Begode Master - display off

[Aztek]

Lately, maybe related to colder weather, the master's display doesn't light up when the wheel is turned on.

It just beeps very faintly, starts balancing, but the screen is off. When turned off: normal strong beep and the next start the display is working again.

Here similar thing is described, although the guy lost the screen while driving. Later he thought he fixed it by pressing a loose connector in place, only to lose it again for no obvious reason.

Another Master user told me he has the same happening to his wheel and it seems to started with the weather getting colder.

Did someone hear or see anything similar? Ideas?

Edited September 24, 2022 by Aztek

[Cerbera]

I presume you checked out the comments in that video, and discovered the other video they reference where they found the problem ?

He had to reflow solder on pins 7 and 8 of the display board connector, pin 8 previously not having any !

At least it's a 'step up', ie less dangerous than not remembering to solder the motor phase wires, like in Ecodrift's recent report !

But goddammit, we really shouldn't have to be soldering this crap ourselves. These are not cheap wheels !

Another day passes, another reason arrives to definitely tear down mine (when it gets here) and carefully examine every little part before riding...

I already rather regret my pre-order (though not quite enough to cancel it I notice!) for the minefield of problems it could contain. How are you finding it otherwise ?

 

Edited September 24, 2022 by Cerbera

[Aztek]

1 hour ago, Cerbera said:

He had to reflow solder on pins 7 and 8 of the display board connector, pin 8 previously not having any !

mine seems soldered ok, although these are two small boards with plug in (pin) connectors which is potentially a problem as with the vibrations they could go out and who knows what will happen - from screen off to cut off.

Apart from this, I am unaware what these components do and how the whole thing works, so I am uneasy tinkering with it, mildly put.

1 hour ago, Cerbera said:

How are you finding it otherwise ?

Can't say yet. Heavy is the first impression.

I'm afraid if you are not very experienced and knowledgeable in electrical/electronics stuff you can't just tear it down and check it. 

The thing is steaming pile of mess.

Edited September 24, 2022 by Aztek

[Damian Lesiuk]

I have the same problem. Wheel was waiting for one hour outside and when I came back the display was not working. I will check this connector but I have little electrical knowledge.

[Mochaboy]

I don't know if it's confirmation bias or if there's an actual theme here, but my V1 Master just started exhibiting this same behavior and it happened the day after an unseasonably cold day where the average temperature dropped something like 30-40F from one day to the next.

Symptom:  Powering on a V1 Master, you hear a faint beep from the speaker, display does not turn on, wheel can balance with no issue

{eta} Seems to be a wide spread problem:
https://www.facebook.com/1177815141/videos/653970129259087/

Troubleshooting: I can reliably get the display to turn on, but only after the power supply circuitry gets a chance to "warm up" and I did it with this procedure.
1) on its kickstand, turn on the Master (listen for faint beep)

 

2) press headlight button twice to activate strobe, wait for strobe to power up to full

3) turn off Master

4) turn on Master immediately, display now powers on and beep is full strength.  You will have about 10-20 seconds between power ups to power it on again.  After that residual energy dissipates, it's back to doing the warm up/power on sequence.  I was able to repeat this procedure pretty reliably about 10 times.

Observations

I pulled my components apart to inspect the joints and nothing was obvious.  The 3.3v daughter board referenced in that video did in fact have solder that didn't quite make it through the entire via, but I'm not 100% convinced that mattered.  The top pad closest to the plastic connector - that pad is only for anchoring the pin, the actual trace is on the bottom of the board and the solder connection on that pad was more than sufficient.

I did notice some discoloration on what appeared to be an TO-252 style Mosfet (FR6215).  Lettering was rainbow colored, and under the microscope it looked like the beginnings of some swelling - both of which are indications of excessive heat. but it was hard to be certain under so much conformal coating.

https://octopart.com/datasheet/irfr6215trpbf-infineon-65874176

I need to get my EUC closer to my work station so I can run some proper tests, but areas I'll be checking are as follows:

1) input power to the display module
2) input power to the speaker (once I find where the speaker even is)
3) gate voltage to either the mosfet or the PMIC that controls the display daughter board
4) Capacitors in the chain

Going to take some time to map out, but will post back with whatever I find.

