Mikrokopter Crashed

[Bartman]

I'd like to first say that I am probably the luckiest SOB in the world today. I could have crashed in the lake I was overflying on Saturday or I could have crashed from 400 ft up while taking pics of a house this morning but the multi-rotor gods smiled on me and took away my precious flow of electrons as I lifted off and was climbing through about 15 ft over some of the softest and thickest green grass that the great state of New Jersey has to offer a multi-rotor that is coming down in a hurry. I even got some power back which stopped my descent at the last second possible and left my camera and mount scared but not too broken.
I made the mistake of continuing to fly knowing I had an unknown audible alarm coming from my kopter. It's wasn't as loud as a low voltage warning but it was a slow steady beep. Anyone happen to know what that could have been? I thought it was maybe a GPS warning so I tried to fly anyway (BIG mistake, I know, I know! ) but it came down quick when it finally had had enough.
Looking at the boards nothing looks fried although the molex connector for the power dist board came off a little more easily than i would have liked. I thought I may have fried a Recom but they appear normal, I'll check them with a multimeter if that's possible this afternoon.
Thanks,
Bart

 

[Kilby]

Good luck! It sounds like you might have had a four leaf clover in your pocket, or was it the rabbits foot? That could have been total disaster, but I'm glad it wasn't.

Well, if you aren't wrecking once in a while, you aren't learning. ;-)

 

[Droider]

Does everything check out in the MKtool?

Hope nowts to badly busted

Dave

 

[Bartman]

I pulled the boards and nothing appears fried to the naked eye. I've applied battery power and the ESC's all initialize (chirp and flip the props) and have a green light. The FC board also has a steady green light and will initialize with the left stick forward/left trick. When I try to start the motors though I just get two beeps then nothing. I'm off to study the Wiki but if anyone knows anything about this I'd appreciate hearing about it.
Thanks,
Bart

 

[Droider]

Did you check the nav / compass plug?
Did you sort out the power surges?

 

[Bartman]

it wasn't so much a power surge as it was a very brief blip of power loss. I'm working to understand what the two beeps are when the motors fail to start with the stick back and to the right.
MKtool is next.
thanks,
bart

 

[Bartman]

un-freakin-believable! (translation: that's really unbelievable!)
MKTools shows a fault in the altitude sensor. Deselecting altitude control in Settings cleared the fault and allowed me to start the motors.
I've thought that my altitude hold didn't quite do its job ever since day one but I've just lived with it. Maybe I don't understand it but it's never been very good at staying at one altitude and I haven't been using Vario-alt-hold
I guess I have to order a new pressure sensor and plan to install it when it gets here. Until then I'm altitude-hold challenged.
Glad it's not something more complicated and that I got away with overflying the local reservoir this past Saturday without losing it into the water.
Thank you Multi-rotor gods wherever you are!
Bart

 

[Buzzed]

Never good to have a crash Bart but if it's gonna happen I hope it's always as minor (electronics damage wise) as the one you just had. With all the help you have here I'm sure you'll be back up and flying in no time.

 

[Crash]

Flux both sides of the board and reflow the solder on the baro sensor legs again.

un-freakin-believable! (translation: that's really unbelievable!)
MKTools shows a fault in the altitude sensor. Deselecting altitude control in Settings cleared the fault and allowed me to start the motors.
I've thought that my altitude hold didn't quite do its job ever since day one but I've just lived with it. Maybe I don't understand it but it's never been very good at staying at one altitude and I haven't been using Vario-alt-hold
I guess I have to order a new pressure sensor and plan to install it when it gets here. Until then I'm altitude-hold challenged.
Glad it's not something more complicated and that I got away with overflying the local reservoir this past Saturday without losing it into the water.
Thank you Multi-rotor gods wherever you are!
Bart

 

[Bartman]

Crash,
Thanks for the suggestion, should I remove it completely to do this? I'll try it tonight if I can stay awake long enough after the kids go to bed.
I just flew it again and it's perfect. With the altitude control disabled I can now climb and descend in GPS PH which is something I've never been able to do. I've always had to make do with a drunken altitude hold of some sort regardless of whether AH was activated or not. What a difference a little troubleshooting makes.
Thanks for the help, I really appreciate it. I just may have to concoct another little contest to let you all know how much I appreciate you.

