Focbox: Did I kill both in 1ms? HELP

Apparently so. Since you did not get 3V3 out, and CAN chip is bad, desolder the CAN chip and see if the FOCBox wakes up. If it doesn’t, measure the C25 and if it still doesn’t have the 3,3V, i would suspect the regulator(GH12E).

How powerful board are you going to make? Even one anti-spark circuit with one FET is enough for normal commuting.

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  • 10s4p Sanyo 20700B
  • Street-Wing Motors 6374 / 190KV

I wanted to secure each Focbox with an 40A Fuse and those Anti-Spark Switches got 40A fuses inside - so I installed both.

Now I am a lot “smarter” - thanks to @JohnnyMeduse and @Quezacotl.

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Is the TVS diode this one?

Looks like a SMCG51A


I was joking with a friend via WhatsApp and ask him if he got some of those CAN chip around. He sad no, I only got the newer version and then he gave me 10 of those:

Could I use them?

I am just curious how did CAN chip died then it has protections?

you can always try them.

there is no protection, it is a design flaw that is present on every vesc or derivate on the market, except the 6 (since it is a different can chip)

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What about this

Designed for operation in especially harsh environments, these devices feature cross wire protection, loss of ground and overvoltage protection, overtemperature protection, as well as wide common mode range of operation.

Oh well maybe just shitty chip… I usually use the ones with isolation…

NOPE, not a shitty chip, Ground loop problem…

I just don’t see what you trying to prove here

I am not trying to prove anything I am just curious… That’s all, I have been working, with multiple CAN systems, and never run into the problem with ground loops…

I am just trying to understand how that happened so that I could prevent this kind of cases in the future.

First off that TVS diode with the white gunk on it is not blown, my brand new FOCBOX’s have it as well. Also why where you using two switches instead of just one connected to both FOCBOX’s? And I wouldn’t try using that different CAN chip unless it states it’s a drop in replacement and all the pins are the same.

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I think he had two switches so he could pull 80a (40a each switch)

You could wire the on/off switch in parallel to both antispark-switches like @esk8 did it. I don’t know if it’s necessary because the 40A fuse can take more than 40A for a short period of time, for example 60A for 10 seconds and even more for bursts. Also I don’t know what happens if you use 2 switches and only one fuse blows (or one switch dies), maybe you could harm the second FOCBOX as well. I had a single switch running on my MTB and the 40A fuse never got blown.

I would use 1 antispark-switch only and if you want a bigger fuse then you can desolder the fuse holder of the antispark and solder a bigger fuse like the one in the picture. 150A is too much but they are available in 80A. too.

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Why only 40a focboxes can handle much more

Thanks Rich, I had the same thought last night. What if I take two Anti-Sparks and one blows - it will automatically kill my other v4 “x-VESC”.

Now I am heading into the office and try to de-solder that crapy CAN chip.

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There are anti-spark switches being sold that are capable of handling 80a or more/it’s not just the fuse that is different.

Two anti-spark switches and canbus may again lead to trouble in the future. Would opt for two receivers with disconnected canbus.

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Guys, I just came into my office and had a stupid idea while I saw that heat gun laying on my desk.

I grab a tong that grabbed that CAN chip and lifted the whole PCB 5cm. Pointed the heat gun at it and 5 sec later GRAVITY kicked in!


There goes the warranty :stuck_out_tongue: good work


JohnnyMeduse Fixed mine. Just send him pics of the inside of your foc box and he will let you know if he can fix them. It’s a bummer I fried mine as well.

OK - I tried but they dont talk - I suppose the MCP2551 does need more than 3.3v as the sn65hvd232 does.

Ordered 10 of the SN65HVD232.

So project does need to wait until 2018…

Thanks for all the help from @JohnnyMeduse @Quezacotl @Kug3lis

Today, by mistake I connected each esc 5s apart and nothing burned same CAN and etc used…