{edit 9.29.22 Part 2)

Fascinating.  The 3.3v 8 pin plug in daughter board isn't a voltage regulator as I had originally thought.  I think it may be the thermal cut off switch.  The big 3 pin package visible on the top is an Infineon IR6218 150v Mosfet.  Apparently this part is used in temperature sensitive applications.  I've experienced the effects when I kept my Master turned on during a ride with the NYC crew.  I was sitting on top of it chatting with the crew when it hit thermal cutoff and shut off.

https://www.infineon.com/dgdl/Infineon-ApplicationNote_PowerMOSFET_SimulationModels-AN-v01_00-EN.pdf?fileId=5546d46250cc1fdf0151588db5ef1b18

Need to do some more reading

{edit 9.29.22 Part 1}
* Reverse engineering is hard without a schematic, so take all of these theories with a grain of salt.  I'm throwing this out there hoping someone smarter than me picks up this threads and adds to the research.
* Boards have all been pulled apart (will take pics), just wanted to type this all out while it's still fresh in my head.
* The motherboard consists of 2 additional daughter boards...Both are step down buck converters, one is a high voltage to 12v buck, the other is a 12v to 3.3v converter.  Both plug in via 8pin DIP connectors.  The 12v daughter board is curious because it has an ac coil transformer on it.  Brushless motors are technically asynchronous AC motors but that alternating current never makes it out of the controller to stator circuit.  I ran a quick search of similar components and it appears that design is used for high voltage DC to low voltage DC step down conversion (as well as AC 220v to 12v).

* The female board to board connectors were inspected under a stereo microscope and all the contact blades are intact however the interface between the 12v daughter board and the mainboard/motherboard is very loose.  There was a LOT of electronics grade silicone adhesive fixed to both of these daughter boards, and while that's fine for making sure stuff doesn't shake loose, you can only expect so much out of those those male pin to female socket DIP connectors.
* The symptoms reported so far suggest 1 of 2 things.  Mechanical stress due to excessive vibrations (offroad riding), Reports of cold weather also suggest contraction and expansion stress fractures on the board.  With so much current flowing through these boards, it's not altogether impossible that rapid heating and cooling can cause stress fractures in any of the solder joints, but primarily the connection points that rely on DIP connectors, since the only thing holding the pins is spring tension in the female sockets.  The motor driver board itself is fixed the controller box with a thermal pad so they were expecting to dissipate a lot of heat from these components.  Question is how much?

* Another thread I'm chasing down is how the display can power up once the system is "warmed up".  The trick is fooling the euc into powering up the entire circuit, which you can do by powering on the strobe while the euc is on its kickstand.  The challenge with chasing down this thread is that you need a circuit map to verify how parts are powered on.  Are they powered through a single solid state switch?  Or are there alternate power up pathways.  The fact that the driver board gets enough power means it's getting 3.3v to power the MCU, and 134v to power the magnets, but not 12v to power the display (there's a pin on the display board that says 12v so I'm assuming it needs that much, although that's a curious voltage to feed a digital display).  The fact that everything turns on after a quick power down, but fails after a certain amount of time passes suggests there is residual power stored in the capacitors that powers the display circuit through some alternate path.

* There is a single TO-252 Mosfet that I "think" is the power on switch.  The actual tactile power on switch, shorts a power on signal pin to ground which sends yet another signal to a solid state switch.  The reason (I think) a Mosfet is used in this application is because of the high voltages involved (International Rectifier FR6215 - this is a mosfet capable of up to 150v...so right in spec with the application).  The gate voltage of that mosfet is 2-4v so that will be an easy thing to check once I have everything reassembled.  Weird thing is what is a 150v capable switch doing on a 3.3v motherboard.

