Focbox: Did I kill both in 1ms? HELP

ESK8 Electronics
1

Hey guys,

I am in a kind of shock since yesterday night. Was finalizing the beta of my build - getting the electronics to fit into a plastic box.

It was all working - I did not like those bullet motor cables - so I put some shrink tube on them to be save. Fitted the Focboxes inside and came to that idea that I could use those two Vedder Anti-Spark switches just in front of each box.

But it looks like one of those Anti-Spark Switches got its power-switch attached wrong - so it was ON instead of beeing off.

It was late - and it looks like I did connected all stuff from the battery side - as doing it normaly from the electronics and do attach the battery at last.

There was a little spark inside of the XT60 connector from the Anti-Spark to the Focbox.

But than only the red light of the 2.4gHz receiver started to light up. Not one of the Focboxes LEDs came up anymore.

Here you see the step of applying the shrink tube.

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Here you see it with the finished shrink tube.

Google Photos

Here you see only the 2.4gHz receiver beeing powered - focbox shows no lights. I disconnected everything not needed to extract possible failures.

Google Photos

So I opened one focbox - here are the pictures - But I dont see anythink blown up - nor does it smell burned.

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Backside - only that white on the chip in the middle of the caps on the right - seems strange.

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Does some of the VESC gods do know whats going on? Can I fix the focboxes somehow?

2

@scepterr This might seem like a situation that I’ve been through before

4

Im not expert by any means but that chip kinda looks fried

5

Just opened the second focbox

7606EBDA-10FE-42F7-8C7E-6326990BE2A0.jpeg2050Ă—1536 511 KB

6

Yea they kinda look a bit burnt to me

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7

It looks like a white powder from colombia spread all over that chip.

What is that chip? Name? Numbers?

8

It’s diode I think, and I think you reversed polarity…

2 Likes
9

I guess the diode protected your whole board, so you just need to replace it :wink:

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10

I just un-installed on box.

GFZ 74A

is written on it.

seems to be a z-diode?

Great - but where to get this “thing” in Hamburg in the next 3 hours, and find an SMD soldering pro.

11

Do got an idea - what kind of spec’s of this diode I should look for?

12

Hmm, I can see the number in schematics

image.png1077Ă—625 55.1 KB

But its zener diode… Hmm, It should be transient voltage zener diode…

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13

Maybe this, don’t know because can’t find correct marking on datasheets

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14

I think technically it shouldn’t make the focbox to not work… Maybe you can try to remove it.

I am not pro at this field so I cant help much with TVS

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15

you mean remove it and short the connection?

16

Just remove do not shorten

17

and leave those two solder points open after removing?

18

Yeah, but I can’t guarantee it will make a change, because from logic it shouldn’t make a change… Maybe something else is also burned… But not visible

1 Like
19

Have you even measured any voltages? To see in what point it stops…

20

Great Question!

I am a software guy - have no f**cing clue - where to put the multi-meter to find out. At least that 2.4gHz receiver and the bluetooth module got power.

21

Measure if there is battery voltage on both side of the diode in question. Measure if there is about 3,3V and 5V between any three legs on the GH12E(on backside of board) Measure also all other same looking diodes if they got about 0,2V - 0,7V.

1 Like