3DR + APM2 - 5 days on the bottom of the sea, the result:

Because of inverted compass, as described in another thread, my 3DR + brand new APM2 went down, and it took 5 days to get a SCUBA diver to get it (I sold my SCUBA equipment a while year ago)

I memorised the position where it went down by observing the background and the fence, so I could guide the diver from land to the right spot.

Treatment:

-submerged in fresh water.

-gently dried off with towel.

-GPS shield and metal shield over switchmode 5v regulator desoldered.

-slowly baked with increasing temperature to 70degree for 2 hrs.

-Then everything got 10 minutes in ultrasonic bath filled with acetone.

-baked slowly up to 70 degrees.

-cool down

- all gold plated pin headers got deposits wiped off on each side, all look good.

testing.

My APM2 is now rusted will never be reliable: (before ultrasonic bath.)

Status:
Frame, ok
1 prop broken on impact.
prop adapters and not shiny anymore - interesting how they corroded.
Motors; ball bearing certainly die soon. Otherwise, I guess the wet part of the cables can be cut away, and they can work for testing - not reliable ?
Power distribution board; very corroded, can be made usable.

DEAN connectors, certainly not gold covered, destroyed. Some female DEAn connectors most damaged.

EC3 battery connector; connector surfaces good as new (gold plated), some corrosion on the soldered end.

-3A 5V Switch mode regulator ; (with the metal cover off) - little corrosion, works fine.

-Bluetooth module - works fine

-ESC's (4x Turnigy plush) - all burned, logic starts, but FETS are burned.

-Graupner HoTT GR16 , RX/TX, works fine, very little corrosion, lost one antenna, will be reattached, and then tasted for range. - looks very good.

-Micro SD Card, never worked, (did not got any reply on this from support) it looks very good.

-APM2 looks awful - -The small plastic connectors are not gold plated, and are destroyed.

- I will now bake the working parts again for moisture - then cover in acrylic

Will test APM2 - to see it it can be used for unimportant testing - as it will never be a fully reliable APM again.

Still hoping that DIY will warn all users of this dangerous Compass reversal problem.

They did not bother to do so when I mailed them right after analysing the crash - nor did I ever got any resonse to the uSD card that never appears as inserted.

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The diver + the quad.

badass image btw... : D

first sorry for your lost of hard work and money.

maybe you would want to consider anti water covering

such as that.

Yes, but Neverwet, last time I checked, isn't commercially available, it's just a site with some boasting, probably needing some of the more diffictly application techniques, like vapor in vacuum as multiple vendors use.

While I use some traditional conformal coatings in my more expensive drones., this was just a testing platform, - still - I did not expect it to self-destruct like this :)

- nor did I expect the forum admins to censor my warning about this bug when I posted it with a subject that went straight to the point.

when I think of it, DIY's handling of this problem (or lack of it) - and the fact that I never got an answer - scares me.

lol, didn't expect you to post on this too. 

OK. I get the attitude.

Regarding "what I am doing" - having much experience with this and similar hardware, flying with *much* more expensive stuff than this - often over water (living on a island) - I would say I know what I am doing.

Having "luck" enough to calibrate compass correctly after pressing reset, does *not* qualify an "not knowing what I am doing" because there a huge design fail/bug that reverses compass !

A huge, dangerous bug should be admitted, not covered up or buried with the "you don't know what you are doing"  pile.

This was first flight, with well tested config of APM1. There were no reason to "guess" there was a huge, dangerous design error/bug that would invert compass.

It's not like it got to fly with my most expensive payloads, it's just a simple test. Still - this looks most like a design error (too short reset on boot for magnetometer ? ) - and there's NO reason/excuse for not to warn whole community against it.

It's ok, I'm sure if they had it would have gone something like "you should have known better, you should have bought better radio gear, you should have tested better, it's open source better luck next time, we only make hardware its your fault, geo fence it, if your not an rc expert with esp maybe you shouldn't be building quads, etc, etc."
Apparently it's our faults and we should just instinctively know things that aren't documented very well if at all with regards to the operation of our crafts. Oh, and its our fault if the docs aren't complete, accurate, or don't contain the necessary warnings.  o_O
Sorry, just went through similar:http://www.diydrones.com/forum/topics/my-4-day-experience-w-ardu-3d...

First of all, nice pictures, fantastic (sad) story. 

now to the point. NOT trying to stir up the conflict again but I would like to know what you reported for the compass bug. 

Maybe just change the tone, make it informal and not pointing finger at design flaws.  Just put the facts, what you did and what it caused, no need to get into a flame war again.  I did not see your warning post and I can't comment on why it was removed but for sure if the tone is aggressive it will not work. 

We are all passionate people around here and it's easy to get overwhelmed.  So please straight to the point, informal and not judgmental.  If you did a sequence of events and actions that lead to inverting the compass we need to know, record it as a bug and get someone working on it. 

In the past 2 years there were a lot of things reported that were bad, people lost a lot of parts (I sure did) but it's the risk of the hobby we have.  I often reported issues and I never got censored.  Keep it polite and it will be fine.   Zen, I dont want to re-open your own debate, we all know now about it. 

Please let's just document the compass reversal thing shall we? 

Dany

  

 

Please note, that even I did much to resurrect the APM2 - the compass and SD never worked, and still won't - I verified the PCB traces on the mainboard and the shield - not finding any error.

Another APM2 works - and work fine, with the same setup - yet I did not care to rebuild that quad yet, as the "fighting wind over time throws off AHI" is still a problem. (and the reason I could not make it level off with AP disengaged.)

So - the APM2 that sunk, have most likely been faulty from the factory, and lost magnetometer in flight, -OR- it booted without it.

I confirm that much of the "reversing" I described in another thread, is the fact that it booted and assumed "north" direction without mag. - which is conveniently south, due to the direction of my workbench. - At least that's the issue every time after the drowning.

If I expect that something is learned from this - it's that APM should not arm unless real compass is detected.

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