Pixhawk compass problem (with both?)

Hello! I’ve been an hexacopter APM user for about one year, love arducopter it and never had major problems with it. Well, 3 months ago I purchased a Pixhawk from here. At that time I wasn’t aware there were legit and clone boards. So this one probably is a clone board, despite similarity.

I have this Ublox NEO M8N working with it and it is great, I can get arroud 17 satellites and HDOP around 1.

At the first day, I had problems to get compass working. I couldn’t get it to point to the real north. Then, in the next day I calibrated it again and it worked on first try.

But lately I realized compass has been performing some strange behaviours again. Not only it points to anywhere but north but sometimes it keeps slowly turning arround by itself. I don’t think this is magnetic field issue since I’ve seen this happening in different places (and away from electronics). And there’s no calibration that solves it. Also I get many warnings on Mission Planner like “Error Compass Variation” (most of times), “Bad Compass Health” and sometimes “BAD AHRS”.

Sometimes compass works well, mostly when I leave it alone for a while. But after a reboot or two it gets strange again.

Today I went to do some flight test and from OSD I could see compass was right. On RTL it came to the right direction, but loiter had a strange behaviour of doing some dangerous circles around it’s position (keeping heading) until it stablized on it’s position. This also made RLT not so stable.

From what I could understand, Pixhawk has it’s own compass and so has that GPS module. Assuming one of them is faulty, I could’d not make pixhawk use only one or another, because even picking Compass1 or Compass2 on Mission Planner it behaves the same. Am I unlucky enough that both are damaged?

On QGroundControl, after every calibration it tells me Compass1 and Compass2 have poor values.

This is what my build looks like (partially disassembled):

Can anybody point me some possible solution, considering I can’t replace pixhawk anymore? Could this be solved by software, or maybe replacing gps module? I can provide flight logs if needed.

Thank you very much!

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