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Sherman short circuit (horrible design choice)


UniGrad

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This has been on my mind since I saw the design of the Sherman but I assumed that Veteran was aware of the potential issues so I didn't mention anything about it.
 
I have been involved in the design of various electronics products and we have used the same 3.5mm audio jacks that the Sherman uses for the front and rear lights.
Throughout our years of working with these audio jacks we learned 1 very important thing about them. They are EXTREMELY susceptible to short circuiting.
All you need to do to create a short circuit is have the connector partially plugged in. In other words if it becomes a little loose, you can get a short circuit. There's absolutely no getting around this fact.
It's a consequence of the linear design of the connector where you can easily bridge the gap between 2 terminals by shifting the position of the connector (i.e. to a partially unplugged position).
 
Knowing this though, I thought that Veteran must have taken this into account and assured that there would be no consequence if the connector becomes loose and creates a short circuit. 
 
I was wrong!!!!!!!! :mellow:
 
The rear 3.5mm connector became partially loose from going over a rough section of road. I noticed this after I came to a stop. At this point everything was still fine and no short circuit had occurred. Then I simply went to plug the connector back in properly and a short circuit occurred.
This is what happened next. The rear light completely stopped working and now I need a new one. And the wheel turned itself off. Also the front light flashed on and off real quickly. But the front light is still fine and the wheel is still fine. I turned the wheel straight back on and it was fine. Just the rear light died.
 
But the real concern is the question of what would have happened if the short circuit occured while I was still moving. Would it have still turned itself off and caused a cut out? If the answer is YES then this is a MAJOR problem.
All it would take is a partially loose connector to cut out the wheel. This is far from acceptable in terms of safety. The 3.5mm connectors are far from bulletproof and they can easily be rocked out of position over time.
 
I am suggesting that this needs to be tested. Test to see what happens if the wheel is moving when the short circuit occurs. Feel free to try it when the wheel is stationary and see what I saw. See that the wheel just turns itself off. All you need to do is wiggle the connector out a little bit and it easily creates a short circuit. This is just the way these connectors work and there's definitely nothing wrong with this particular connector.
 
Can't wait to see the result of this test. I may get around to testing it myself soon but don't have the proper stand at the moment. If someone else tests it first then please make sure to post the results here.
All you need to do is put the wheel up on a stand that lets the wheel spin. Then get it spinning up to some normal speed like 20 mph, then while it's spinning, wiggle the rear audio connector until it creates a short circuit. WAIT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
This will actually kill your rear light just like it did to mine. So instead of doing that, use some cheap headphones instead. Plug those into the wheel in place of the rear light. But make sure the wheel is off before unplugging the rear light or you might create the short circuit and kill the light.

Then there's the question of the front light. I don't know what happens when you short circuit that connector. But it's equally important to test this one because it uses the same type of connector with the exact same short circuiting issues.

Screenshot (533).png

Edited by UniGrad
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25 minutes ago, rexdelmolvo said:

Ough, this is kinda scary. Wonder if we should take some precautions to really lock the plugs in place?

That's definitely going to help but I still wouldn't feel comfortable riding this thing if it turns out that it will cut out during movement.

If it turns out that it does cut out it would be beyond laughable. Only a bunch of clowns would come up with something like that. But let's wait and see the results when someone gets around to testing this.

Even at the moment though I'm not happy at all about how the rear lights will just fry themselves if the connector becomes loose. A horrible design choice indeed. Now I have no rear light.

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open it up and solder a proper connection? I think the turn signal is useless and cheesy anyhow. I may just mod mine for better connector and just single light. Silicone until I void the warranty thru other means or time, maybe? Perhaps its as good excuse as any, to find an uber bright strobe for the brakes? THanks for the heads up!

Edited by ShanesPlanet
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50 minutes ago, ShanesPlanet said:

open it up and solder a proper connection? I think the turn signal is useless and cheesy anyhow. I may just mod mine for better connector and just single light. Silicone until I void the warranty thru other means or time, maybe? Perhaps its as good excuse as any, to find an uber bright strobe for the brakes? THanks for the heads up!

If it turns out that it won't cut out during motion then I won't bother opening it up. Can't be bothered with those chores. I'll just use some kind of glue and that should prevent it from coming unplugged therefore preventing the light from ever burning out.

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I replied with this on the Facebook post of this thread:

 

I have shorted my front headlight accidentally whilst making a new front light. I had made four prototypes before I accidentally shorted the flashing light circuit to ground. Now my light is permanently on, so I have to unplug the connector whenever I don't want lights. However, the short did NOT cause a cutout. The wheel continued to balance just fine.

On the plus side I have a custom light that combines a nice far throw with a wide spread so I have good all round lighting. It's not a major inconvenience for me, and I suspect all that has happened is perhaps a relay has fused closed. Unless the lights are controlled by a mosfet? Not sure. I'm an amateur with this — just wanted better lighting and no stupid flashing lights!

