Couple Newbie Questions / Observations from my DJI F550

[plasticjoe]

I just resoldered all 18 bullet connectors tonight... mercy I hope that solves the issue !! I'll test it tomorrow

 

[plasticjoe]

OK... all the connectors resoldered... and the Beast still flipped 2 more times in less than 10 flights...
broke 4 props in 2 flips... and each time it's flipped is AFTER I flew it at least one flight... so no... motors aren't running backwardS. It's on level ground... and the esc initialization tones sounded like they always sound.

and when it's on it's back running... it's running longer than the 3 seconds before it's supposed to kick off. I don't have any other Naza'a to test it with... this is my first multi-rotor

I guess I'll contact DJI and see if they have seen this issue.

 

[Chalagi]

I think its your naza thats giving you all the trouble. If your heli is new send the naza back to the dealer and have then to check it out.

 

[Dale UK]

I had exactly this issue with my 'stock' F450. Mine turned out to be - I cable tied the ESC's to the DJI arms too tight (put the cable ties around the middle of the ESC and round the arms. This slightly bowed one of the ECS's which have under the heatshrink cover a metal heatsink plate. Because of the overtightened cable tie it had caused the plate to short on one of the board components - but only occasionally and randomly!!

Now I cable tie the wires at both ends of the ESC's through the crisscross of the arms and pull a small 1.5mm tie lightly over the ESC's and arms (I'ne seen elastic bands used to secure ESC's which is probably good).

Hope this helps??

Dale

 

[Dale UK]

Did it do something like this? ..................

http://www.youtube.com/watch?v=1HsohMXTE2A&feature=youtu.be

 

[plasticjoe]

every time it's flipped was on the ground... never in the air, but pretty much the same way... just a fast flip..... not every time though. The ESC's are zip tied in the middle of the unit... I'll move those tomorrow

 

[plasticjoe]

How were you able to identify the "offending" esc ?

 

[jforkner]

I had exactly this issue with my 'stock' F450. Mine turned out to be - I cable tied the ESC's to the DJI arms too tight (put the cable ties around the middle of the ESC and round the arms. This slightly bowed one of the ECS's which have under the heatshrink cover a metal heatsink plate. Because of the overtightened cable tie it had caused the plate to short on one of the board components - but only occasionally and randomly!!

Dale

You may have just solved a similar problem I'm having.

How did you verify that the ESC was shorting, or did you just assume because the problem want away after removing the cable tie?


Jack

 

[kloner]

joe, is there many wires touching the naza, like on the side, top, etc?

 

[Dale UK]

If you watch the flip, I'll bet it flips the same way each time ie clockwise or anticlockwise and will also as its flipping go forwards or backwards at the same time - like you operated the elevator control on your transmitter. The way the system works it is unlikely that ONE of the motors will suddenly 'speed up' - much more likely ONE of the motors 'dies' for a short second. This is what induces the flip. So - if you establish which way it keeps flipping - then imagine that the motor that will in theory hit the floor first by the direction your Quad flips is the one with the fault - motor or ESC - more likely ESC - or bullet connectors - or bad wiring/solder connection. If your'e brave enough, and don't have access to a new ESC, identify the flip direction, swap opposite ESC's and see if it then flips in the opposite direction. If it does - you can rule out any issues with the Naza controller or RC transmitter/Receiver issues.

If you watch my posted vid - my broken ESC was the one attached to the blue led lit arm on the extreme left hand side of the screen (pointing directly at the garage door) when the video starts. Watch closely the direction it flips. When you've identified the direction of the flip you can concentrate all your efforts on that motor (good tip - mark the suspect one with a felt pen or tape after you've identified which one - so you don't forget or get confused during re-tests)

Hope that helps - post a video of the flip if you have one - if you can't figure out the direction of the flip, more eyes see it to analyse the better. Geoff from Quadcopters helped me out on this one when it happened to me after many tense hours of presuming dark forces just didn't want me to fly my Quad!! - it knocks your confidence in trusting your Quad too - so don't give up whatever - lets try & sort it!

 

[Dale UK]

You may have just solved a similar problem I'm having.

How did you verify that the ESC was shorting, or did you just assume because the problem want away after removing the cable tie?


