PAS not working

[Harllequin]

Good afternoon chaps.

After a good while of enjoying the bike I built for commuting what you guys helped me spec years ago I've run into a problem.

The throttle works fine but when I pedal it does not activate the hub motor any more.

My particular version of the S861 has the following menu :-
p01 Wheel size
p02 Magnet count
p03 Display backlight
p04 Miles or KM
p05 Voltage
p06 Off timer
p07 Max speed limit
p08 (not sure
p09 odometer reading / reset

Nothing in the setting has been change since the fault came about and I can't see anything in that menu that would prevent the PAS from activating.

Got out the multi-meter, my guess is: -
Black = ground
Red= supply
Green = signal

My red is showing 5.1v
The green is constantly showing 4.6v no mater if the crank is turning or not.

I've got no error messages on the screen.

Any advice on trouble shooting would be most welcome please.

Thank you kindly in advance.

​

 

[E-HP]

What type of sensor are you using (single piece, two piece with disc and sensor, etc.)? If it's two piece, you may want to check the gap between the sensor and the magnetic disc.

 

[Harllequin]

What type of sensor are you using (single piece, two piece with disc and sensor, etc.)? If it's two piece, you may want to check the gap between the sensor and the magnetic disc.

It's a 2 piece one, 5 magnets on a disk, sensor on a bracket. I've tried it as far away as it will go and as close as I can get it.
The voltage at the plug end does no change at all.

 

[E-HP]

It's a 2 piece one, 5 magnets on a disk, sensor on a bracket. I've tried it as far away as it will go and as close as I can get it.
The voltage at the plug end does no change at all.

Sounds like the sensor is no longer working. Has is gotten wet?

 

[amberwolf]

The throttle works fine but when I pedal it does not activate the hub motor any more.

What happened to the bike before the problem occured?

If nothing happened to it, then what was changed on it?

If neither is the case, then you might check the magnet spacing to the sensor--too close or too far and they may not work. If changing the spacing doesn't change it, then the sensor has probably failed, and would need to be replaced.

 

[Harllequin]

Thanks for all the replies.

Alas nothing changed or happened that would make it fail, never used in the wet and no physical trauma. Bike is kept in the garage at home and a store room at work when used.

Is there a way to test the sensor or it's output using a multimeter?

I'll order up a new sensor anyway.

 

[amberwolf]

You've already tested it, according to the first post, and the output is not changing, staying at the non-activated voltage. The only test you can really do that's different is to use a different magnet to just manually swipe past the sensor, but it's unlikely that the magnets would ahve gone bad.

Most of these sensors drop to near 0V whenever the magnet passes them. Some of them latch and switch off (~5v) only when the next magnet passes (like the sensors in a typical ebike motor), some fo them only pulse on (~0v) as the magnet passes, and are off the rest of the time.

 

[Harllequin]

You've already tested it, according to the first post, and the output is not changing, staying at the non-activated voltage. The only test you can really do that's different is to use a different magnet to just manually swipe past the sensor, but it's unlikely that the magnets would ahve gone bad.

Most of these sensors drop to near 0V whenever the magnet passes them. Some of them latch and switch off (~5v) only when the next magnet passes (like the sensors in a typical ebike motor), some fo them only pulse on (~0v) as the magnet passes, and are off the rest of the time.

That's exactly the info I wanted to know. Thanks amberwolf.

New sensor came today, fitted than and PAS is back working again as it should be. Sensor was only £5 from amazon so I'm rather pleased

Thank you all very much again for the help.