IMG_4465.jpeg

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3 minutes ago, Dominic Winsor said:

I replied with this on the Facebook post of this thread:

 

I have shorted my front headlight accidentally whilst making a new front light. I had made four prototypes before I accidentally shorted the flashing light circuit to ground. Now my light is permanently on, so I have to unplug the connector whenever I don't want lights. However, the short did NOT cause a cutout. The wheel continued to balance just fine.

On the plus side I have a custom light that combines a nice far throw with a wide spread so I have good all round lighting. It's not a major inconvenience for me, and I suspect all that has happened is perhaps a relay has fused closed. Unless the lights are controlled by a mosfet? Not sure. I'm an amateur with this — just wanted better lighting and no stupid flashing lights!

IMG_4465.jpeg

That's great to hear. I suspected it wouldn't cut out. But we still need to test it for the rear ones.

Whoa those lights look mean......... yet friendly. Looks like Sherman got a pair of eyes. Looks like a smart fellow.

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Haha yes — and I've crashed it down a hill a few times, they're still working fine!

@UniGrad if you are experienced with electronics I'd love it if you could help me out — can you take a look at the control board and see whether there is in fact a relay that is used to switch the main light on and off? I suspect that if there is, mine is fused shut due to my accidental short, hence the lights are permanently on and not switchable by either the button or an app. 

If I can't have it repaired, a new control board is about £300 GBP. So I will probably just live with it!

Also, here's my original post on the topic: 

 

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3 minutes ago, Dominic Winsor said:

Haha yes — and I've crashed it down a hill a few times, they're still working fine!

@UniGrad if you are experienced with electronics I'd love it if you could help me out — can you take a look at the control board and see whether there is in fact a relay that is used to switch the main light on and off? I suspect that if there is, mine is fused shut due to my accidental short, hence the lights are permanently on and not switchable by either the button or an app. 

If I can't have it repaired, a new control board is about £300 GBP. So I will probably just live with it!

Have you considered using a switch inline with one of the power wires (Gnd or +ve) going to the light? This would be the easiest way to be able to switch it on/off.

I could take a look at the control board when I get the chance but I have yet to open my wheel so I don't know what it looks like yet.

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My tail light is also unresponsive but the port is giving out 5V.
Diagnosticating the pixel array signal gets a bit complicated for me, and I'd like to just put a red 5V light there.
There doesn't seem to be much or any 5V tail lights available, anyone know of any?
Else I consider making something with this, two 2.5V in series should make 5V. Any reason not to?

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1 hour ago, null said:

My tail light is also unresponsive but the port is giving out 5V.
Diagnosticating the pixel array signal gets a bit complicated for me, and I'd like to just put a red 5V light there.
There doesn't seem to be much or any 5V tail lights available, anyone know of any?
Else I consider making something with this, two 2.5V in series should make 5V. Any reason not to?

why not buy the 3.7v and run it hot? You could also step it down with a resistor, but if the sherm is 5v, maybe those leds can take it? If cheap and easy, does it matter if they dont live quite as long? I dont see any reason you couldnt run 2.5v in series either. Just be mindful of amperage is all. 5v is usb range power aint it? I'm surprised you havent found anything decent on that voltage.

Edited by ShanesPlanet
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14 hours ago, UniGrad said:
Then I simply went to plug the connector back in properly and a short circuit occurred.
This is what happened next. The rear light completely stopped working and now I need a new one.

Strange that a short circuit destroys zhe back light but leaves the driver circuitry intact?

1 hour ago, null said:

My tail light is also unresponsive but the port is giving out 5V.
...
Else I consider making something with this, two 2.5V in series should make 5V. Any reason not to?

It seems that the driving circuitry survives (?short time?) short circuits. Maybe it's a current source for the rear led just maxing out at 5V with no load?

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6 hours ago, UniGrad said:

Have you considered using a switch inline with one of the power wires (Gnd or +ve) going to the light? This would be the easiest way to be able to switch it on/off.

I could take a look at the control board when I get the chance but I have yet to open my wheel so I don't know what it looks like yet.

Yes — I might well do that.

The control board is SUPER easy to access. Look at the post on this forum on doing a firmware update to see how quickly you can get in there.

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1 hour ago, Dominic Winsor said:

Yes — I might well do that.

The control board is SUPER easy to access. Look at the post on this forum on doing a firmware update to see how quickly you can get in there.

Switch in line is what I would do. Plus you could pick a bad ass switch too...

I'd post this thread in the Veteran sub forum. I rarely come here but this is a major deal to riders. Testing must be done. I have a V11 and am quite happy but Veteran Sherman 2.0 will be my nest wheel. 

Edited by EUChristian
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7 hours ago, Chriull said:

Strange that a short circuit destroys zhe back light but leaves the driver circuitry intact?

I'm not sure that the driver circuit is entirely intact. But it does still put out 5V across 2 of the terminals as it normally does. I know this because I'm using this 5V supply to power a bluetooth speaker that I attached to the wheel.

