Bad hall sensor and throttle voltages

420b

100 W
Joined
Aug 13, 2018
Messages
126
Hi. I’m trying to figure out why my ebike brushless hub motor won’t spin when I throttle. It seems like the voltages across hall sensors and the throttle are wrong.
The H+, W, V, U, GND pads are for the hall sensor. I get .77 volts to the H+ to ground. I get 1 volt on W, V, or U to ground, even when spinning wheel.

The SD, 4.3v, and GND pads on the left are throttle. There is .66 volts from 4.3v pad to GND. There is 0 volts from SD (which I assume is throttle sensor voltage) even when spinning the throttle.

I don’t know what is going on. I didn’t really do anything to the controller other than take it apart. Maybe something got destroyed by static? I need help!
 
Either the "ignition" or "keyswitch" wire from the main battery positive to the input of the low voltage power section is no longer connected, or soemthing has gone wrong in the LVPS. Most of them use a 7812 12v regulator powered off of some large resistors to the I/K wire, and then have a 7805 5v regulator powered off the 7812.

Both of those are usually little three-wire transistor types; sometimes the 7812 is shaped like the FETs are. If the writing is facing you that says 78xx, then the pin on the right is the output voltage, the middle is ground. So if there's not the right voltage at the 7805, check the 7812. If it's ok, then something is probably shorting the 7805 out; either a defective part (static, etc), or an actual wire-short. If theres no 12v either, then check the input to the 7812. If it has no input, then check the wire from the other side of the big resistor(s); it should have battery voltage. If it doesn't, you'l have to trace that out.
 
Thanks for the quick help! I’m going to try and do what you said, I just wonder why it died on me. All i did was take it apart to install wattmeter in line with power. I guess next time I need to ground myself and be careful.
 
It sounds like something on the 5v supply is shorted. You could try disconnecting the motor halls and the throttle and see if the 5v supply comes back.
If not, it’s unlikely you can fix it. You may need a new controller.
It won’t to take apart the controller and look for any signs of heat.
 
I have a wattmeter that’s reading 0 though. If there was a short should there be current?
 
If something on the 5v supply shorts, the voltage regulator should limit the current to a low value. You may not see it on a watt meter.

I've seen several controllers that blew the microprocessor, which pulled the 5v supply down to near zero. If you're lucky, either the motor halls or the throttle shorted, which are easier to fix. Shorted throttles are not that uncommon, especially if they get wet or the wires get mangled. Try unplugging the throttle and motor halls one at a time and see if there is any change.
 
The 78L05 (datasheets say it’s my 5v outputter) shows low voltage from ground to output (2.5v) and 1v from ground to input (is that too low?). Also, whenever I unplug all the cables, then the 78L05 and the pads where the throttle and hall wires go (pictured in OP) have no voltage, so I don’t know what I’m supposed to check when the cables are out.
 
As I said before, if there's low or no input to the 7805, then you ahve to check teh 7812 that will probably be somewehre between battery and the 7805 input.

Then if the 7812 doesn't have input, you have to check teh stuff between it and the battery.

My guess is that you aren't getting battery power to the 7812 because the ignition/keyswitch wire is not connected anyomre, somewhere along it's path.

The other possibility is that if you have a battery with a BMS, and it's drained down to shutoff point (LVC), it could put out just enough voltage to appear working with little or no load on it, but not actually be able to operate teh controller.

If there's no voltage in the controller at all whenever the motor hall wires and throttle sensor wire are disconnected from it, then that means all the voltage you do see is leakage thru one of those, and that there is probably no power at all to the controller from the battery, and/or it's keyswitch ignition wire is simply not connected.




As for pictures, I don't see any. If you attach them directly to the post in the attachments tab, then anyone that can see the post can see the pics.

You said in another post above that you took the controller apart to add a wattmeter...but you don't normally have to open a controller to do that. You just wire the wattmeter's shunt in series with the battery input to the controller.

(Some, like teh Cycle Analyst (CA) DP version, use the internal shunt of the controller instead of their own external one, so for those you do have to add some wires inside the controller. But you then also have to measure the actual shunt value of the controller, or the wattmeter readings will not be correct. Using an external shunt with a known exact value or one built into a wattmeter means it doesnt' have to be measured and calibrated.)
 
I can’t actually find a 12 v regulator. Maybe you can spot it. https://ibb.co/mZG1BU
I found a 78L05 which is my 5volt regulator, and I found a MPSA56 which is a bipolar transistor (don’t know what that does). There is no nothing else really sticking out (literally).
 
So I ran continuiety test between the throttle wires, and they all checked out to the connector from the board. Now I’ll take apart throttle and check.
 
420b said:
I can’t actually find a 12 v regulator. Maybe you can spot it.
I don't see a pic to spot anything in. There's a link but nothing comes up there except a script warning by my browser.

But it usually looks just like one of the FETs. Sometimes it is on the back of the board.

If you attach the picture to the post in the attachment tab, we might be able to see it.

