Bad hall sensor and throttle voltages

Well I pulled out the 7805 and ran 5v through it (data sheet says up to 30v is ok) and it’s producing 2.6v. Then when I ran 3.3v through it it’s producing 1.1v. So it seems like this thing is dead.
 
fechter said:
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.
Click to expand...

Yes there is an 8 pin A42S BBHQ. I did try to find a data sheet to no avail. I’d mention that 5v output of the 7805 goes to a resistor and to that chip it seems. So maybe bad 7805 killed that.

Also that 8 pin goes into the 5v regulator input.
 
So can I give it some external 5v from a power supply in place of the 7805?
 
My throttle hall sensor works fine when I put 5 volts through it. I can’t get the controller to work even if I give it 5 volts. So I think I just shall replace the controller. Bummer.
 
frock YES!!!!! I had the 5 volt on the wrong way, because the outline on the board showed it reversed. Never have I had my foot run over by a bike and been this happy about it! Just need a new 7805 and I’m good to go! THANK YOU SO MUCH fetcher and amberwolf!!!
 
So I bought these but seems like theyre the wrong tool for the job. https://www.mouser.com/datasheet/2/389/l78-974043.pdf

Absolute max is 35v first of all, which is lower than my battery. Secondly when I plug it into my breadboard with 5v input it gets too hot to touch after a few seconds. WTF?
 
Normally the input would be getting around 12v from another regulator on the board. Without the 7805 installed, you should be able to measure this when the power is on. If you see pack voltage, then you have more problems upstream.
 
The issue was that I reversed polarity to the 7805. Anyways, i realized while trying to solve the heat issue that the 7805 is extremely inefficient. I require about a 30v drop from 35v to 5v at 300mA for hall sensors, which is 9 watts of lost power to heat. So wow, what a waste!
 
300mA is way more than the hall sensors should take. Most controllers use under 100mA on the 5v line. That's still a lot of wasted heat though. The newer designs are all using switching regulators that generate much less heat. If you have room, you can get one of those cheap adjustable regulator boards. I have used several of them with good results. Just run wires to the holes on the board.

Here's an example: https://www.ebay.com/itm/Lot-LM2596...6a:m:mMUcf6zQR3TVD_mc4aOddZA&var=660869636683
 
fechter said:
300mA is way more than the hall sensors should take. Most controllers use under 100mA on the 5v line. That's still a lot of wasted heat though. The newer designs are all using switching regulators that generate much less heat. If you have room, you can get one of those cheap adjustable regulator boards. I have used several of them with good results. Just run wires to the holes on the board.

Here's an example: https://www.ebay.com/itm/Lot-LM2596...6a:m:mMUcf6zQR3TVD_mc4aOddZA&var=660869636683
Click to expand...

Yeah, I bought one of those. I should have room. For now I’m utilizing the switching step up converter on a USB battery pack.
 
fechter said:
300mA is way more than the hall sensors should take. Most controllers use under 100mA on the 5v line. That's still a lot of wasted heat though. The newer designs are all using switching regulators that generate much less heat. If you have room, you can get one of those cheap adjustable regulator boards. I have used several of them with good results. Just run wires to the holes on the board.

Here's an example: https://www.ebay.com/itm/Lot-LM2596...6a:m:mMUcf6zQR3TVD_mc4aOddZA&var=660869636683
Click to expand...

Bought that thing, waited, then blew it up. The marking on the PCB for the 7805 is actually reversed, so I keep getting confused. On the lm2596 that design is actually insulated, but I think it’s fine to connect the negatives to each other. Now I bought one of these: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F272675267612. Looks promising!
 
fechter said:
300mA is way more than the hall sensors should take. Most controllers use under 100mA on the 5v line. That's still a lot of wasted heat though. The newer designs are all using switching regulators that generate much less heat. If you have room, you can get one of those cheap adjustable regulator boards. I have used several of them with good results. Just run wires to the holes on the board.

Here's an example: https://www.ebay.com/itm/Lot-LM2596...6a:m:mMUcf6zQR3TVD_mc4aOddZA&var=660869636683
Click to expand...
Oh, the 300mA number was wrong. That was the total 12v supply current. The 12v supply is created using a parallel 160 ohm resistor package which drops 26v at .325mA. The resistor package is really inefficient from my calculations and from my finger actually touching it. I measured it and it’s reaching 160C outside the case. Not good, I’ll have to put in a buck converter I think.
 
Hi Guys,
Im having a very similar issue atm but it is only in the low voltage state when throttle is plugged into controller. This is on a 3000w brushless motor

https://www.qsmotor.com/product/3000w-mid-drive-motor/

if nothing plugged into controller then 5v shows normal but as soon as plug into it reduces to 2,7-3v range and get nothing on signal wire.
Testing throttle separately just hooked to 5v battery all seems to operate fine and I have also tested brand new throttle in its place.

Given that where should I be looking for the cause of such a fault. I haven't had controller open at all but im thinking it must be something in there.

Any help would be appreciated
 
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