New Tarot 680 - lost confidence

[Grimbo]

Ok, so finally got the build finished.  Similar power/motor set up to Orfordness, but I am thinking I am going to regret this.  The Afro slim esc are in the arms which made it a bit of a pig to build and imposible to get at once in situ.

So far I';ve had 6 or so shortish "set up" flights. The arms where the esc';s are do get slightly warm to the touch but nothing untoward I think.  Most recent flight I was testing rtl and failsafes from about 5ft height and on the last rtl it performed as expected until it reached altitude (30ft) prior to descent at which point no 3 motor cut.  It compensated as well as it could (I wasn';t quick enough to get control back) but came down hard (but relatively level) but luckily little damage.

Got it back home on the bench but of course with the esc in the arm I cannot see the esc leds.  Tried to run it and no 3 would not run.  Checked as best I could that it is getting power and recalibrated no 3.  lo and behold, it now works.

But, I have lost confidence in it as I do not know the underlying problem.  Anyone any ideas?  I do not understand why it would just shut down and why recalibrating would fix it (unless that is just a coincidence). It was a good 15-20 mins between the landing and getting home and putting it on the bench so if hot it should have cooled.  Can they just "lose" calibration?

Bit of a bummer really as I was supposed to be taking it to a big family gathering at a country house in Norfolk at the weekend to shoot some aerial video, but now loss of confidence and the possibility of danger to life etc (as well as embarassment) I';m having second thoughts.

[Prometheus]

Hi,

I have a 680, it';s awesome. Don';t loose confidence, just keep posting on here. I had lots of start up issues.. and lost of help from here...   


It';s probably a heat issue, I have my ESC';s under the motors to keep them cool, some pop them in the ';sandwich'; part of the frame.  By the time you get them to the bench they will be cooler. I would suggest making some extension leads and moving the ESC';s out into free air where they can cool down. If nothing else, it will help to eliminate a heat issue.

I have 30A ones, what do you have ?

P>

[Hands0n]

Hi @Grimbo - as @prometheus says, don';t give up. Whatever it is will be solvable, its just a matter of tracking things down.

My first thoughts are to the ESC.  As they are Afro, and SimonK, there is no actual need to calibrate the ESC and doing so may very well put them out of basic adjustment.  By default the ESC';s parameters are factory set. Calibration will overwrite these and may introduce discrepancies. 

My own experience with Afro supports this in some respect - I had an ESC that would not re-arm after a few flights. It seemed to be a thermal thing, as after letting 15 to 20 minutes pass it would arm okay.  When failing it would flash a red LED indicating a "Phase B" failure (whatever that is!). 

On another forum, and from Timecop himself, the advice was not to calibrate Afro ESC.  So I re-flashed them using the USB flashing tool and RapidFlash software for Chrome browser.  That is the only way to get the factory parameters back. 

Doing that has resulted in no more ESC issues, I have flown dozens of back to back flights and the ESC has re-armed each and every time without fail.

Now that isn';t the same as an ESC halting a motor in flight - I have never had that - but it may be a good place to start, eliminating that particular aspect that may be complicit.

[Grimbo]

Thanks for the answers guys.

Well, I did take it with me and after less than 5 minutes in the air no.3 failed and we had another hard landing.  Damage limited to both undercarriage skids (always have thought they were flimsy), and a snapped gps mast.

The esc';s are Afro slim 20 amp (de-rated 30 amp). I didn';t know that you should not calibrate afro esc';s (I have them on another hex and calibrated those and they have been fine).

Anyhow, I cannot go on like this, so it is back on the bench for a tear down and re-build.  I have to partially dismantle it anyway to get to the problematic esc/motor so I might as well go the whole hog.  I shall have to look into this reflashing lark.  Can anyone point me to instructions on this?

thx

thanks

[Hands0n]

Here';s a reasonable YouTube shortie on how to use the USB Linker tool to update/reflash the software on the Afro ESC.  The tool can be had from HK or you can probably pick one up for a few quid more in the UK also.  There is a Turnigy tool and an Afro branded tool, they do the same thing.

Make sure you disconnect the power wire from the ESC to the Linker before plugging it all up - that';ll save you the magic smoke thing (thats not good). 

Use RapidFlash utility - that is a Chrome browser extension. There are drop-down menus in the app for the type of flasher tool you';re using and the various versions of SimonK that are available. The label on the ESC usually has the specific .hex file that you';ll need.