But the thing I haven't checked is if the on/off function still works on that driver circuit. Not everyone knows this but if you quick press the power button on the Sherman, the rear light will toggle on/off. So I'm not sure if that part still works. It's possible that it was damaged during the short circuit but I won't test that until I get a new rear light. If the on/off feature turns out to be damaged it wouldn't bother me though. Not much use in being able to turn off the rear light. And if it turns out to be permanently off then I could just use an aftermarket light that runs on 5V.

Okay talking about this now made me aware of another possibility. Maybe the light is still fine but part of the circuit that drives the light is damaged. Namely the part that gives the control signal. Like I said the 5V across 2 of the terminals is still there. But there's a 3rd terminal that gives the control signal of about 1V. Maybe it's that part that's not working and it's keeping the light constantly off. Come to think of it, that's a strong possibility. Well the solution is still the same, get an aftermarket tail light that runs on 5V.

9 hours ago, null said:

My tail light is also unresponsive but the port is giving out 5V.
Diagnosticating the pixel array signal gets a bit complicated for me, and I'd like to just put a red 5V light there.
There doesn't seem to be much or any 5V tail lights available, anyone know of any?
Else I consider making something with this, two 2.5V in series should make 5V. Any reason not to?

Yeah sounds like the same thing happened to your tail light. Mine is also fried but the port still gives out 5V across 2 of the terminals. If you read what I wrote just above this, you'll see that now I'm not sure if my light is fried or part of the circuit that drives the light is fried.

1. If it turns out that the light is fried and the circuit is fine, then you could simply buy a new Sherman tail light and use it to replace the bad one.
2. If it turns out that the circuit is damaged but the light is fine then you would have to buy an aftermarket tail light that runs on 5V. Although the circuit may be damaged, it still puts out 5V so it's still useful for powering a light. It just may not be powering the Sherman light because that light relies on a 1V control signal coming from the 3rd terminal on the 3 pin audio connector. It uses this control signal to achieve the on/off feature of the tail light. But that's a pretty useless feature so having an aftermarket tail light that is always on would be just as good.

I will find out whether the case is 1. or 2. once I get a new Sherman light and try it out. If the new Sherman light works, then it means that the circuit is fine and the old light got fried. But if the new Sherman light doesn't work it means that the circuit got damaged and the control signal no longer works. In which case an aftermarket 5V light would be the answer. I could try to diagnose it with a multimeter but without knowing the specs of the control circuit I wouldn't be 100% sure on the result. So I'll just wait to get a new Sherman light and use that to diagnose the issue.

I wouldn't bother with 2x 2.5V lights. I'd just get a good 5V light.

8 hours ago, ShanesPlanet said:

5v is usb range power aint it?

That's right. USB runs at 5V so there should be some 5V lights available out there. I'll have a look around in the next day or two and post what I find.

1 hour ago, EUChristian said:

I'd post this thread in the Veteran sub forum.

Do you mean I should just post the original post in the Veteran sub forum. Or is there a way to link this post so people can see this whole thread?

Edited by UniGrad
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6 minutes ago, UniGrad said:

Do you mean I should just post the original post in the Veteran sub forum. Or is there a way to link this post so people can see this whole thread

If you like i can move this topic. Would imho fit into the veteran subforum.

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3 hours ago, Dominic Winsor said:

The control board is SUPER easy to access. Look at the post on this forum on doing a firmware update to see how quickly you can get in there.

That's nice to know. I had heard from somewhere (can't remember where but it was probably an unreliable source) that the Sherman was extremely annoying to open up. So I was dreading ever having to open it. But of course at some stage we always have to open our wheels so that's really good news.

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I noticed this when I was unplugging the rear light. If you partially plug it in its always on. I think a dab of silicone or hot glue will keep it in place. 

 

If you want to fix it you can just put a mini fuse in line and then you don't have to worry about it. 

Edited by Fiori
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4 hours ago, UniGrad said:

That's nice to know. I had heard from somewhere (can't remember where but it was probably an unreliable source) that the Sherman was extremely annoying to open up. So I was dreading ever having to open it. But of course at some stage we always have to open our wheels so that's really good news.

the sherman is shit simple to open up. You neednt even remove the trolley. To get to the board, you only have to open the top panel. Its 4 screws, find purchase into brass inserts. Amazingly enough, I have to admit the board looks of good manufacture and is well built and coated. See, they CAN do shit right, IF they wanted to.

Edited by ShanesPlanet
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  • 1 year later...
56 minutes ago, Kekafuch said:

Was there any further tests to a short causing a cut out? 

I'm 99.9% sure that it doesn't. But it can fry the data signal output on the board, as mentioned above.

On 1/8/2021 at 8:53 PM, UniGrad said:

It uses this control signal to achieve the on/off feature of the tail light. But that's a pretty useless feature so having an aftermarket tail light that is always on would be just as good.

And I just saw this...the data signal doesn't just control the on/off for the light. It's also activates the left/right banks of LED's when turning, as well as the brake light (which I find very handy during group rides).

I would really like to find an alternative light that still has the braking feature (not fussed about the turn feature), only cos I think the stock light looks utter shite.

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