* After reviewing similar threads on Facebook (posted above), there's a growing mountain of evidence that suggest this is a temperature induced issue.  Temperature related failures usually conclude with 2 things:  a part in imminent danger of failing (as reported in that facebook thread), or a stress fracture from rapid expansion and cooling.  Stress fractures are not clear breaks as they can exhibit intermittent connectivity, but also increased resistance (not enough of a contact patch to deliver the necessary current).  Short of reflowing the entire board, I can't think of a good fix for this until we nail down which component is affected.

Weird stuff I'm considering:
* the DIP connectors don't make any sense to me, especially considering how much vibrational stress these components experience.  If I can install longer connectors on those daughter boards, I may be in a position to solder them directly to the mainboard.
* Using this is a justification and buy an ESR meter.  You can use these to test capacitors in situ (in circuit) and see if any of the electrolytic capacitors is malfunctioning without having to desolder them.

 

Edited September 29, 2022 by Mochaboy

[Aztek]

17 minutes ago, Mochaboy said:

I don't know if it's confirmation bias or if there's an actual theme here, but my V1 Master just started exhibiting this same behavior and it happened the day after an unseasonably cold day where the average temperature dropped something like 30-40F from one day to the next.

Symptom:  Powering on a V1 Master, you hear a faint beep from the speaker, display does not turn on, wheel can balance with no issue

Troubleshooting: I can reliably get the display to turn on, but only after the power supply circuitry gets a chance to "warm up" and I did it with this procedure.
1) on its kickstand, turn on the Master (listen for faint beep)

2) press headlight button twice to activate strobe, wait for strobe to power up to full

3) turn off Master

4) turn on Master immediately, display now powers on and beep is full strength.  You will have about 10-20 seconds between power ups to power it on again.  After that residual energy dissipates, it's back to doing the warm up/power on sequence.  I was able to repeat this procedure pretty reliably about 10 times.

Observations

I pulled my components apart to inspect the joints and nothing was obvious.  The 3.3v daughter board referenced in that video did in fact have solder that didn't quite make it through the entire via, but I'm not 100% convinced that mattered.  The top pad closest to the plastic connector - that pad is only for anchoring the pin, the actual trace is on the bottom of the board and the solder connection on that pad was more than sufficient.

I did notice some discoloration on what appeared to be an TO-252 style Mosfet (FR6215).  Lettering was rainbow colored, and under the microscope it looked like the beginnings of some swelling - both of which are indications of excessive heat. but it was hard to be certain under so much conformal coating.

https://octopart.com/datasheet/irfr6215trpbf-infineon-65874176

I need to get my EUC closer to my work station so I can run some proper tests, but areas I'll be checking are as follows:

1) input power to the display module
2) input power to the speaker (once I find where the speaker even is)
3) gate voltage to either the mosfet or the PMIC that controls the display daughter board
4) Capacitors in the chain

Going to take some time to map out, but will post back with whatever I find.

 

That's the phenomenon exactly.

Actually, I think the two small boards were a bit pulled out of the connectors they are plugged in. They were somewhat loose. I pressed them back and plan to fix them with hot glue, to stay in place despite the vibrations.

You sound competent in the matter, so, by all means, do write back your findings. The problem is widespread, as it seems.

[Mochaboy]

So looks like Begode confirmed that the power on threshold is about 20C/68F.  They're working on a firmware fix to address this issue.

That theory about the temperature threshold on the power on Mosfets looks to have been the culprit. 

Yay for us

[Aztek]

40 minutes ago, Mochaboy said:

So looks like Begode confirmed that the power on threshold is about 20C/68F.  They're working on a firmware fix to address this issue.

That theory about the temperature threshold on the power on Mosfets looks to have been the culprit. 

Yay for us

Where did you see a confirmation? Could you share a link, please?

