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Augus

Auto balance problem

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Hi mates,

I would like to ask you for advice on a problem with the KS-16S.
I have done 3500Km, and since 1 month I have a problem. The unicycle has lost capacity for self-balancing and I lean forward a lot when I accelerate, and also a lot back when I brake, so that driving is uncomfortable and dangerous. In closed turns it is even more exaggerated. I can not solve it with the calibration of the application.
In short, the unicycle is no longer a horizontal board as before, but it seems like a seesaw. I have the experienced player mode, and firmware 1.07.
Let's see if someone gives me some clue to solve it.

 

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16 minutes ago, Augus said:

Hi mates,

I would like to ask you for advice on a problem with the KS-16S.
I have done 3500Km, and since 1 month I have a problem. The unicycle has lost capacity for self-balancing and I lean forward a lot when I accelerate, and also a lot back when I brake, so that driving is uncomfortable and dangerous. In closed turns it is even more exaggerated. I can not solve it with the calibration of the application.
In short, the unicycle is no longer a horizontal board as before, but it seems like a seesaw. I have the experienced player mode, and firmware 1.07.
Let's see if someone gives me some clue to solve it.

 

Reminds me of my ks16c when one leg of the capacitor broke.

You could check the motherboard for this and/or look for a motherboard replacement.

Anyhow - you should not go on driving after such symptoms without solving the problem. If it is like in my abovementioned case it could blow the fuse anytime!

You have some local dealer to check this? Imo replacing the motherboard has good chances to "cure" this situation and should not cost a fortune - but no guarantee without really identifying the cause...

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Ok, I will disassemble the motherboard and inspect it. Thanks.

Edited by Augus

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Can you show me some picture of those capacitors, please?

Edited by Augus

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This is not a 16S control board, so the alignment and location of the capacitors may be different. But they are these large cylinders that have two legs each going to the control board:BF191695-B842-472A-A882-CB43F6140DE6.jpeg.e9a9c2507c97c5f9d3ed404bbf1b6aaa.jpeg

Edited by mrelwood
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22 minutes ago, Wild Child said:

Augus,

When inspecting the capacitors, you are looking to see if they are "blown". If they are blown, they will be bulging at the top (or may have popped open). A good capacitor is flat on top.

 

I did not hear (till now) from these capacitors getting "blown" - but anyhow a good idea to look for this, too. In the times of the first ks16b it was just broken legs (under an insulation - so not to be seen at first glance)

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I put the behavior at standstill of my KS-16S. It tilts from almost + 2º to -2º. I think it's too rocking.

 

Edited by Augus

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I have disassembled the KS-16S to inspect the motherboard, because for a long time there has been an exaggerated anteroposterior swing, it does not go like a horizontal table, as if it had a 'initiate mode' in the autobalance. I've been told that it could be a blown capacitor, but I see them well, and the only thing that catches my attention is a funky cable like a spring with a loose end. What do you think?.

DSC_0676_result.JPG

DSC_0681_result.JPG

DSC_0690_01_result.JPG

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Loose cables like that are usually antennas. Not sure what for though, as bluetooth antenna is the square wave shaped track on the small additional circuit board. Still, I don’t think it has been detached from anywhere.

What I would do is check the large capacitor legs very closely. Is the soldering intact? Do not touch them with anything metal, but you could carefully bend them just a little. If the soldering joint has cracked, it could make contact again. If it does, you can just re-solder them properly.

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On 6/21/2018 at 6:50 PM, Wild Child said:

Augus,

When inspecting the capacitors, you are looking to see if they are "blown". If they are blown, they will be bulging at the top (or may have popped open). A good capacitor is flat on top.

capblown_3.jpg

cap-blown-washing-machine-cuircuit-board-capacitor-2.png

caps-l300.jpg

Worn / overheated capacitors start to bulge at the top, but it can still fail with no externally visible damage. While basic capacitance testing in multimeters (not all have the option) can be used, to identify a broken capacitor an LC- or LCR-bridge (LC or LCR-meter) may be needed, but good ones cost upwards of 100€/100$, professional quality can be closer or above 1000. Usually the capacitor has to be first taken off the board for testing, if it's attached to the rest of the circuitry, you can't really tell much.

Late to the party, but yeah, missing torque could mean a broken capacitor. Usually they're relatively inexpensive (a few euros a piece, but shipping from a component retailer can easily be 10€/$ per order) and easy to replace, so if you have a soldering iron and some experience using it, the first thing to try might be replacing them.

 

Edited by esaj
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Ok, I've been said that springy cable should be the antenna of the Bluetooth module. I'll check capacitors legs. Thanks.

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1 hour ago, esaj said:

Worn / overheated capacitors start to bulge at the top, but it can still fail with no externally visible damage. While basic capacitance testing in multimeters (not all have the option) can be used, to identify a broken capacitor an LC- or LCR-bridge (LC or LCR-meter) may be needed, but good ones cost upwards of 100€/100$, professional quality can be closer or above 1000. Usually the capacitor has to be first taken off the board for testing, if it's attached to the rest of the circuitry, you can't really tell much.

