Attempting the unfukkering of a fukkered FocBox

If you don’t know our friend @fessyfoo blew the fukk outta his FocBox
at least 2 FETs were effected:

and it looks like the shunt resistors took a beating as well:
in fact one phase wire may have become destabilized and shifted due to the heat?? I fisserated that lead and cleaned up the two small capacitors:
I took the PCB to the hot air station and eliminated one FET

The second FET fought back… 1/2 of the FET welded itself to the solder mask and copper

I got most of it cleaned up:
after all this I ran a continuity check on the main battery leads and after the capacitors drained there was no continuity between the positive and negative leads… sounds auspicious…

regarding the FETs, from any three of the distinct solder pads either side of the FET there is continuity, and there is NO continuity between any of the solder pads and the copper trace that was under the FET… I think this is GOOD… expert opinions desired…

Do you think this BoxOfFoc can be saved? any idea of where I can get a BOM for the required direct FET?
(I can just make out l(diode symbol)R 7759 TSJ7 1447) on one FET and l(diode symbol)R 7759 TS4N 1447) on another…

Do you think as it sits it’s safe to power this up with a fused smoke stopper?

should I quit and go have a margi and a joint?



how the F did i miss that. ? i feel dumb right now.

do you think that heated from the blown fet event? or was more likley part of the event causing everything to blow?

the backstory


As I side note, I affected THC-a decarboxylation when I inadvertently used a pin, that I cleaned my vape, covered in some dank resin, and made a k00l toxic vape with lead solder and some awesome gooey resin


this is what i observed on working focboxes.


I seriously doubt the fukked phase lead caused the event… it wasn’t contacting anything, was this was standard JayPooPoo quality shit or was that phase lead joint heated enuff to shift… I dunno… It’d have to be pretty fucking HOT to melt that lead solder…

but there was definitely fukktons of heat evident in the Box and on the shunt resistors


I’m definetly not a Rocket Appliance and I know shit from shinola about electronics, but here is my findings:

between any of the 6 solder pads marked in green there is continuity, but there is NO continuity between the green arrows and the red arrows… is one side the source, and the other the drain with the gate pad shown in red under the FET??


Scratch the above… looking at some direct FETs it would seem I’m on the mark regarding the Drain and the Gate, but the Source is under the FET as is the Gate…


well I made a thing and got it powered up…

with a 2amp smoke stopper fuse… hmmm the three red blinks of death

can’t we load vids up here?

Sorry, the file you are trying to upload is not authorized (authorized extensions: jpg, jpeg, png, gif, heic, heif).

anyway, I was able to get the BoxOfFoc into VESC tool…

uploaded FW5.01 still the three blinks of death…
hit RT data and got a DRV error…

the jedbox heat sink was very warmish … ~50C I dunno… but definitely warm, and a DRV error…

anyways the FocBox fits in the Jedbox shell, and the JedBox fits FocBox heat sink and almost the cover (except for the capacitor…)

so… I don’t know how much more time I want to invest in this errand of a fool…
The FET Source PCB must be carefully scraped to reveal the copper under… I need 2 new FETs and a new DRV…

how deep does this rabbit hole go?


Go deeper. For science!


funny you say that… I’ve just filled up a tall margi-on-the-rawks and i feel very sciency, and began carefully scraping away the esploded FETs to get to the “SOURCE” traces below…

you know it… i’m a sucker for science…
the FETs are like bux 4 each… and a gate driver dunno???

hmmmmm what’s making everything HOTish…

down the science rabbit hole I go…


I know sweet fuck-all about the inner workings of these things, but I believe that where there is a will there is a way. Keep drinking and sciencing :ok_hand:


I can send you a dead focbox you can pull FETs off of and possibly a working drv, it might be in better shape than that one…just shipping cost



you still have my addy Max?

lemme know what postage is and I’ll PayPal ya… I still have your PP addy…


$8, yep got your info, will get it out tomorrow


done… I’ll send ya the bux!


one thing I find surprising chiseling through all the esploded FET junk, considering the 8 “SOURCE” pads, is the lack of solder on the source traces…

The FET that exploded worst has negligible solder on the traces, the second FET shows very little solder… this can’t be right…


I wonder if the REALLY hard crap is actually the back of the FET solder pad that had committed nuclear winter sodomization their solder traces…

I’ll add words tomorrow…


Max, I received the FocBox… thanks brother!!!

any idea what’s wrong with her? I looked her over pretty good… She’s a 1.6, my first time comparing a 1.7 to a 1.6… there are a few subtleties!!

It would appear D101 south of the DirectFets is missing (scavenged for parts or bad?)

if you look at the piks above the traces for the “source” look pretty damaged… I “may” be able to get it to work, but I doubt I’d trust it anywhere near design amperage…

just wondering what the problem is with the 1.6 you sent me… I’d be easy peasy to source the Diode D101 from Fess’s broke dick 1.7, a lot easier than fucking with the fucked up traces on the 1.7…

even replacing the MCU and DRV chip look like a snap “comparatively speaking” vs. fucking about with those fucked up “Source” traces

what say you?


You might consider it a bit expensive but I’ll suggest it anyways. Get some circuit bond epoxy. It’ll allow you to hide away from shorts all the exposed copper in the solder mask. I believe you can get a kit (if you intend to science stuff more often) for around 130$ on


double fukkthat!