[Mochaboy]

Discord Begode Gotway channel.  It was reported a few weeks ago and the person who reported it was in direct contact with the Begode folks.

https://discord.com/channels/301222762133848064/767986046654087199/1025085166235951134

https://imgur.com/a/YN0Z4EN

 

[Aztek]

51 minutes ago, Mochaboy said:

Discord Begode Gotway channel.  It was reported a few weeks ago and the person who reported it was in direct contact with the Begode folks.

https://discord.com/channels/301222762133848064/767986046654087199/1025085166235951134

https://imgur.com/a/YN0Z4EN

 

So is it a hardware problem? How could it be fixed by software then?

More importantly, is it something which can cause fire or sudden cut off?

[melheor]

53 minutes ago, Aztek said:

So is it a hardware problem? How could it be fixed by software then?

More importantly, is it something which can cause fire or sudden cut off?

Based on the screenshot in the post you quoted, it seems like a software problem (screen not booting up until temperature reaches 20C, it should be able to boot up with lower temperature), which is consistent with the post by Mochaboy. Where are you seeing an indication that it's a hardware problem?

[Cerbera]

Well I'm glad I read this thread before opening mine up in a UK Autumn / Winter ! What sort of crazy design led to the display only working over 20 degrees ?!

 

 

Edited September 29, 2022 by Cerbera

[Cerbera]

On 9/24/2022 at 10:48 AM, Aztek said:

I'm afraid if you are not very experienced and knowledgeable in electrical/electronics stuff you can't just tear it down and check it. 

Perhaps not, but I can certainly see if they have forgotten to solder my motor phase wires, and will be able to check simple but important things like that there are no screws or other parts missing, and can ensure no cables are getting crushed between surfaces / padding etc before first use. In that same teardown I will remove the battery cover plastics, check their wiring, and then properly pad them in all the areas still exposed. May also change tyre, but TBH, with the litany of incompetence we have seen in the manufacture of these machines ANY check at all, expert or not, is better than none !

Edited September 29, 2022 by Cerbera

[Mochaboy]

On 9/29/2022 at 4:28 PM, Aztek said:

So is it a hardware problem? How could it be fixed by software then?

More importantly, is it something which can cause fire or sudden cut off?

The information shared with me was the following:
* priority is finalizing master x/master pro firmware

* display boot issue is "minor" {quotes mine} and engineers suspect the motherboard isn't sending a boot signal to the display in cold temperatures {duh}.

* test firmware "may" be available mid October...for whatever that's worth...

...
And at the risk of muddying and complicating the discussion further, a local Begode dealer has also relayed the same issue to Begode that was reported to him, and the information shared with him was that they'd be sending him a new display board after the Chinese holiday.  He seems to think it's hardware related...I'm of the opinion it's firmware related.

***
Not that I'm in a position to allay concerns about this being to connected to the rider that reported his display was malfunctioning prior to his board shorting and blowing up, it's my opinion that while regrettable, the two issues are not connected...just extraordinarily bad luck.  Watching his teardown - there were indications one of the two electrolytic capacitors on the driver board simply failed.  Having log data handy would help to have nailed down whether it was caused by voltage overload due to regenerative braking, or some other voltage related factor.  Just making the case to say if you're riding and having issues with the mainboard - consider data logging your rides in the unfortunate event something happens and you go down.

Other thing I'd encourage you all to do is go to the Begode/Gotway Electric Unicycle facebook group and log threads there (and link to this one) so we can keep this on top of their development queue.

That's all I have...if you guys hear anything different please share back.  Make sure you suit up when you ride

[Aztek]

Electrolytic condensators you say... These tend to open, leak and dry up with time and the resulting board behaviour is nothing less than erratic after. Transferring my PC motherboard experience through the years.

Yet another thing to worry about.

[DXKI]

I'm leaning more to hardware related, my light and screen will no turn on with the physical buttons on he master, but I can turn the light on with the app, unless there is a separate firmware and hardwired connection to the light, the problem seems physical, it's been happening on my master since the first time I dropped it and finally wouldn't turn on this morning after it was on and turned off properly last night, nothing else seems to be affected, so haven't decided to do a teardown.

