Can anyone identify this PAS component (Pedal Assist Sensor)

[liared]

I have promised a friend of mine to ask for help in this forum to identify a broken PAS (Pedal assist system) component on his e-bike. My friend bought a Chinese, no brand name, e-bike a few years ago but the seller is nowadays unfortunately out of business.
The e-bike looks like this:

We need a new identical no broken PAS sensor with cables attached (4 Cables entering the PAS sensor).

We have not been able to find a replacement sensor on the Internet.
Does anyone on the forum know about this type of PAS sensor and where to get it????[*]

 

[mlt34]

Well that's odd, a four-wire PAS sensor? The standard is 3 wires, just like a throttle. looks like that's something other than the standard hall effect sensor. Perhaps it can be replaced with either a standard hall sensor PAS sensor or a hand throttle. The controllers that come with those ebikes almost always have a connector for a hand throttle but leave it unused due to european legislation. I've upgraded tons of those style ebikes to have a hand throttle for people who found it annoying to have to mime-pedal just to make the motor spin...

 

[jateureka]

That looks more like an early style 'torque sensor' that mounts in the crank/chainring. The one I saw had the chain ring mounted to the crank via a rubber mount and hall sensors detected movement of the chain ring as a result of force applied.

I'm not sure you can buy the sensor seperately or if you have to replace the crank assembly as a whole unit.

 

[teklektik]

That's not a torque sensor, it's a simple PAS wheel pedaling detector - you can see the two magnets on the chainring and the two hall sensors embedded in the goop.

Many PAS detectors have two hall sensors and a bit of logic so that the pulses are gated off when pedaling backwards. There are three leads: (Power, Gnd, Pulse). Here it appears that since this is an integrated unit, they omitted the logic and are simply sending the output of the two halls directly to the controller (Blue and Green leads).

You can see the offset in the magnets - this causes the two hall pulse waveforms to be slightly overlapping but out of phase so the controller can determine direction.

I'm pretty sure that there is nothing in the sensor unit except the halls (possibly a couple of resistors, but I doubt it). A skilled DIY techie should be able to clear the potting silicone and re-attach the wires. If the halls themselves are damaged, they should be pretty easy to replace - either reading the part number or finding similar bipolar hall sensors with the same packaging configuration so the magnet motion will cause them to trigger (i.e. it looks like the familiar SS40/SS41 package will not be aligned properly for those magnets...). The odd shape of the detector that fits into the punched sheet metal over the magnets makes me think this is a unique little part made by that particular bike manufacturer.

What worries me is the clean stripped ends of the wires - why? If the leads have shorted, the controller may be zapped.
>> Does the PAS screen still light up?
>> Do the throttle and/or other display/button features still work?
If not, the unit is likely Kaputsky. If things are working, it may be fixable.

If this is outside the skill set of you or your friends, you might bring it by a local Tech School and see if one of the electronics instructors will assist in getting it repaired.

 

[mlt34]

Good idea on the local tech school.

If say, one of the sensors is blown or the leads are sheared off too close to make it fixable, do you think he could get by with just reconnecting one hall sensor? It depends on that controller and I'm not familiar with any controllers that use two sensors for PAS.

 

[d8veh]

Pas sensors are really cheap to buy, and small controllers are quite cheap too. If it were my bike, I'd chuck the controller and PAS sensor, and get a modern one with throttle and LCD with 5 levels of PAS. This assumes that it's a three phase motor (brushless) not a brushed one.

 

[teklektik]

Good idea on the local tech school.

If say, one of the sensors is blown or the leads are sheared off too close to make it fixable, do you think he could get by with just reconnecting one hall sensor? It depends on that controller and I'm not familiar with any controllers that use two sensors for PAS.

Yep - but it would lose the ability to detect backward pedaling.

The direction detection works by looking at the level of the second sensor on the rising (or falling) edge of the first (the blue and yellow wires in this case). In one direction the level will be high and in the other the level will be low.


So, to make this work with only one sensor, you need to determine whether to hook up the blue or yellow to the 'good' sensor, then determine if the other wire should be tied high or low to always appear to be going in the proper direction.

However, a little looking on Mouser or equivalent should turn up a usable part for a few bucks - a techie should be able to handle that.

On the other hand, I'm thinking that d8veh's recommendation to replace the electronics in toto may turn out to be the most doable with the available skill set...

 

[mlt34]

d8veh's recommendation to replace the electronics in toto may turn out to be the most doable with the available skill set...

probably the most beneficial too. He can add a throttle and be done with the dinky PAS for good.

 

[teklektik]

Yep - my thoughts as well... perhaps start another thread for specific recommendations for a replacement - needs photos of bike crankset and motor.

liared-
Another thing to try would be to bring the sensor to a computer repair shop (instead of the whole bike) and just have them tack on some labeled or colored hookup wire for you. Print this thread and bring it along. They will probably charge you $40 for the exercise for a no-guarantee 'repair'. You could then splice up the leads yourself. Not the best idea, but just throwing stuff out there...

 

[liared]

Assuming the no brand name motor can´t be identified by written name/identification on its surface:
Is the a way to deternine if the motor is ”brusless” without opening up the motor??

 

[mlt34]

Assuming the no brand name motor can´t be identified by written name/identification on its surface:
Is the a way to deternine if the motor is ”brusless” without opening up the motor??

Can you check how many wire leads exit the motor? Try checking where the wire from the motor meets the controller. You may have to open up a screwed on panel near the front of the battery. You don't need to unplug any of those wires, just count them.
Two wires means brushed
Three wires means brushless and sensorless
Eight wires (three thick and five thin) means brushless and sensored

 

[katatonic]

the 4 wire pas sensors have 2 signal outputs ,they are able to do directional sensing ,for example with cycle analyst you could set it to regen say if you pedaled backwards ,theres a good section on it in the cycle analyst manual on different ways you can use it