replacing dead hall in a MAC

nonlineartom

nonlineartom

1 kW
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Bradford, UK
I've got this 6T mac with a suspected dead hall. I've got the side case off and I can see the halls are mounted onto a PCB and the hall sensors themselves are epoxyed into the gaps in the stator. I've got a replacement whole PCB on order compelte with halls soldered in so now all that remains is get the old ones out of there. Whats the best method for getting that epoxy bond loosened off whilst causing as little damage as posible to the motor itself?

Dremel?

Freeze it?

Heat it?

answers on the back of a postcard
 
The easiest way is to take the stator out, then the hall can be easily knocked out with a screwdriver. If working from the front of the stator only without removing it from the yoke, it is very tricky to get the hall sensor out IMO (if anyone has a good way to do this without removing the stator, please let me know), you may end up damaging the winding in some way. I need to do a procedure for just this, so if you can hang on, I will get something written up with some pics in the next week or so.
 
cell_man - an official superhero, thanks for that, if you could send me a paypal invoice for the new halls and gears that would also be useful

Ta
 
cell_man - an official superhero, thanks for that, if you could send me a paypal invoice for the new halls and gears that would also be useful

Ta
 
Obviously the best way is as Paul says. That does however involve removing the phase and hall wires etc, unscrewing the aluminium (or aloominum if you're stateside)stator mounting plate, lifting that plate up which reveals the big circlip that retains the stator to the yoke (the spinning magnet part). Remove that circlip then put the aluminium mount back on. Hold the yoke and carefully bang the gear side of the axle on a firm wooden surface or similar, this will get the stator out of the yoke- it has magnetic force and bearing interference fit to overcome. You might be able to do this without disconnecting the phase and hall wires but I can't tell you as I disconnected mine at the outset.

Edit: I reviewed my repair thread and these are the instructions from Paul:
You'll have to remove the stator to do the hall sensors I'm afraid, take care. The yoke is secured to the stator support by a large circlip located under the aluminium shaft support in the centre of the stator. You need to remove the other circlips fitted on the axle too, it's all fairly obvious once you've removed the shaft support. What I have done in the past is fit the shaft support back onto the stator support and then knocked the shaft down onto a hard surface, knocking the stator out of the yoke. Use proper working gloves when messing with a motor, they snap back together very strong and you could easily get a nasty pinch or a lot worse.... If you use this method, you should use longer bolts in the shaft support (6pcs of M4 if I remember correctly). The standard bolts securing the shaft support to the stator support are a bit short and the thread in the aluminium stator support can be stripped. Another option is to rig something that will hook under the stator so you aren't relying on the stator support.
Click to expand...



With the stator out you can then access the halls alot easier.

I found that you can soften the epoxy holding the halls in with either careful use of a heat gun or a micro butane torch. Whilst the epoxy is hot, it will get soft and can be scraped off with a small screwdriver. The epoxy on top of the halls pcb will just about peel of whole.

I guess you could do this with the stator in situ- you would nee to get the epoxy off the pcb, desolder the halls, remove the board then you'll be able to get at the faulty hall.

I assume you have thoroughly checked to make sure it's the hall and not the wiring?
 
I bought the motor faulty, presumed dead hall but now you mention it, it could just be wiring, the wires all look to still be connected, no visible damage, Providing I can access the legs of the halls and they arn't covered in epoxy is there a way to check the functionality of the halls with a multimeter. The wires from the motor use the same yellow 16AWG wire for the halls and phase wires so there is no way to tell what is what at the connector end.
 
If you got the motor dead, do some simple checks first.

Mount the motor with the axle vertical in a vice so the yoke can be spun by hand. Note how much resistance there is. Now progressively connect together the phase wires to each other. Each time a pair of phases are connected, spinning the yoke should become much harder. If there is little difference then you have a problem with the phase connections or windings.

Your wiring sounds funky. There should be three phase wires 16g sounds about right. Then you should have five very small guage wires for the halls- red, black, blue, yellow and green. Maybe chuck some photos up for us to confirm? If you have a look at my MAC repair thread you can see what they are supposed to look like. http://endless-sphere.com/forums/viewtopic.php?f=2&t=34806

Testing the halls without an ebike tester is tricky- standard digital multimeters tend not to react in time to measure the hall outputs. A decent old analogue meter should work- put 5-12V DC on the red(+) and black (-), measure between the black and then the yellow, blue and green wires and slowly rotate the yoke. You should see the meter needle moving to indicate the hall switching.
 
I had a hall go on mine after about 10 mins use :(

u can test the sensors with a digital multimeter by powering up the controller, then testing the voltage from each sensor as you turn the wheel, they should all jump from 0 to 5v.

I ended up digging out the faulty hall sensor with the stator in place and fitting a new one, cellman said he was going to send me a new board but never did, along with a discount on my next order but he never replied to any emails so I gave up :)
 
Sorry to dig up a older thread , but looking for some info and have not found it yet.

I had one of my halls go bad in a 8t mac I have setup as a mid drive in my yuba. I have a board with halls
coming to me , but was curious if I could just put in new halls to the motor without using the board ?