 

As an unrelated note before I forget, 18x3 tubes fit the master with little issue (not sure if that's known yet)

[Gustesta]

Please any updates on this issue?  I've been having the same problem on my Master and T4.  So it's probably hardware related (and it's just happening now that the temperatures are low).  Thanks.

[Cerbera]

Only updates are that is happening to a lot more of us now ! For me it is very consistent behaviour - if it is 16 degrees C or under there is no display, and if it's above that there will be. Bringing the main system temp up to above 17 with  few gentle rocks it fixes every time in my case, so I do consider this a rather minor problem.

However there is a lot of inconsistency between reports of this. Some people get headlight affected too, and others, like me, do not. I think it is probably still only known to Begode (and possibly not even by them!) what the cause of these things might be. I have not been offered a replacement board by my dealer, who knows I have the problem, but I said I wasn't bothered by it, and we had other, more potentially worrying problems to solve...

[Gustesta]

3 hours ago, Cerbera said:

Only updates are that is happening to a lot more of us now ! For me it is very consistent behaviour - if it is 16 degrees C or under there is no display, and if it's above that there will be. Bringing the main system temp up to above 17 with  few gentle rocks it fixes every time in my case, so I do consider this a rather minor problem.

However there is a lot of inconsistency between reports of this. Some people get headlight affected too, and others, like me, do not. I think it is probably still only known to Begode (and possibly not even by them!) what the cause of these things might be. I have not been offered a replacement board by my dealer, who knows I have the problem, but I said I wasn't bothered by it, and we had other, more potentially worrying problems to solve...

I've been getting the exact same problem you described (on my Master and T4): on cold temperatures the display won't turn on, but after it gets warmer it works.  I've asked my dealer for a possible solution.  I'll let you know.  So far it is a temperature related issue for sure.

[Rawnei]

Can confirm I have the same issue on my Master V2.

[Cerbera]

For the sake of completeness I should add here also that Begode have since sorted this out, designed a new satellite board that fixes it, and if you approach your dealer they will be able to send you a free one.

[Rawnei]

14 hours ago, Cerbera said:

For the sake of completeness I should add here also that Begode have since sorted this out, designed a new satellite board that fixes it, and if you approach your dealer they will be able to send you a free one.

Do you happen to have a source for that?

I sent my reseller a video of the problem but they are asking me on behalf of Begode to open up my wheel dismantle motherboard to check if the daughter-board in question "is well", I don't even know what they mean by that so I asked for clarification.

A local rider had the same problem and they sent him a replacement board, I've asked him what he had to do also.

I just got everything assembled again from waiting for the replacement battery and honestly all this jumping through loops is so frustrating, if there is an official statement from Begode somewhere that would be great.

[Bizra6ot]

@Rawnei https://www.facebook.com/groups/ElectricUnicycle/posts/5540149159416335/

Kebye GotWay
 its this part as photo problem for new model include master x ,pro, and master ,T4 when under low temperature but not screen problem

Kebye GotWay
 just before days we found the same problem ,and now we found problem and solved ,please change current limited protect model , get the part from u seller please

[Rawnei]

8 minutes ago, Bizra6ot said:

@Rawnei https://www.facebook.com/groups/ElectricUnicycle/posts/5540149159416335/

Kebye GotWay
 its this part as photo problem for new model include master x ,pro, and master ,T4 when under low temperature but not screen problem

Kebye GotWay
 just before days we found the same problem ,and now we found problem and solved ,please change current limited protect model , get the part from u seller please

Thanks, exactly what I was looking for!

[jmac61570]

Yes. I am having the same issue. Same symptoms. I live in Seattle cold weather is kicking in. However, now I am leaving it in the house and not the garage. It works normal now. I spoke with Alien Rides where purchased my master from and they told me that it’s a known issue and they will have something that will be sent to them to fix the issue. Something about a PCB board. So hopefully this is what will fix it. 
JM