This is highly unfortunate, I’m assuming all of your phase wire connections were insulated?
sidenote - moving to mr60 on my newest build is a good move bc you can’t mess up wire order or have phase short
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they are bullet connected with heatshrink over the bullets.
really want to ditch work and open it up and inspect. WFH is a lot harder in these circumstances.
Bro I know, that’s why I’m in office (we had the option to wfh or be in office), so I can’t just go work on my board and have less distractions… oh wait
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I see no signs of phase wire issues at the connections and no signs of anything else blown except! …
it did blow a fuse. [ see them in the center on the board with the antispark.
one fuse goes to each vesc. naively swapping the bad fuse with the good fuse… poor detective work. it insta popped the good fuse on power on. so something is shorted somewhere. need to think about how to proceed here.
I will probably disconnect the motor now and do the checks to see if it still works.
Then maybe I extract the vesc open it up an inspect it’s insides?
photo, board is stock lacroix prototipo DSS50
vesc towards top of photo is what blue the fuse. which is middle top side of pic.
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I went riding tonight ok. I didn’t fix this thing. I hope this doesn’t make skatan mad.
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so the focbox is foc’d.
question is what caused it? what to do next so I don’t blow another one in it’s place?
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With the motor disconnected it spins smoothly. doing the hand tests of shorting phases together it seems to behave as expected.
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Plugging any two phase leads from the motor into any phase connectors on the focbox and they drag as if shorted.
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testing continuity on the phase connectors on the focbox shows two wires full continuity. between either of the first two and the third wire the other two seem to be charging a capacitor. current flows for a moment. then if i reverse the probes it flows again. on a spare focbox there’s none of this.
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The power leads to the focbox also are shorted / have continuity continuously. by contrast on a spare focbox. you get the filling a capacitor effect.
This suggests to me the focbox is foc’d
I think the hand tests of the motor suggest it wasn’t the issue. but how can I be sure? Next I will extract the focbox and open it up see what I can see… what should I see? how can I get to root cause so I don’t blow another one?
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Do those burn marks go all the way to the brass insert? Do they go even farther? It’s hard to tell. Is the mosfet split in half?
Damn. Is there burn marks on the brass insert?
Brass insert?
The brass circle on the top.
I’m supposed to be asleep. More later. :). Thx for looking / helping
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wish I could help, Fess, but I got nuttin’… and I need to go to bed…
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questions I’m pondering as a result of this mess.
Any reason not to run a 1.7 and 1.6 focbox together?
The original pair of focboxen were 1.7. I have a pair planned for another board that are 1.6 which i can steal to fix this board.
what’s the difference between 1.6 and 1.7 focbox?
is there an official reference? I haven’t found anything even casual in my searching yet. except maybe 1.7 is immune to the can bus burn out issue and 1.6 isn’t?
can I reuse the focbox 1.7 bottom case and thermal pad with a 1.6 replacement?
the thermal pad has burn marks on it. so … idk if I can clean that. apply some kind of thermal paste again? idk.
it’s a bunch more work to remove the aluminum plate and therefore all the electronics (see pics above). in order to get to the bolts holding the focbox bottom case in place.
trying to decide what to do there.
would a swap for a unity be an improvement?
If.i have to remove all the electronics to get the focbox bottom case off the aluminum plate well i can change anythign at that point and it’s my understanding the unity might have better thermal performance.
Why did this happen?
what else should I check before hooking up a replacement so I don’t just blow the replacement?
is this focbox repairable?
is this the type of thing people have repaired or is this thing junk?
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looks like focbox 1.6 will fit fine. in the same 1.7 case. I just need to learn how to deal with / replace the thermal pad and “properly” install it in the new base.
The internet seems to suggest you should never reuse a thermal pad.
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some ones been down this path before. and improved some things?
Generally you dont want to reuse a conformal materiallike thermal pads because its been formed once it often wont reform or make contact the same way again.
– https://www.reddit.com/r/buildapc/comments/bo5gin/reusing_thermal_pads/
someone saying don’t reuse a bit less firmly and with a reason.
my Jedbox thermal pads came out without marks, intentions, or any indication of use at the FETS
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