Vesc repair (dv6)

I figured I’d start a separate thread instead of continuing to post in the dv6 thread.

Well it seems electronics and I don’t mix, I’ve screwed up something else, you’d think I’d learn after having to replace my kweld from a short.

I seem to have shorted my dv6, I thought I was good, it’s in its own case, I had the vx1 receiver on one side of the enclosure and the antispark on the other, the dv6 in the middle, the way I had the wires run it was tight and I thought I was good keeping components separate and snug, I didn’t tape anything down for the test run, which was my mistake I think, but I’m not 100% sure that was the fault.

Well I went for my first ride on the mountain board after finally getting it together, got speed wobbles, laid it down,just kinda slid a bit, nothing crazy, and after something wasn’t working, one side of my dv6 was dead, no power at all. And also my flipsky Antispark was no longer functional, staying on.

So long story short, I don’t see any obvious bad components, here’s my short circuits on the dv6


These pins are all shorted together on the comm port

And these two pins on the voltage regulator

Could anyone point me in the direction of where to check shorts? I assume lifting the voltage regulator would allow me to check and make sure that isn’t the culprit and if I still have a short on the circuit board then I need to go further, if it’s not a fried voltage regulator then is the problem a shorted stm32 chip or does that go toward the drv next?

Does it power up at all?
Do you have a bench supply so you can see the current draw?
Meassure between GND->3.3V and GND->5V. You can do it on the connector.

Usually its either the regulator or the MCU that has given up.

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Do you mean bench power supply? I have an 18v 18amp bench power supply, would that work?

What am I measuring across those pins? Voltage when the vesc is powered with the 12s battery? Would I get voltage at if it was shorted across those pins? Or your saying Set the voltage to 5v and connect to those pins and see what amps the bench supply is reading?

Sorry I’m completely uneducated in the ways of circuits, but I think I can pull of replacing the regulator and stm32 chip as I work under a microscope with small tools all day, my soldering skills are pretty decent as well.

As far as power up, I get no lights on, and the vesc tool will not see it either through can or if I plug directly into that side of the dv6, the other side of the dv6 functions correctly.

Also since the tx rx pins are shorted I was leaning away from it being the regulator no?

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Also, I may be incorrect, but if I understand it, if I replace the MCU and no more short, and everything powers up correctly then I just need to flash the bootloader and then the firmware and it should function correctly?

Yes, if your supply can display current draw and preferably also has over current protection then you can find out what its drawing.

Generally when hunting shorts you’re measuring Ohms. Doesn’t need to be powered for this. Check resistance between GND and the supply pins. If around kOhm or greater, then you can turn the vesc on and check if you have both 3.3V and 5V present on the same spots.

Yeah, pretty much

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Here is how I’d diagnose it, starting with the quick stuff:

LEDs

  • Blue LED shows the presence of 5v. No blue LED means there is probably a short in the 5v rail, or just an absence of 5v all together.
  • Green LED (or red on some Unity/Xenith ESCs) is turned on by the firmware, so it shows that the 3.3v circuit is working, and the firmware loaded.

Power Stage

  • Unplugging the ESC from everything
  • Put multimeter in resistance mode
  • Test resistance between all the phases. Looking for consistency in the 60-140kOhm range. All should be roughly the same +/-2 kOhms or so. A low or high value points to a shorted mosfet.

Logic Stage

On DRV based designs, the battery voltage enters the DRVs directly, and is then converted to 5v. That 5v then goes into a 5v to 3.3v regulator to power the 3.3v stuff like the STM32 and canbus chips. The idea here is to check each of those systems as it will narrow down which chip may be faulty/shorted.

  • Unplugging the ESC from everything
  • Put multimeter in resistance mode
  • Measure from a 5v pin on the comm port to ground. Should be in the kOhm or MOhm range. A low value means that some component on the 5v rail is shorted. This is fairly uncommon. A shorted value here is most likely a DRV or voltage regulator.
  • Measure from 3.3v pin on either the SWD port or comm port to ground. Should also be in the high kOhm/MOhm range. If it’s around 1-2 ohms, it’s usually a shorted STM32, but can also be a shorted canbus or vreg.

Three methods to narrow it down further:

  • Replace all 3 chips
  • Remove one chip at a time until the short goes away
  • Inject 3.3v to that rail using a bench power supply limited to 100mA or so. Use a thermal camera to see which chip is getting hot. Increase slowly up to 500mA-1A if nothing is showing up on the camera. Replace the hottest chip.

If the STM32 needs to be replaced, you will need to use an ST-LINK V2 (clones off Amazon are fine) to manually load the firmware onto the new blank chip. The firmware .bin file can be found on Vedder’s firmware archive on Github. For the DV6 you’d need to use hardware “60”, or you can use the firmware from MakerX’s website as I think some upgraded version of the DV6 had an on/off switch that needed a different hardware config. Would be nice if MakerX would actively contribute that stuff back to the main VESC project. Flash using the default address of 0x08000000. Once the firmware is loaded, you can open it in the VESC tool and flash the bootloader. Bootloader is only necessary for upgrades.

Replacing the chips pretty much requires a microscope, temperature controlled hot air station, soldering iron, good flux, solder wick, and quality solder. I’ve seen some YouTube videos using solder paste, but I find that to be harder and somewhat pointless on rework stuff. Plus that stuff has a fairly short shelf life. Instead look to older Louis Rossmann repair videos or NorthridgeFix on YouTube to see how they replace similar chips. The steps are generally:

  • Protect stuff that can melt like JST connectors or electrolytic capacitor covers.
  • Remove any heatsinks
  • Add flux (I like the AMTECH VS-213-A-TF)
  • Hot air to remove. Try to start farther away and bring closer, to somewhat follow a typical soldering reflow curve.
  • Solder wick to clean up old solder with soldering iron
  • Tin the pads with new solder
  • Add flux
  • Place chip roughly in position. Doesn’t matter if it’s not perfect.
  • Hot air to reflow into place. The chip will kind of “snap” into place once all the solder is melted. Lightly press down on it, remove the hot air and let it cool.
  • Clean up with isopropyl alcohol and test.

Simple testing

Plug into a 10Aish power supply and run a motor detection and see if you get reasonable results.

If that passes try a load test. Add the heatsinks back on and run foc_openloop. This can only be run from the desktop tool AFAIK. Make sure the heartbeat is on, turn on RT data, and run something like “foc_openloop 80 1000”. This is 80A at 1,000 eRPMs. Let it run until it thermal throttles. Needs an input of about 10A at 30v. Best if using a lab bench power supply or even a decent charger vs a battery. If something does fail it generally won’t blow a hole in the PCB like a battery can, which can supply over 1000A when shorted. Just don’t use regen or stop the motor with throttle when using one of these as the voltage will spike in the controller/power supply.

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Wow thank you, that’s pretty in depth, a great write up for any future vesc repair searchers, I will poke at the diagnostics because I like to understand how things work, but I think I’ll leave the repair to @jaykup who has quoted me a great price for his service today.

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Got damn thats a wall of text. Good effort :pinched_fingers:t3:

TLDR;(not sure if jay mentioned this) if your esc has a antispark and its broken, powering up might not work at all and the vesc could be healthy. Then you need to bypass the switch to diagnose

Good stuff.