Is that board required for the mac motors or is it just there to make it easier to replace if needed ?

Thanks in advance going to read this other thread hoping maybe it's answered there.
 
i would bet it is a broken trace or bad solder joint rather than a bad hall sensor. usually they only fail when shorted to the phase wires on twistoff. otherwise look for bad connections.
 
Last night I took apart the mac dug out the old halls and even painted my windings.

My tester showed a bad hall , but yea once I got the wires out there was cut , but it wasnt obvious to be my issue.

Anyway I have to replace the halls regardless now and I have spare ones from lyen - just wondering if I can bypass
the board on these motors or if it only works with them ?
 
ohzee said:
just wondering if I can bypass the board on these motors or if it only works with them ?
Click to expand...

sure. y not? no need for that pcb (other than easier and cleaner installation). just make sure not to forget the little cap! the location of the halls is given by the gaps between the windings. then just connect the hall sensors to the power, ground and corespondent hall wire and you're done.
 
izeman said:
ohzee said:
just wondering if I can bypass the board on these motors or if it only works with them ?
Click to expand...

sure. y not? no need for that pcb (other than easier and cleaner installation). just make sure not to forget the little cap! the location of the halls is given by the gaps between the windings. then just connect the hall sensors to the power, ground and corespondent hall wire and you're done.
Click to expand...

thanks - I have it about all wired , but it looks like the "little cap" goes between the red/black hall wires.

Anyone know why and what it does ? Figured Id wire it in , just do not understand what it does thanks.
 
ohzee said:
Last night I took apart the mac dug out the old halls and even painted my windings.

My tester showed a bad hall , but yea once I got the wires out there was cut , but it wasnt obvious to be my issue.

Anyway I have to replace the halls regardless now and I have spare ones from lyen - just wondering if I can bypass
the board on these motors or if it only works with them ?
Click to expand...


I'm going to be replacing my dead hall(s) this weekend, mine look pretty well epoxied in there, how did you pry yours out without damaging the motor? any tips?
 
there were several tips already, heat and using a small pick is essential imo.

i doubt if your hall sensors are dead, usually it is just a bad connection. you should know which hall sensor is bad from testing so you only have to look for the broken lead on that one sensor. did you test it first before opening the motor to see which one is bad?
 
I bought the motor as faulty, it starts up and spins in some positions but if the motor stops in the wrong place it won't start up which suggests a dead hall. I don't have a motor tester and I'm not sure how to test with a multimeter. I took a close look and all the wires seem to be in good condition. Good contact to the PCB. Can't tell if the legs of the hall sensors are ok because they are hidden behind the PCB
 
errr no. blown fets doesn't produce that effect. I've had the same fault caused by a hall wire not being fully plugged in, so I'm 95% certain it's a either a hall or the hall connector. A broken phase connection produces a grunty torque-less drive, this just won't start spinning in some positions.
 
It's doable if you are very careful and pay attention to where the windings are.

Also important is don't remove all the epoxy just enough to fit the new halls in there.

heat gun & soldering iron help brittle it up.

So the mac hall board has a little round cap with 104 on it between the positive and negative any ideas ?

http://www.alibaba.com/product-gs/297540794/Ceramic_disc_Capacitor_104_50V_Y5P.html

that's what it looks like
 
the capacitor is placed on that little pcb board to smooth out the electrical noise that appears on the red wire, the 5v supply to the hall sensor integrated circuit. some motors do not have one, but some do. what's wrong with putting the same pcb board back in place when you replace the hall sensors?
 
dnmun said:
the capacitor is placed on that little pcb board to smooth out the electrical noise that appears on the red wire, the 5v supply to the hall sensor integrated circuit. some motors do not have one, but some do. what's wrong with putting the same pcb board back in place when you replace the hall sensors?
Click to expand...

That's what I needed to know thanks.

So the board I had must have like 1/4 inch epoxy on both sides so I had to dig down to get to the board where the halls had gone.
When I did hook it up after cleaning out the old holes I had one that did not make great contact and I could not fix it. So from there
I said screw that pcb board and here I am.

I have a new board in route to me with halls to use if needed so one way or another she will be going again.
 
Can someone briefly walk me through diagnosing the dead hall?

I've got the motor open on the bench, all connectors look good, nothing looks charred or burnt. Where do I stick the multimeter pins and on what mode to find out what's died on me ? what am I looking for ?
 
to diagnose which hall sensor is bad, you should do it while the motor is intact with the controller powered up and the 5 pin hall sensor plug connected. you don't need to connect the throttle or the phase wires just the hall sensor plug.

using your voltmeter, you measure the voltage on the pins inside the 5 pin plug while slowly rotating the wheel. the hall sensor voltages will toggle on and off. if one is bad, it will not toggle, it will remain fixed as the wheel rotates.

put your black voltmeter lead on the black wire in the 5 pin plug, and the red probe on the BGY hall wires inside the plug. easy peasy.
 
You sir, are a genius.

Now if only the previous owner hadn't entirely backfilled the connector with silicon.... eurgh.
 
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