Author Topic: Magic Pie 4 vector not working after ball bearing replacement  (Read 1839 times)

Offline Tawapah

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Magic Pie 4 vector not working after ball bearing replacement
« on: October 18, 2022, 07:02:06 PM »
I’ve been very happy using a front wheel Magic Pie 4 vector for about 8 years before it began to make a lot of noise. I quickly determined that it had to be the ball bearings. That was correct and therefore I got a new replacement.

After assembling everything again with the new ball bearing it didn’t want to turn anymore when throttling and only makes a light single "click" sound every time I turn the throttle up.

I opened the cover again to see if I would notice anything and sadly I maybe think it could be a damaged coil shorting. But since I’m no expert on the subject, I’m now writing here to hear your opinion on this. I have attached two photos showing 3 sections of the coil which I think could be shorting that looks like grey/white marks.

I should properly have disassembled/assembled it myself on my carpet floor at home instead of going to the local metal workshop of where it was handled on a metal table (which I believe could be the reason the coil was damaged, scraping on that table).

Can someone here help me clarify if the coil is too damaged and if its the reason it cannot run anymore?

I still hope there is a chance for a simple fix (maybe the Hall sensors), but since I saw the state of the coil I’m doubtful.

Offline Bikemad

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Re: Magic Pie 4 vector not working after ball bearing replacement
« Reply #1 on: October 19, 2022, 11:37:49 PM »
Hi Tawapah,

After carefully studying your photos, I don't think that the scraped insulation on those windings is severe enough to be causing a problem, as none of the exposed sections of the copper windings appear to be touching against other exposed sections.

I observed much worse physical damage to the armature windings on my vacuum cleaner motor after one of the bearings had completely failed:



The vacuum cleaner motor has been working perfectly since I carried out the repair at least two months ago. In addition to replacing both of the bearings, the windings had to be separated, soldered, painted (to insulate the exposed wires) and then super-glued to keep everything securely in place at high motor rpm.  :)

Assuming that the wheel still turns normally by hand, can you feel any noticeable resistance if you turn the wheel slowly and then gradually apply a small amount of throttle?
When the "click" occurs, does it affect the Battery Gauge LEDs on the throttle?

I suggest that you start by removing the controller from its housing to see if the LED on the back of the controller is producing an error code (regular number of flashes).
Also check that the Hall sensor connector is properly connected.  ;)

If the controller does not identify any faults you should see just a single flash when the controller is initially powered up and then nothing else.

If there is a problem with the Phase windings, I would expect to see seven regular flashes continually being repeated with an obvious pause in between.
A problem with the Hall sensors should produce five regular flashes. However, five flashes will also occur if the controller is powered up with the stator removed from within the motor's magnet ring.

If you do not see any error codes, you can turn Off the battery power and then disconnect the three Phase wires from the back of the controller (making a note of the positions of the Yellow, Green and Blue wires before disconnecting them).
With the three Phase wires disconnected, use a multimeter to measure the resistance between each pair of Phase wires (Yellow and Blue, Blue and Green and Green and Yellow) to see if there is any noticeable difference in the three readings.

Also use a multimeter to check for continuity (very low resistance) between the Phase wires and the metal part of the stator to determine if any of the windings are shorting against the metal.
The Phase windings should be electrically insulated from the metal stator assembly that they are wound around, so you should not be able to measure any continuity between the windings and the metal parts of the stator.

Unfortunately, it is difficult to know what might be causing the problem without knowing exactly what was done during the bearing replacement at the local metal shop.
If the controller was removed, perhaps the Phase wires could have been inadvertently mixed up when they were refitted.  :-\

Hopefully, removing the controller will enable an error code to be seen or perhaps an obvious problem will be noticed with the wiring inside the controller housing.



Alan
 

Offline Tawapah

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Re: Magic Pie 4 vector not working after ball bearing replacement
« Reply #2 on: October 22, 2022, 01:10:59 PM »
I'm relieved to hear that you think its not a coil shortage.

If I turn the wheel and gradually apply a small amount of throttle it doesn’t seem to make any difference in the resistance. But I can’t remember how smooth it was turning before the ball bearing replacement? Without any power I can slightly feel a tiny magnetic bump at every magnet it is turning over, but it can still turn around with ease and does spin around by it self for multiple cycles, if I push it around with my hand and then let go.

On a full battery the LED on the handle stays full (in the green light) while turning the handle applying the throttle.

When the cases was disassembled (both sides was removed) the controller was never opened so I was wondering if there is other means of measuring without opening its waterproof seal?

Would you still suggest opening the controller even that it hasn't been opened before, so that the error code can be checked?
« Last Edit: January 04, 2023, 05:06:56 PM by Tawapah »