Another blow Focbox, help with diagnosis

I thought these things were more robust but it seems they are not.

I bought 4 Focboxes for my Trampa, 2 for immediate use and the other two for spares.

Right off the box, the first Focbox threw an overcurrent fault when I pulled the trigger at full throttle, the scary part was during the error the Focbox kept the board at full speed, no response from the remote for 3 seconds, pretty scary feeling. That VESC is already back to Enertiin fir warranty.

The second Focbox died on me while braking 4 days ago, only one wheel was spinning slowly on full throttle. The bad VESC wheel had resistance if I turn it by hand, so I unplugged each of the three phase cables one by one, when unplugging the center phase cable the motor was released and it brake when I plugged back in.

Can anyone help me finding the culprit of the second VESC issue?

Does it power on? Get any faults in bldc tool?

Yes it powers on but there are no signs of blown electronics.

Tomorrow I’ll look for errors on bldc tool

Opened it up?

Yes I’ll upload pictures tomorrow as well.

Thanks for replying!

Are these the new Focboxes from China with the 14 awg phase wires and 3.5mm bullets. Also can you please share the specifics of the setup and bldc settings?

They come from china now? Didn’t the US version also come with that wire and connectors? I don’t think they ever had a different configuration.

@Eboosted doesn’t a short like that mean a Mosfet failed? If so you might be able to fix it yourself as they are easier to replace than a DRV.

Edit: ah well they are directFETs - so probably not easier to do by hand :frowning:

Mine is, got it a little over a month ago

@Maxid DRV takes 10 minutes to replace with a cigarette break in the middle :grin:

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These are the ones, why do you ask?

If you have a reflow oven - with just the standard tools it is trickier

Those are the old vescx, what’s the hw version on the PCB?

I don’t use ovens, just hot air station and IR board heater

Then you have good soldering skills and a steady hand - where are you from exactly :wink:

NYC, I run a repair shop, after replacing 1000s of iPhone logic board ICs, anything on the vesc I can do half asleep lol Sadly I got the focbox thinking it had some magic sauce that made it worth the premium and I thought I could rely on the warranty. After mine took a dirt nap and I diagnosed and repaired it myself I realized I shouldve just made one myself :confused:


I can relate to that, After 40+ years of welding and the last 20 years welding SS pipe, I can almost do it half asleep.

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If the 3.3v pin is shorted with the GND pin then you’ve blown the canbus transceiver. Just use a multimeter to check this. You can blow that part when you are using two vesc-x/focboxes connected by canbus and power them on/off one by one. To avoid this you must power both vesc-x/focboxes on at the same time. I highly suggest that you make a cable to connect the two in parallel.

To repair this you’ll need to replace the canbus transceiver.

The P/N is SN65HVD232DR and I ordered my replacements from mouser.

I used an “smd rework station” to replace the chip.

After replacing the part you should be good to go. It’s a pretty tricky repair job to do it correctly, and it’s really easy to fuck your boards up and make them completely unrepairable.

Wouldn’t something like this be easier for the CAN chip?

Hot air station is best, a regular soldering iron will work just fine too. Those tweezers are not for smd work. If you really want tweezers then these

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I have a short on 3.3V line on my maytech vesc. And I do have smd rework station but never used it. Do you think by watching few YouTube videos I should be able to preform procedure myself ? Im kind of scared haha.