding).

Due to the complexity of the wiring, it’s easy to go down rabbit holes, and get stressed out, and go down deeper rabbit holes!

I’d leave it for a little while Yves and try and come back to it in a few days with a fresh head.
Click to expand...
Hi Nigel,
My air gap is 1.5mm at the moment, but I try different gaps W/O sucsess.
You know me, only my broken hip can keep ma away from my workshop as I work more as 4 hours a day.
I wish to find someone with a fresh head, my head don't understand the situation anymore.
yves
 
Yves,
Is this how you have it wired? (minimum wires needed)

...The never ended story of my Smiths speedo
 
You could try the black wire from the sensor with the Red/Black wire from the speedo but if it still doesn't work it looks like the speedo is broken.

Also, I see the spec for the air gap for the sensor is 1mm to 2mm so at 1.5 that is good, which is proved by the light flashing anyway, I think you can be sure that bit is OK.
 
storm42 said:
You could try the black wire from the sensor with the Red/Black wire from the speedo but if it still doesn't work it looks like the speedo is broken.

Also, I see the spec for the air gap for the sensor is 1mm to 2mm so at 1.5 that is good, which is proved by the light flashing anyway, I think you can be sure that bit is OK.
Click to expand...
Thanks Storm, I will try the red/black tomorow, if not working, I put the new speedo
Yves
 
storm42 said:
You could try the black wire from the sensor with the Red/Black wire from the speedo but if it still doesn't work it looks like the speedo is broken.

Also, I see the spec for the air gap for the sensor is 1mm to 2mm so at 1.5 that is good, which is proved by the light flashing anyway, I think you can be sure that bit is OK.
Click to expand...
To day I try the Black Wire from the sensor to the Red/Black from the speedo, notings happens...
I put the other speedo that I receive from Frank, make the connections, try Red/blue and Red/Black, notings happens...

Remember: my speedo is the one with the green dot, usualy for Commandos, and Commandos are positive ground but the Sunburst is negatieve ground???
When I was buying the speedo, no instruction in the box, I mail the part # on the box to Peter at Caerbont and he send me instruction for negative ground. I belief now that the speedo with the green dot is for posietive ground only.
Your opinion please
Yves
 
I see Vercu has a negative earth Norton and a working speedometer, but hasn't said if it is a Norton specific one. You may be right about the Norton green dot being positive earth and I cannot find a specific diagram for the Norton clock, all the wiring diagrams I can find state the clocks are negative earth only.

To speed things up I could ring Caerbont tomorrow for you and find out if this is the case.
 
Just a thought, did you lower the PPU from the factory default on the new speedo for the test? mine didn't work until I set it to 800
 
storm42 said:
I see Vercu has a negative earth Norton and a working speedometer, but hasn't said if it is a Norton specific one. You may be right about the Norton green dot being positive earth and I cannot find a specific diagram for the Norton clock, all the wiring diagrams I can find state the clocks are negative earth only.

To speed things up I could ring Caerbont tomorrow for you and find out if this is the case.
Click to expand...
If you can be so kind to ring Caerbont please,
thanks
Yves
 
Unless the body of the speedo and/or the sensor are earthed then there is no need for -ve or +ve versions.
 
kommando said:
Unless the body of the speedo and/or the sensor are earthed then there is no need for -ve or +ve versions.
Click to expand...

I have a feeling they will work on either + or - earth, whilst there isn't much info on the speedo out there, the rev counters will work just by swapping the wires over according to the available diagrams. Having said that nearly all the available speedometer diagrams state negative earth only.

Yves, I have rung them and got though to a lady who told me they are closed on Fridays, she did try to put me through to somebodies home number but they didn't answer. She was as helpful as she could be, but no banana!!

She asked me to ring back on Monday which I will do.

I did think that it looks like it should work on negative earth because you said you are getting the startup sweep of the pointer.

Could Vercu confirm his is working on Negative or positive earth?
 
storm42 said:
I have a feeling they will work on either + or - earth, whilst there isn't much info on the speedo out there, the rev counters will work just by swapping the wires over according to the available diagrams. Having said that nearly all the available speedometer diagrams state negative earth only.

Yves, I have rung them and got though to a lady who told me they are closed on Fridays, she did try to put me through to somebodies home number but they didn't answer. She was as helpful as she could be, but no banana!!

She asked me to ring back on Monday which I will do.

I did think that it looks like it should work on negative earth because you said you are getting the startup sweep of the pointer.

Could Vercu confirm his is working on Negative or positive earth?
Click to expand...
Thanks Ralph,
I try 800 this morning, no changes...
I reduce the gap to less than 1mm, no changes...
Yves
 
My Norton P11 is converted to negative earth.
For information: the ppu (km) number is set to 5792 for 2 magnets and an 18 inch rear wheel.
Yves: just a tought: did you check the signal from the sensor with a multimeter? When turning the wheel by hand the resistance should switch between zero and full with the reed sensor. Sorry if that is too simple :)
 
vercu said:
My Norton P11 is converted to negative earth.
For information: the ppu (km) number is set to 5792 for 2 magnets and an 18 inch rear wheel.
Yves: just a tought: did you check the signal from the sensor with a multimeter? When turning the wheel by hand the resistance should switch between zero and full with the reed sensor. Sorry if that is too simple :)
Click to expand...
I will do that tomrow
Thanks
Yves
 
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