 

[Crash]

On a V2.1 board, the 3 pins closest to the gyro are the only ones connected. The others are just support legs. The component through holes should be filled with solder as a matter of practice. The solder should leave a fillet on both sides of the board. It's especially important on the hole closest to the gyro because that one is connected to the baro by the through hole plating. So the answer is do whatever you have to in order to see the legs on the bottom of the board. I normally crank the iron up to 700f to get the job done fast. A little solder on the tip helps heat transfer. Don't forget the flux and clean the residue off afterwards.

BTW, Recently someone had a power problem. The through hole material at the lipo input failed. The fix was to solder the middle hole.

Crash,
Thanks for the suggestion, should I remove it completely to do this? I'll try it tonight if I can stay awake long enough after the kids go to bed.
I just flew it again and it's perfect. With the altitude control disabled I can now climb and descend in GPS PH which is something I've never been able to do. I've always had to make do with a drunken altitude hold of some sort regardless of whether AH was activated or not. What a difference a little troubleshooting makes.
Thanks for the help, I really appreciate it. I just may have to concoct another little contest to let you all know how much I appreciate you.

 

[Bartman]

Crash,
You're an asset to this site and to those of us that fly MK's. Thanks so much for the help.
Bart

 

[Crash]

You welcome and thanks.

I just realized that when you asked if you should remove it you probably meant the baro not the board. You shouldn't have to unless it has failed for real.

I just thought of a link to put on the distributors thread - chipquik.

 

[Bartman]

I just pulled my FC to see if anything obvious was wrong with the pressure sensor. Under magnification I was able to see that the right two legs are cracked. There is at least 1/8" of free space under the sensor so it's been vibrating away with every flight and the legs finally cracked. I would recommend everyone do an inspection and see if they have the same set-up (especially if they bought their boards ARF'd from Mikrokopter.us like I did). An easy fix would be to wedge the sensor up just a bit and shoot some hot glue under it, allow it to cool a smidge and let the sensor sit into the glue so it seats it.
Is it normal to have the sensor sitting up off the FC like that?

 

[Bartman]

I put a ball of hot glue under the sensor and I think I'm going to overlay some copper wire over the two cracked legs and solder it in place to avoid having to replace the whole sensor. Any opinions on that?
Thanks,
Bart

 

[RTRyder]

I put a ball of hot glue under the sensor and I think I'm going to overlay some copper wire over the two cracked legs and solder it in place to avoid having to replace the whole sensor. Any opinions on that?
Thanks,
Bart

I'd use something a bit stronger than copper, that can fracture easily from vibration as well. Go the local Radio Shack and pickup a cheap package of resistors, cut a piece of the wire off the end and use that, much stronger. The pressure sensor on my first MK F/C board has been mounted like yours is for over 800 minutes of flight time and its fine, you must have some serious vibration going on for it to crack like that or it was stressed from the beginning somehow.

Ken

 

[Bartman]

Ken,
I'm wondering too how it happened. Thanks for the tip on the resistor wire. I posted somewhere months ago that my altitude hold didn't quite work as advertised and that I couldn't climb from a hover in GPS PH. It's always been like that so I suspect the cracking started very early on.
Bart

 

[Droider]

Ken,
I'm wondering too how it happened. Thanks for the tip on the resistor wire. I posted somewhere months ago that my altitude hold didn't quite work as advertised and that I couldn't climb from a hover in GPS PH. It's always been like that so I suspect the cracking started very early on.
Bart

Bart.. its sounds to me that it must have been like that from the start

If a new sensor would be better than a fix, I'd go for the new sensor.. whats the cost of a new sensor against your MR?

OR is your roof leaking REALLY badly!

Dave

 

[RTRyder]

Bart.. its sounds to me that it must have been like that from the start

If a new sensor would be better than a fix, I'd go for the new sensor.. whats the cost of a new sensor against your MR?

OR is your roof leaking REALLY badly!

Dave

The sensors aren't that expensive, the bigger challenge is getting the existing one desoldered and removed without ripping out a pad or trace. Since its junk anyway if I were going to replace it I'd just snip all the legs and carefully remove them one by one by heating and gently pulling it up out of the hole once the solder is molten. It can be done but it takes patience and the more soldering experience you have the better.

Ken

 

[Bartman]

Ken,
I had thought of that as well, cutting the legs then just heating them up and slipping them out one by one. I already took delivery of a new sensor from digikey for about $15 so that's ready to go. If the sensor still functions though, overlaying a piece of wire over the crack is the sensible thing to do, IMHO, rather than remove and replace. I can always do that over the winter. Thanks again for the help, it's appreciated.
Bart