Jack

Hi jack - the problem doesn't neccassarily go away when you remove the cable tie because the damage (bending of the inner heat-sink plate) has already been done - although it may allow it to spring back a little - replacing it if you have identified it as your problem is the safest way. (the formula is: 'replace x1 relatively cheap ESC = potentially saving entire expensive Quadcopter')

Dale

 

[Dale UK]

Oh - and if you've invested in any posh props like Graupners or alike - during the experiments, swap back to your old DJI originally supplied cheapo props - they're much more flexible and less likely to be damaged. (do consider replacing them with the Graupners when you've fixed the problem though - much better, smoother flights!)

 

[jforkner]

Hi jack - the problem doesn't neccassarily go away when you remove the cable tie because the damage (bending of the inner heat-sink plate) has already been done - although it may allow it to spring back a little - replacing it if you have identified it as your problem is the safest way. (the formula is: 'replace x1 relatively cheap ESC = potentially saving entire expensive Quadcopter')

Dale

Again, how did you verify that the ESC was shorting?

 

[Dale UK]

Jack - read above posts ...... identify failing motor - check solder joints (unlikely if you took care) - check bullet connectors (possible) - very unlikely to be motor itself - (and unlikely to be Naza) = ESC

I don't know of an 'actual' test you can perform on an optical ESC except the one I mentioned in my earlier post (the swapping game) - unless someone else knows of one - but problem there, is it's different 'live' and flying on your Quad anyway.

 

[plasticjoe]

OK I pulled the top plate off the Hexa and tied all the wires down neatly. Also a couple of the ESC's were strapped pretty tightly down and the ties were over the plates under the heat shrink over the ESC. So I ran my finger under each plate on both sides of the plate through the heatshrink and pulled them up a little. None were blaringly bent.. but I see how if it twists in flight or when swapping out a battery from the frame flexing something might short out. I'll toss some old props on it and see what happens. I tried to get it to act up without the props last night and naturally it woiuld not. I emailed DJI and they said that there might be something wrong with the Naza... and to contact my "dealer"
Unfortunately I got this used ( less than 20 flights ) from a guy on a site with "Groups" in the name. I have a friend who is a team pilot for an online heli hobby shop checking if I can send it to them. Should know in a day or two.

 

[jforkner]

Jack - read above posts ...... identify failing motor - check solder joints (unlikely if you took care) - check bullet connectors (possible) - very unlikely to be motor itself - (and unlikely to be Naza) = ESC

Dale,

I have read all the posts including #24 where you stated, "Because of the overtightened cable tie it had caused the plate to short on one of the board components - but only occasionally and randomly!!"

As I nay have a similar problem, I'm just curious how you determined the bent ESC caused a short (especially if it was random)? Sounds like you determined the ESC was the problem and just assumed there was a short???


Jack

 

[Dale UK]

Jack ... I see what you are getting at now - why the conclusion of a 'Short' specifically? - well when I removed the heatshrink cover of the ESC it revealed the heatsink plate which had a bend in it and a couple of kinks on the edge of the plate in line with the bend. Between the plate and the circuit board is a thin layer of adhesive rubber, protecting the plate from shorting against the board (top side - large component side). This rubber layer had been punctured badly in one place - opposite the tallest component on the board - and had several partial punctures around the middle area where the cable-tie had been tightened. There was a chance that replacing the rubber insulation may have solved the problem - but in case this shorting problem had then resulted in damage to any of the electronics, based on the formula I wrote earlier in #31, I decided to change the ESC

Flown lots since replacing ESC - no problems! (oh, except a DJI motor falling to bits in flight)

Hope that helps

 

[plasticjoe]

Flew it yesterday at lunchtime 3 times... no flips. Good run of luck or problem solved ? Plan on flying another 3-4 flights today at lunch. We shall see.

 

[jforkner]

Thanks, Dale.

Jack

 

[plasticjoe]

OK... 4 flights in at lunch today.... so far... 7 flights total... no flips... Speed controls the issue maybe ? I am real careful now when I pick it up... not to grab the arm and the speed control also. We shall see... 4 more flights tomorrow weather permitting.