Blown Unity Anti-Spark


Ive got a Unity that has had it’s Anti-Spark Blown. - As such I can’t turn the bloody thing off. without unplugging it.

Instead of a Loopkey solution - can i use a XT90s, and simply add it directly before the VESC to remove the “Spark”?

How do i ensure the Switch operation? - prefer roll to start disabled.

Yes. There is a whole thread on how to make an xt90s loopkey.

You will need to short (jump) the 2 momentary pins on the port of the unity switch so its “always on”

A jst ph connector with the 2 MOM pins tied together is the cleanest way.


Aware of the Xt90s Loopkey thread - im lucky enough to have 6 xt90s around, and one thats been made by Brian @b264

But this is a Complete build that needs a quick DIY fix, A loopkey would require drilling through a 2 layer enclosure to access it.
So im looking for a solution that allows me to keep everything running and a switch solution to trigger power.
After summer i’ll defiantly change that to a Loopkey.

A) Putting the XT90s - within the circut +/- both connected. Should i put it right before the postive Unity. Or on the Battery Postive side.

And why is one better than another?

B) currently when plugged in power is always on, can’t “standby” /pushto start mode.

shorting the Mom’s - is that basiclly saying that the Moms are what currently are “open” which is why i can’t power down? and by doing this i’ll be able to on/off again?

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Yes. Let’s start here though, are you sure the momentary switch isn’t just blown? The antispark is on the unity itself. Sorry if this sounds overly stupid, just keeping it basic.

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Yes, Based on the fact that the unity had water damage prior, and i tested each connector, whenever the unity is added to the circut, the spark (from the capacitors pulling power) occurs.

As for the momentary switch - i think it’s also blown but i have spares.

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an xt09s only has effect when plugging it in and completing a circuit with it not if you already have it plugged in and then complete circuit with something else

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Shame - so then how on earth does the Unity antispark - operate - same basis?

The overall goal is simply to make the board run via a switch again. if it’s just a matter of a new switch/or the pins on the Unity switch. thats good news.

On/off function is what i would like.

I would hope adding the xt90s to the circut will just prevent the spark (that only happens when plugging it in)

In which case, should it go before Unity? or right after battery (bms is bypass) charge only

As mentioned above, if you just add an xt90s to your circuit, it will still spark. The 2 stage connection when plugging it in is the antispark mechanism. I can’t speak to what specifically the unity does with its internal antispark. @JohnnyMeduse used to be the go to repair guy for escs. Not sure if he is still working on non Lacroix products though.

Seems like i should use a Antispark - Switch Module - have one spare unfortuantly on xt90’s so will have to compensate that for 60

Any ideas on how to short the MOM pins? - and what it is im actually doing by shorting them :wink:

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Use a little jst ph jumper like the one on the right. See how it just connects those 2 pins? That’s what the momentary switch is effectively doing until it dies.


My unity has the turnoff timer set when the time passes a DRV notifcation is triggered based on no shutdown - those pins are the culprits?

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I can’t say for certain but that would be my guess.

it’s probably a stupide question : wouldn’t using a push button (or whatever you call a non-momentary switch) to short those work to turn off ?
i guess it’s not enough to get it to go on, though, right ?

latching switch

technically it should work that way, but in the long run? not sure

i have seen somewhere that using the bms switch (in discharge mode) wasn’t neither a good option, but i can’t remember where it was nor why, do you have a theory ?

im not sure about the discharge bms switch part, but if i needed a solution to ur problem, i would try the latching switch first, those are easy to find and wire up for a test run

Mine is dead and i need to bypass the whole antispark module. Any anyone in the knows of how to do that.
I f*** hate shitty antisparks.

Yeah but that latching switch doesn’t give any current inrush protection so it’ll wear away over time.

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Walt, there’s probably no more than 3v 500mA on those mom pins, otherway the momentary switch would fry instantaneously, so there is an inrush protection

I mean if you can actually turn on and of the board using a switch on those two pins, it meams there’s a two stage anti-spark meant only to allow the push-start thing
Am i thinking wrong ?

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I am using my unity on the vesc tool firmware and I don’t have a switch plugged into it at all.

The roll to start is standard on the vesc tool.

Have you tried that?