I have 2 Flipsky FSESCs like the one seen in this picture. A couple of days ago, one of them got disconnected during a ride and after re-connecting it to power, it won’t power on. No LED lights, nothing. I probed the 5V rail and I’m getting 5.1V, but when I probe the 3.3V rails, I’m getting 0V. The fact that I’m seeing 5V leads me to believe that the DRV8302 chip is working as it should be by stepping down my 6S pack(25.2V) voltage to 5V. The VREG (579-TC2117-3.3VDBTR) on the back of the FSESC, however, is heating up and I’m pretty sure it’s dead.
I assume that once I replace the VREG, it should power right up and things will work as expected. But, in the case that it doesn’t, I’m wondering if I should be keeping an eye out for any other components that could be causing the issue. Any help or insight is greatly appreciated.
Bonus question: Does anyone know why the act of an ESC disconnecting mid ride would have caused that?
Vesc based ESCs are known to kill themselves if they get disconnected from the battery during a ride and you try braking, because the regen current has nowhere to go.
I hadn’t even thought about that possibility! That would make sense, but how would the ESC know that I was trying to brake if power was disconnected? The CAN-BUS connector?
the capacitors, and braking current itself can keep the ESC allive. I don’t know how, but when my BMS switch was broken once I managed to roll down a hill on my board and still have brakes
Ah, that would explain it. I mapped the ride with the “Yours Truly” App on iOS and it shows that my second ESC lost power/died right around an area where I would be braking. Quite the bummer. Did you ever end up killing a VESC based ESC like this? If so, did you attempt to repair it?
Fortunately I have not; there are some guys on this forum like @seaborder and @JohnnyMeduse who repair ESCs and might be able to tell you more, but with something as cheap as a flipsky 4.12 that are known to kill themselves anyway, I don’t think there’s much point in attempting a repair.
@prime Meassure the resistance between 3.3V(VCC) and GND.
Regulator could be getting warm from a short(cant supply the current), or like you said, its busted.
Thers a big chance your MCU is borked as well.
If you have a short when meassuring, remove the 3.3V regulator and hope to the gods the short is gone. If its still there, next step is to check if short is gone when removing the MCU.
If short is not present when regulator gone, you can try to patch in 3.3V from a lab supply to see if the LEDs start blinking. If they do you’ll prob be fine only replacing the regulator
There’s a short between ground and 3.3V, but I haven’t removed the VREG yet. I’m waiting on my hot air reflow station to arrive. Fingers crossed the short goes away when I remove the VREG! I’ll be sure to report back when I learn more.
Thanks for all of your insight @linsus, you’ve been extremely helpful! Thanks @rusins@EreTroN for looping folks on this thread, you guys rock!
@linsus regrettably, there is still a short between 3.3V and GND after removing the VREG. The hot air reflow station still hasn’t come in yet, but once it does, I’m going to remove the MCU.
@linsus bummer, I finally got my reflow station and I removed the MCU, made sure all the solder pads are clean and clear, but the short is still there between 3.3V and GND. Any other recommendations?
At this point I’m thinking I’m just going to put 5V @.25A to the FSESC and see if I can measure a voltage drop across a bad component, but then again, I was thinking maybe the DRV8032 may be my root cause. Any ideas or tips and tricks are extremely appreciated!
The CANBUS chip (SN65HVD232DR) let the smoke out and failed short. If you look at the picture, you’ll notice that there’s a tiny spec on the “3” in the 232 on the IC. That is where it let the smoke out. It never raised any red flags during my visual inspection, but running my fingernail over it to try to remove it, let me know it was raised up and felt like a bump on the chip.
Here’s what I learned:
There are only a few ICs on the FSESC or any VESC based ESC that interact with the 3.3V power rails: (STM32F4 MCU, 3.3VREG, the CANBUS Transceiver)
ICs are likely the culprits, so check those first, and be sure to check for tiny specs where they may have let the smoke out. The next likely suspects would be any semiconductors like diodes. Lastly, check passive components like resistors, capacitors, etc.
I knew very little about troubleshooting or fixing a circuit before I started, but I feel comfortable diving in head first now. There are only so many failure points, you’re bound to find the problem component.
My work isn’t done yet. I still need to make sure none of diodes, caps, or resistors are dead and failed open instead of having failed short. Most importantly, I need to solder a new MCU, CANBUS Transceiver, and 3.3VREG back to the circuit and pray that I’m able to flash a bootloader to the new blank MCU chip.
Shout out to @linsus for the tips along the way. I would have never started removing ICs had you not called that out!
I just installed/soldered a new CAN-bus chip and 3.3VREG chip. I need to install and reflow the MCU. Once I do that, I’ll let you know if things are working again.
