Faulty compass #2 (front) even after replacing it (ESC-board also new)

punkkone · Jan 3, 2020

Hi guys! So I bought a crashed MP, and boy was it crashed, chassi was broken in multiple places and lots of electrical damage.. Replaced pretty much everything except motor arms, GPS-board, ribbon cables and core board (it was shorted out and had physically burned the antenna diplexers to charcoal, had to bypass them and live without the wifi-functionality). I know a lot of people are borderline hostile when there is talk of tinkering with the insides of these drones and I'm starting to understand why as the lack of build quality is unsettling for a $800-ish piece of hardware...
Aaanyways, it was a fun project - the drone now flys just fine and I love it, actually my first drone ever

The issue I'm facing is that even with a brand new ESC-board (DJI stock part) it does not pick up the #2 compass at all (Compass disconnected, restart aircraft bla bla).
Compass #1 works fine.
Got a new compass #2 board, still the same issue.
I've tired re-soldering it (yes wires are correctly soldered on to the board), refreshing the firmware, factory reset etc. But to no avail.
The compass is getting voltage and ground.
I don't want to believe that the issue is with the ESC-board but I am unsure about how the hardware is integrated. The compass seems to be on a regular I²C bus but what happens between that and the main board? Or is is picking up the data from the ESC-board directly?
I there a good way of checking SDA and SCL (data and clock) without having a oscilloscope? (I'm a noob at electronics)
Am I going to have to buy another ESC-board and just hope for the best or is it likely that the compass I got was a dud?

Cheers!
Tom

punkkone · Jan 3, 2020

I should also add that the first compass board (the one that was in the wreck when I got it) had the cable torn off and I suspect it might have shorted out, so it wouldn't come as a surprise if that one is actually dead.

wattermelon1 · Jan 13, 2020

Just curious of you go this handled and if so what worked? I have a problem with the wifi ribbon cable connector came off of the board and am trying to determine if I should replace the whole motherboard (which I am told I will have to do because one little plastic piece broke off I have to replace the entire board. Thats messed up.

punkkone · Jan 14, 2020

wattermelon1 said:
Just curious of you go this handled and if so what worked? I have a problem with the wifi ribbon cable connector came off of the board and am trying to determine if I should replace the whole motherboard (which I am told I will have to do because one little plastic piece broke off I have to replace the entire board. Thats messed up.

Nah, I haven't got it sorted yet, but everything points to the brand new ESC-board being bad. Flying with single compass and crossing my fingers

As for the wifi ribbon cable connector.. That's unfortunate, but not catastrophic either, it can be replaced as long as the PCB leads have not been torn from the top layer altogether.
IF leads are ok there are basically two solutions to your problem, One is to replace the connector with a new one, I think it's a generic part. The other is having someone with a hot air station and a decent microscope taking a look at it. It would likely be possible to solder leads from the board directly onto the ribbon cable contact leads. (or the whole way to the wifi board if needed)