Unity with master side bad detection

Hello everybody,
Im giving this a new thread because i feel like its getting flowed over in the noob questions thread.

The situation is as follows:

I have a repaired unity, the side that is repaired gives a consistently bad reading in the form of a too high resistance. It spins fine when doing detection but after it just starts sputtering and being inconsistent.

First post

Boys i need your help.

One side of my unity is detecting weird resistances in the motors. I used the newest VESC firmware (5.2) didnt use unity tool since i have a uart remote (vx1)

I switched the motors and these were the results.


Motor 1 detection

Motor 2 detection

It seems like it reads 50 mili-Ohms too high

(This is detection before and after motor switch)
I have the unity mounted on a heatsink.

It detects normally but when i try spinning the motor to check directions it starts cogging a lot. Broken unity? Broken firmware?

Incompatible firmware maybe?

Follow up post

I did reflow all the connections so there is no way thats the issue. Its a pre blood unity btw
@Deodand @MartinSp @seaborder @linsus

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I am about to test it with two racerstar 5045 motors to see how it detects these.

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if the other side works, driver and logic should be fine.

check all that points, the bridge looks a bit squisy, when the unity works again give it some epoxy there.

check the fets

Is there a bridge or just solder on the shunt? Also check for solderballs

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The other side is good i think. I will check, thanks!

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image

Is that a patch? So whats actually broken here? The antispark? Cause I’m guessing the red wire bypasses it entirely?

Check all voltages, VBAT->5V->3.3V that they’re fine.
Check resistance in each half bridge of mosfets.
Clean that gnarly looking PCB. Defluxer or isopropanol should do the trick

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I have no idea what broke actually but i guess not the antispark, that one still works.

Ill clean the pcb too :rofl: i had to get it off my heatsink which was a pain in the ass.

Cleaned the pcb for you @linsus

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These are the results with the 5045 200kv racerstars, as you can see, again 50 mili-ohms too much resistance.

Again, same problem. (Excuse me for the jank setup)
@MartinSp could it be you wired it to the wrong resistor?

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i had one like this. it was the first one i got from the raptor clearance shop.

i was told there is an known production issue that sometimes causes this.
and used to be caught when supposedly they actually had QA…

i don;t think you are going to be able to run 2 motors on this…

i still have mine laying around and plan on running a single motors off one side… not entirely sure i can do that.

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here is the link on my previous discussion

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here is the issue @Deodand had mentioned.

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I think the three half bridges got repaired, those must be these right?

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Thanks for the info @rafaelinmissouri very interesting informatiom you have provided!

Btw i am no guru whatsoever so i have no idea what values to check etc.

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Sorry but that is beyond me.

and regarding the values. what i used as a reference was the recommended motor amps. and expected them to be within 5 amps or so.

so mine were way different regardless of which motors i tried.

This jumper wire just connects V+ to V+… it really shouldn’t do anything and can likely be removed. No idea why that would be there, there is a big V+ power plane of copper connecting these.

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How weird, do you think the 3 repaired half bridged need to be redone?

Thanks for your help to mister!

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Half bride is one leg of the Mosfets that controls a phase. Not sure what you’re refering to. I asked you the check the mosfets just to see if they’re whole, resistance should be in the ballpark similiar to the other side of the unity f.e

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Ok will check, sorry, like i said im pretty bad with this stuff.

3 Likes

No problem, if we’re speaking greek just point out what is unclear to you

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Would you mind pointing me to the fets and what points to measure? All the components are unmarked as in there are no serial numbers etc on them.