Cleaning up solder joints on VESC's DRV8302

[RideTheIon]

Last year I got a pair of VESCs. I had them wired up, bench tested and all, then winter came.
I thought that all I had left to do was run the motor detect with a free spinning motor and stick the case to my board.
Well, loaded up then newest BLDC tool and it said to load a newer firmware. Somehow “hw_410_411_412” seem like a good candidate so I loaded it up.
Few hour later I notice that both the controller’s DRV8302 are blow or at least that’s what the BLDC tool terminal is telling me

I'm not 100% sure that the VESCs were working fully before loading the wrong firmware. I had bench tested it with a lab power supply while the motors were linked to the wheels. The control was kind of on-or-off, but now I can only get the motors to twitch.
I only recently found out that I can query the fault codes, so the fault might have been present before.

I order new DRV8302 chips, but I thought I'd try to see if the problem might be a solder bridge, cold joint or something.
If someone’s going to remove the chips anyhow, as long as I don't hurt the traces, I can't break it more than it is now.



Based on How To Solder Your Own VESC!, pins 4-5 and 6-7 can be bridged and it doesn’t matter.
Anyway I'd like to try and clean up the smaller solder joints before sending the boards somewhere to have the chips changed.
I have a small bottle of flux and copper wick. I can borrow an adjustable temp soldering iron and heat gun.
Has anyone here fixed up a SMD board by hand? Can I apply the method that I try to soak up as much solder as possible, then put on a fresh layer?
If I work on ¼ of the chip at a time, it won't shift out of place, I guess.

Here's a pic of my case.
I'm probably going to have heat problems, since the air can't circulate inside the case, but at least it's something to get started with.

 

[WeeChumlee]

Hi
There are a good few posts here and on Vedders Forum about loading the incorrect firmware.
I am no guru here but I believe there was a change between V4.7 and V4.10 and loading incorrect firmware can cause the Driver chip to pop.
If you state exactly which board you have then someone with more knowledge on than VESC than myself could tell you which firmware you can use.

If you are going to try solder a new chip in yourself then I presume you have limited tools?
What I have done it the past with such chips is to first cut the chip from the legs, I use a very fine nosed cutting tool but have also used a scalpel. (Then pick up the individual legs with the soldering iron)
This usually does not damage the PCB or pads to much. Trying to desolder the legs still attached to the chip often leads to pulling the pads off the PCB.
I personally do not use a heat gun, many do and it can work very well.
When placing the new chip I do not take as much initial care to bridges between pins, more care all is straight and pins are centered on the pads. Once that is done I use solder wick to clean up and remove bridges.
(There are of course many ways and tricks to do these things)

Anyway, I hope you get it sorted mate.

 

[RideTheIon]

I bought the VESCs from jamesonotc from his September 2015 batch.
I'm not sure about the HW version. I sent jamesonotc a msg a week ago, but he's probably still in winter hibernation mode.

The board is probably hw_46_47 or hw_48 at best.
When I was loading the firmware, I had a brain short and though that hw_410 meant maybe 4.1.0 which doesn't make any sense since then hw_46 would have been hw_460.

If only one of the VESC was malfunctioning, then maybe it could be a short or flux conduction ect, but it looks like it is wishful thinking that I'll be able to magically fix the boards without changing the chip.
I looked at the soldering and except for the pins that are anyway bridged at the PCB level, the work looks clean.
I'll try to clean it with acetone and a small sponge then pull a fine needle through the pin gaps.
After that my only options are to send it out to be repaired or join the local hacklab and learn SMD repair. There I would at least have the right tools.

 

[Trbt555]

The hw version should be written on the pcb somewhere.

 

[RideTheIon]

Thanks, but unfortunately the PCBs these VESC are built on don’t have any printed graphics.

It would have been cool in this situation if it had the HW version, but otherwise, since this wasn’t a solder yourself project, it is useless to print the “frames” for the components and connectors.
Maybe it makes repair easier when you don’t have to reference a schematic to find e.g. capacitor C23.

Google picture search show a few VESC PCBs with “VESC 4.6” and “VESC 4.7” printed next to the ARM processor. So that’s probably the place where it should be printed.