The magic smoke came out of my Xenith :(

DIY Builds
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I’ve had a small 6S board working on and off in various states for a few years now, powered by a Focbox. A few months ago I decided to make a much larger 10S board and bought a BKB Xenith from Ben Buckler Boards here in Australia.

Today I finally got to the point of plugging the battery into the Xenith. I very carefully checked the battery voltage - exactly 38 volts. I very carefully checked that the polarity was correct. I held my breath and plugged it in. No sparks, no smoke, no pop. I pressed the included on/off switch and lights start flashing in a promising way.

So I brought the board over to my computer and plugged it into the USB. Windows detected it and I opened VESC tool 3.00. I was just wondering why it thought the Xenith had a newer FW version than VESC tool supported when I heard a quiet pop from the Xenith.

I unplugged things as quickly as possible, but before I did some of the magic smoke came out, which as we all know can’t be put back in once it escapes. Feck. Well I guess I won’t be building this board any time soon. I do have like a dozen other projects waiting to be worked on though so not a huge deal :stuck_out_tongue:

Upon removing the heatsink I was immediately assaulted with the most intensely vile- and poisonous-smelling melted-electronics odour. After I recovered and made it back into my room by holding my breath, I managed to get a photo. One of the DRVs is totally toast. Absolutely no clue what happened here. I’m just hoping BKB or Ben Buckler will be willing to do a warranty swap; I hadn’t filled out the warranty form since it requires a photo of the installed Xenith and I hadn’t gotten that far yet :neutral_face: Australia has fairly strong protections against stuff that’s DoA or not fit for purpose so I guess it just depends whether it really was DoA or I somehow killed it. I was extremely careful not to allow any soldering or wire-stripping debris anywhere near any electronics (including the Xenith) so I’m not sure what caused what I presume must have been some sort of short.

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Anyway I just thought people might be interested to see yet another dead DRV. I’m still comparatively new to the esk8 space but from what I’ve seen, popped DRVs have been a long-running feature of VESC-based ESCs.

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Those are the pins on the stepdown regulator.

This might be a DOA.

This indicates firmware corruption.

power glitching from a faulty DC-DC converter can cause firmware corruption.

My guess is cold joint or something else caused the buck converter circuit to misbehave. This caused firmware corruption and eventual device destruction.

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I believe Xeniths ship with the legacy Unity firmware. That’s why the VESC Tool 3 would report it as incompatible. Since the legacy firmware version is something like 23.48 (which is a high number), it may just as well be reported as “newer”.

However, this definitely has nothing to do with the magic smoke.

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Sounds like the vendor needs to take action

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The melted part is one of the DRV chips. Are you saying those pins are connected to the step down regulator elsewhere on the board?

It was indeed a number like 23 dot something. My assumption was that it was some weird old version and I was just about to flash it to the VESC tool’s included Unity firmware to make sure it was on a valid firmware when it went pop.

The vendor will if I have any say in the matter lol.

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The stepdown regulator is in the DRV

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Ah, I considered that possibility but I’m on my phone and didn’t feel like looking up the datasheet for those chips to see.

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