Late to the party, but yeah, missing torque could mean a broken capacitor. Usually they're relatively inexpensive (a few euros a piece, but shipping from a component retailer can easily be 10€/$ per order) and easy to replace, so if you have a soldering iron and some experience using it, the first thing to try might be replacing them.

 

Thanks, I think I'll try to change the capacitors, to see if it solves the problem.

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37 minutes ago, Augus said:

Thanks, I think I'll try to change the capacitors, to see if it solves the problem.

I haven't taken mine apart, but based on this picture:

Kingsong-KS-16S-kontroller-1.jpg

There's a 470uF single large aluminum electrolytic near the top right of the board (partially hidden by the wires). Another cap is on the top left, but he value's not visible. What's seen is showing that t's a HKLCON CTE, 105 degrees celcius. No idea if that's the lower-voltage side, although I doubt it.

http://www.hklcon.net/en/product.asp?id=60

p1825qous21heo16vkr15joqmqo2.jpg

This datasheet seems to state that there's no values above 470uF at 100V or more (you don't want to use the 63V version on a board with batteries going up to 67.2V) for this manufacturer? The Gotway boards seem to use something like 2 x 1200uF or similar. Difference in designs? See if you can find out the actual capacitance value from the larger cap on the board. Probably both should be replaced "just to make sure".

Look for 105C or more, 100V or more, low ESR caps, using the same amount or even more capacitance (in 'sane' amounts, like not dropping a 10000uF in place of a 1000uF) shouldn't hurt, but the current spike while connecting the batteries is likely larger the more capacitance you have there.  Safest bet would probably be using the exact same make & model, but I've never even heard of HKLCON before. Usual high quality manufacturers are something like Nichicon,  Sanyo/Suncon, United Chemicon/Nippon Chemicon, Panasonic, TDK/EPCOS, Vishay...

I'm not that good at estimating the values needed, but going with the same or above the originals with voltage/temperatures/esr/capacitance shouldn't hurt unless going way overboard (like high capacity, which may shift cut-off frequencies if there are filters involved? Likely not, probably these are just "energy reservoir"/bypass caps...).

Edited by esaj
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OK, thanks for the information, I'll keep it in mind, and if I have doubts, I will change the entire board, for more security.

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Hi friends,

I want to tell you that I have solved the autobalance problem.
It turns out that I made a wrong calibration of unicycle, because I did not take into account that the wheel was perfectly vertical.
For that I have had to use two spirit levels, one to establish the posterior anterous tilt, and another to keep the monocycle completely vertical.

Greetings.

 

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I have to try it for a few days, but it does seem firm like the first day.

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Well, after trying 2 days the unicycle I have to say that it has improved with the calibration but the problem still persists. It leans forward especially when turning, and then it costs a bit to recover the horizontality. It is not a motherboard problem (capacitors, etc) because I have changed it, so I will disassemble it again and take a look at all the parts, including the motor shaft, pillars, screws, etc.

Edited by Augus

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A certain amount of tilt is normal, depending on the model. If I turn 180• in place with my 16S (fw 1.08) while holding to a rail etc, the tilt really is noticeable. If the pedals are calibrated to a forward or backwards angle, the issue is worse.

If the tilt is the same when turning left and right, I wouldn’t worry about it further than perhaps trying wether a different riding mode would help. I don’t think replacing the board would help.

Edited by mrelwood

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It's what you say, a little tilt when turning is normal.. In fact I have tuned the antero-posterior and vertical calibration, and the truth is that now I do not notice that inclination so much. 

In conclusion, I think it's a calibration issue, which is more delicate and complex than it seems.

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9 hours ago, Augus said:

It's what you say, a little tilt when turning is normal.. In fact I have tuned the antero-posterior and vertical calibration, and the truth is that now I do not notice that inclination so much. 

In conclusion, I think it's a calibration issue, which is more delicate and complex than it seems.

The calibration in the app is just for a stable position of the wheel. Then the wheel add some degrees to that depending the acceleration and 3D position of the wheel.  It's very complex. You can notice that if you are in the metro and your wheel is switched on, it will move all the time when metro turn, accelerate etc...

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On 9/11/2018 at 11:16 PM, TomOnWheels said:

 You can notice that if you are in the metro and your wheel is switched on, it will move all the time when metro turn, accelerate etc...

Being so new I didnt realize this, now I know why no matter what I do there are these subtle tilts when I'm taking long turns. 

I also noticed what mrelwood said about it being more noticeable the more degrees off level the pedals are. Going to work in dress shoes I really likes having them 3 degrees tilted back. Dress shoes like to slip forward when you hit sharp bumps like driveway entrances. I ended up back to level and taking my dress shoes with me in a bag. The effect was far more noticeable with a rearward tilt. 

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