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@cw_o Welcome :)

If the price is okay I'd take the risk. Getting actual chips from companies like Mouser, Digikey and LCSC can be pricey once you get to the shipping screen. I've gotten chips from eBay and AliExpress (likely the same source) without many issues for things like IMUs, Mosfets and a handful of logic ICs.
Get multiple though just in case you need to redo it. No more than 5 should be fine. IMU's are fragile so you may need to try a few times.

@cw_o

• If they have a reflow/hot air station then that's the tool you need :) Air for the chip and an iron to touch up the pads.
• Before removing the chip make note of it's orientation for when you replace it.
• Use some isopropyl alcohol and a cotton swab to clean the area and remove some of the conformal coating. It'll get in the way otherwise and possibly compromise a good solder job.
• 180c-200c on the hot air station should be fine to get it off without putting too much heat in the pcb. If you find after a minute it's still not showing signs of moving you can carefully increase the temp but not by much.
• Airflow setting somewhere in the middle. Not so much it flings off parts but not so slow it doesn't put heat in fast enough to fight the power planes heat dissipation.
• Don't hold the heat in one spot as you can popcorn a PCB. Rotate it around the chip so that you get a more even distribution of heat.
• Flux is your friend and will help get under the chip to get the solder molten.
• Don't pry it off, wait for it to be loose and lift up gently with tweezers.

• Once off clean up the pads gently with some solder wick and then use some cotton swabs to take up some flux before cleaning and visual inspection to make sure all pads are good.
• When wicking it's best to cut off a small section and press the iron onto the wick. You can move gently over the top with the iron or if easier use tweezers on the wick.
• Don't pull too hard as the pads can momentarily solder to the wick and tug which can result in a torn pad. If you find the wick has become soldered just apply flux and hold the iron there for a few seconds then try to move it sideways gently while still applying heat. Never pull the wick up.
• As the pads for this chip are under it you'll need to prepare the pads with solder before placing the chip. Go over with a soldering iron and pre-tin them so that they are slightly raised enough that they'll contact and flow onto chip. Not too much that they might squish and bridge. Bit of an art to knowing how much is right. Make sure this iron doesn't get too hot. The pads are delicate and too much heat from an iron can cause them to de-laminate.
• Apply some flus in the middle of the pads where the chip will sit and place it on top as centered as you can get it.
• Bring the hot air back over. The flux will melt and pool around the chip. To stop it shooting off I prefer to try hit it with heat top down so the air doesn't try to blow it away wince we're not holding the chip.
• Eventually you should see it wiggle into place as the solder and flux pull it into alignment. You can give it a gentle tap with the tweezers to make sure it's actually soldered because it'll snap back when slightly poked.
• You can press down a little on top to squish the solder and make sure all pads flowed to the chip. Don't do it with force, just a little to press it down and remove the heat. Hold that for 20-30 seconds to ensure the solder ahs set and you can let go of the chip.
• Use another cotton swab to cleanup the flux and then isopropyl to get the rest of it.

Before powering on I recommend grabbing a multimeter and checking the voltage rails and some of the capacitors for shorts to ground. The caps should have 1 to ground and the other to data so if any are bad then you may have a bridged solder joint under the chip and will have to repeat the process with less solder.

Below is a reference for the traces in the area if it helps at all.

@cw_o Did the seller say what hardware revision it was. It looks like it's pre-serialisation but the 4210-4213 models complain about mismatched BMS's. It can be worked around with additional modding but it's a factor.

4206-4209 are fine so if it's one of those it'll be a simple swap.

@cheesej Great work getting that fixed! Surprised that damage was enough to break the inductor.
Thanks for sharing your process :)

@cheesej Hiya :) That's a 270uH power inductor. If there's actual damage to the windings on it that could cause issues.

The only time I've seen similar when the battery was fine is dodgy caps on the balance IC.
Cell voltages can report incorrectly if any of the caps around the balance chip at the other end of the pcb are slightly detached or faulty. Common to do when unplugging the XT60 and bumping one.

Might be worth giving this post a lookover to see if your board is doing similar if the inductor doesn't solve the issue.
https://owforum.co.uk/topic/403/xr-overcharged-cell-that-isn-t-after-battery-upgrade-repaired

@onedangts-xl The tire size increase was a must on the GT side. I mean the frame itself looks so much better now with the larger tire.

Speaking of, how is the tire?

At Opensauce the GTXS and XS got up to some shenanigans. The Friday afterparty comprised mostly of it and Wren's VESC showing off.

During the Friday setup I was asked to help Ivan Miranda repair his " wheeled Onewheel. I assume he'll have a video on that project at some point. However after we got it working I took a few chances to get a few pics with it.

Future Motion's Alec came to visit us and left his XRC with us while he checked out the rest so we used it as an opportunity to show the scale.

SimpleFOC's robot dog came to visit again and we handed over a little award for riding the first one.

Not long after we set off to Santa Cruz and spent some time with FM. We were only in the lobby this time which unknown to us meant there were some GT XLs around the place. Regardless we had some fun helping film some silly promotional clips and showing the team the little boards again.

We hadn't finished our little trip to Cali yet though. The next day we shot up to Sacramento to visit TFL. Sadly as we pulled up Jeff was leaving as he was ill but the rest of the gang were stoked to see it. Nico especially who after tweaking some of my settings managed to ride it. I have yet to upload the videos of that yet so just trust me bro™

Sadly the video for the above was deleted and nobody knows where it went or how to recover it but TFL did a really funny sketch about Nico handing over a regular sized board to Keaton who then holds the XS.

Some work needed doing for the charger so I got some parts made up and painted.

Tuning the GTXS was a bit of a challenge. I know a bit more about it since rawdogging the XS with just vanilla VESC so with Refloat installed I was able to get it to a near Apex-like tune. And as an added bonus... this

To get the right look for the rails I did some testing with the plastic ones and found I could get away with some resin printed stencils BUT the XS Series decal was way too fine to get spray paint down reliably so one of Nick's friends managed to make a sticker the right size and that worked out for it. The rest are painted on top of a light coating on the anodised rails.

Inside there's a USB PD trigger to request 20v. This then goes to a CC/CV boost converter set to charge a little over a regular 7s setup at 1A. I went a little over to account for the voltage drop from a reverse polarity diode I added that also protects the charge port from exposing Batt+. Even with a cover over the magnetic port I wasn't keen on leaving that exposed.

With the metal parts the build was getting heavy. Without it all together we were already at 3.2kg. Despite this it was able to bonk a little. Sadly the footage I have of this is hella low res for some reason. However it was enough to get a repost on stories from Bohdi on Insta so that's pretty dope.

With a few final touches and accessories to bring with we had it all good enough to bring to Opensauce.

I'll try keep this short 😅

Tire was moulded using a 2 part silicone mould with 3d printed inner and outer casings to assist in registration and demoulding. The silicone was made like last time by printing a master with a 0.2mm nozzle at 0.06mm layer height. This was filled and sanded to get an even smoother finish.

That resulted in this majestic bit of rubber

Shortly after I took delivery of the CNC, 3DP and new PCBs from JLC and they looked amazing! Cost about £1k after shipping and taxes buuuuut... like look at how good these came out.

Around this time I also got a thermal camera that I started sanity checking my work. Surprisingly the hottest parts were the 5v buck converter and STM32 package. The FETs even under load and DRV chip were chilling. Likely due to the thermal considerations I took but still they barely got warm. Being Pint FETs I guess it makes sense.