I’m also interested about how you soldered the DRV given that it needs to be soldered at the back. Did you use a hot air station for the DRV and ARM chip?
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Yes, i used a normal soldering iron with some flux and soldered from the back trough the vias. Maybe thats not enough and its not making good contact…
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This should be good enough. I did this for the proto-FOCer.
Soldered 3 more today, they all released the magic smoke on R48 when i plugged them into 19V… Thats probably what happend with the first one, because now they are the same… I really dont know whats the problem, maybe some faulty DRVs ore something else is really wrong.
I first tested them on 5V and the LEDs (blue/red/green) lit up so i thougt it must be ok 
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R48 is just a resistor in line with Vcc for the DRV. This implies that way too much current was flowing through it and burning it up. This also suggests that the DRV was drawing too much current as well to cause this.
Also posting a solid, clear picture of the DRV portion (front and back) of the problematic controller(s) will help us troubleshoot.
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Did you check the DRV pins for bridges? There are a few pins that seem to be touching on the 3 boards. Not entirely sure because it’s a bit blurry when zooming on the pictures.
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True. The circled ones appear bridged.
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The second and third one on the top left also seem bridged? I can’t remember if it does matter or not on those pins though.
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Its probably just some leftover rosin flux. I already checked the DRV buck input pins for bridges, but will check more troughly tomorrow.
As of now it seems that the drv chips i ordered are faulty. It will be a pain to get them off again.
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These are connected by the PCB anyway so it doesn’t matter.
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Did some more checks for solder bridges on the DRV chips, i did not find any. The stuff on the pics is just some rosin residue from the flux.
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dang it, drv ships are kinda sold out on a couple of sites
Too much tip for too long can also kill, flat slanted tip with plenty good flux, wipe on, wipe off Daniel-San. The ground of course is not an issue with this design which is a huge plus.
Pure IPA for cleanup and the nice Japanese tissues or Q-Tips. That looked like a bridge but on closer inspection it’s maybe some remaining flux as you say.
You can run 12v for testing which is less likely to bring the 
. Spending time correcting possible problem areas with a lens is time well spent.
Get nice flux/solder/paste, it makes life easier, this kind of specialist stuff
https://www.doc-solder.ie/store/soldering-flux/RMA-Paste-Flux-10cc
https://www.doc-solder.ie/store/Soldering/Solder-Wire/Lead-Free-Solder-Wire
Some long tipped tweesers are really handy for positioning components well
I would defer to @Agressivstreetlamp @shaman @JohnnyMeduse but the above worked for me as a psuedo-noob for smd assembly, in particular the tricky DRV
Not linking lead products as you need to have ventilation solutions and there are quality lead free options from my experience
Did they all blow on R48? That is very weird unless there is a component orientation problem, bad pcbs, or as you say bad quality component
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+1 leadfree
Also, getting this working without hot air would be wildly impressive. Personally, It looks like the ARM is not aligned correctly.
Also, realize that the R at the end of DRV8301DCAR is simply a packaging thing. the Big 3 (Digikey, Mouser, Arrow) all list both. Basically, they buy the R (Bulk) and cut you off a slice.
https://www.arrow.com/en/products/drv8301dcar/texas-instruments
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I read somewhere that it is good practice to power a new soldered board with a current limiting power supply, so you dont burn chips. Do you put a little solder on the ground pad before putting on the DRV and soldering it from the back site vias?
@shaman Is the FOCer also running the Ackmaniac firmware?
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I’ve only ever used the VESC firmware. The Cheap FOCer is 4.12hw based so it should work with any Ackmaniac firmware for 4.12 hardware.
I read this post about Ackmaniac’s software and then the exchange between individuals and Trampa. It seems like others have experienced issues with the motor detection of the newer VESC tool just as I did. I think I might give Ackmaniac’s firmware and software a try.
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