I found a 78L05 which is my 5volt regulator, and I found a MPSA56 which is a bipolar transistor (don’t know what that does).
The transistor might be part of a switching supply to convert down from battery to lower voltage (rather than using the big resistors and 7812).

If you have at least one very large resistor on the board, near the big can capacitors where the battery wires come in, then usually the 7812 or other power supply is right there.


But it doesn't matter--if you can't find the 7812, simply measure all the places where you should have battery voltage in there. It should be at the big red battery wire, and at the (probably red) keyswitch / ignition wire (which will connect somewhere near the big resistor or other power supply.
 
Quite sorry to hear that the images aren’t showing up. I want to help you help me! Anyways, I tried uploading them to another site (I can’t get my images attached, they are larger than 512KB).







 
Here is a better picture of the board.


I circled all of the 6 throttle connections.
 
Anyways, power looks good, except that red top left wire is labeled as 4.3v but it only has .6v to negative.
 
Also I did short my battery recently, but I pulled out my probes fairly quickly and the battery seems to still be alive. That said, I have another battery that I’m using that has not been shorted and I’m testing on both.
 
Full battery voltage across yellow and brown. When you click button it sends full battery voltage on green and black, and removes the voltage from yellow and brown by flipping green and brown to positive. Next I should test hall sensor or what? I don’t think hall sensor is getting the right voltage, only .66
 
Ok so the throttle is fine, no short and all wires have continuity. Hall sensor doesn’t give an output because it’s input voltage is only .66v. So I’m back where I started, knowing nothing. I don’t know what’s causing low voltage. Would board pics help ID components?
 
amberwolf said:
420b said:
I can’t actually find a 12 v regulator. Maybe you can spot it.
I don't see a pic to spot anything in. There's a link but nothing comes up there except a script warning by my browser.

But it usually looks just like one of the FETs. Sometimes it is on the back of the board.

If you attach the picture to the post in the attachment tab, we might be able to see it.

I found a 78L05 which is my 5volt regulator, and I found a MPSA56 which is a bipolar transistor (don’t know what that does).
The transistor might be part of a switching supply to convert down from battery to lower voltage (rather than using the big resistors and 7812).

If you have at least one very large resistor on the board, near the big can capacitors where the battery wires come in, then usually the 7812 or other power supply is right there.


But it doesn't matter--if you can't find the 7812, simply measure all the places where you should have battery voltage in there. It should be at the big red battery wire, and at the (probably red) keyswitch / ignition wire (which will connect somewhere near the big resistor or other power supply.

Are the pictures showing up now? I wanted to upload them to a hosting site because attachments are limited quality.
 
420b said:
I can’t actually find a 12 v regulator. Maybe you can spot it. https://ibb.co/mZG1BU
I found a 78L05 which is my 5volt regulator, and I found a MPSA56 which is a bipolar transistor (don’t know what that does). There is no nothing else really sticking out (literally).

I didn't see a thru-hole regulator in your pics, so I figure the 78L05 is a SMT part. If you can replace a surface mount component at home, have at it. I
 
The 78L05 is visible in the picture.

You can try measuring the input and output (against battery negative). The input should be around 12v.

78L05-Voltage-Regulator-Pinout.jpg

With the motor and throttle disconnected, you can also measure the 5v spot on the board when powered up. Just to eliminate the motor and throttle as a cause.
 
fechter said:
The 78L05 is visible in the picture.

You can try measuring the input and output (against battery negative). The input should be around 12v.

78L05-Voltage-Regulator-Pinout.jpg

With the motor and throttle disconnected, you can also measure the 5v spot on the board when powered up. Just to eliminate the motor and throttle as a cause.
The 78L05 doesn’t have power when I’m not plugging in those things. When I plug in and turn on the ignition then it has 1 volts input 2.5v output
 
docw009 said:
420b said:
I can’t actually find a 12 v regulator. Maybe you can spot it. https://ibb.co/mZG1BU
I found a 78L05 which is my 5volt regulator, and I found a MPSA56 which is a bipolar transistor (don’t know what that does). There is no nothing else really sticking out (literally).

I didn't see a thru-hole regulator in your pics, so I figure the 78L05 is a SMT part. If you can replace a surface mount component at home, have at it. I

It’s by the capacitor and labeled on board as 78L05. It’s a through hole type. It’s getting 1 volt input and from the spec sheet there is nothing that says minimum, only max. So I guess I buy a new 5 volt regulator and controller should work.
 
Not looking forward to buying 7805 online, shipping takes forever unless I’m willing to pay 10x the components price for US shipping. I actually have a 5volt smd regulator from a breadboard power supply. My smd 5volt reg has 800ma max, should be good to power a few hall sensors!
 
If you only have 1v on the input, then the problem is most likely upstream. There is a 12v regulator that typically feeds the 78L05. I couldn't really see well in the pictures but check out the little 8 legged chip close to the 78L05 and see if you can read the number. Most of the newer controllers are using switching regulators for the 12v. Once we have a number, we can try to look it up and get a datasheet that shows which pin is doing what. Usually when those switcher chips go bad, they smoke. Possibly there's a part feeding that went bad or the inductor went open.
 
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