HTH

http://youtu.be/F9kWjTiH6xc

[flybywire]

Grimbo, do you not have a spare to swap out?  I know one or two on here have enclosed the Afro slims, but I had some issues with ESC';s overheating, so personally wouldn';t lock them away again without airflow myself.  As you';ve discovered, it';s a sod to get at if the devil drives.

Andy

[Ynot6]

ESCs belong on the OUTSIDE of arms, they need all the cooling they can get. i';m about to start building a small (1M) wing, the instructions include cutting out an "electronics bay", the ESC will stay on the outside.

[Grimbo]

Thanks for the replies guys, and for the helpful hints.

Teardown and rebuild underway, it';s going to be a bit like starting all over again!  Oh well, at least it';s not flying weather.

[flybywire]

Yeah, i think we';ve all been there grimbo, at one time or another, but you';ll find it';s a satisfying feeling when you nail it, and your confidence is restored.
With todays equipment, these things are remarkably reliable, once you';ve ironed out the bugs.

Keep going.

Andy

[Grimbo]

Well, frustration and despair ratcheting up now, with more questions than answers.

Tarot rebuilt with  ESCs reflashed and mounted in fresh air.  Did a short bench test on each ESC/motor combo but before taking flight but thought I would do a little ground test first, just arm it and run it up, give it a little hop but not enough to really get airborne.  Cogging on 3 & 5 rapidly followed by fried ESC on No 3 with no. 5 very hot.  Pic attached.  All this within 20sec.  My ground test was just like this:
Smartdrones SD-M550G 4408 Brushless Motors - Sync problem with 4s LiPo (SimonK ESC)
with the same result.  Interesting smell, too.

Now, this prop/motor/esc/battery set up is identical to that of Orfordness;  RCTimer Hp 4108 720Kv, 12x3.5, Afro slim, 4s 5000maH,   which came from Peter King, so what gives?  Though I do see that PK latest build list on the website has changed away from the Afro slim esc.

I have done a bit of research and see that there is a distinct possibility it';s the SimonK firmware problem with high pole count motors and/or 4S Lipo coupled with the Afro Slim not being up to the job or having quality control issues (3 out of nine of mine have now overheated with 1 burnt out).  (And why always no.3?)

I know it';s not the Tarot';s fault, but I am becoming a bit sick of teardown and rebuild (and throwing money at it) (and it cannot do the frame much good to keep doing it).  This is the last time.  I';ve ordered some Hobbywing 30A platinum which seem to get good reports and will go on straight out the box.  It is going to be do or die.  There is no reliable info out there as to what combo will or will not work, what is golden for one person is absolute rubbish for someone else (which may also have something to do with the quality of parts, most of which come from far east).

If it doesn';t work this time I';m going back to my trusty 450 quad and micro spider hex, which fly great.

Ok, semi rant over.  I';ll get in touch with my inner zen and calmly start to remove the 22 or so socket heads to pull it apart...........

[miniconverter]

Where are the ESCs mounted, in the middle or under the motors?

[orfordness]

Just a thought but your picture is not a 680 pro (which is a hex), but a 650 quad?

most of the advice given seems to be around a hex, for a quad i think those motors and props are overkill?

unless you have linked to the wrong video?

Steve

[Grimbo]

Miniconverter - The esc';s are (were) tie wrapped to the outer end of the arms, just inboard of the motor mount, so in good airflow.  Originally they were inside the arm but I moved them after the first failure

Orford_ - The video is not me nor my quad.  It is an example I found on youtube of exactly the same problem, demonstrating the loss of sync issue with SimonK firmware.  Given power is identical to yours that you obtained from PK, and yours seems fine, I am at a loss as to why I keep getting this.  The high pole count/4S Lipo/SimonK firmware issues seem to be frequently brought up in various forums as the potential culprit for motor cogging leading to failure.  I';m not saying that is the case for me but its a mighty close coincidence.  Be interested to know how yours is holding up.

Hex is now disassembled and stripped of esc and motors, solder pads all cleaned up, so just waiting for new esc to arrive before commencing what will be the final attempt.   I worked out that I have spent  something like 48 hrs of build, stripdown, rebuild, stripdown etc time for  no more than 4 minutes total airtime.   I think all this electric malarky is just witchcraft, my i.c. helis were never this bothersome.

[Ground Engineer]

Did you check your battery level.  Sometimes if the cells are near 3.3v one of the motors cuts out.

[miniconverter]

The reason I asked about where the ESCs are is due to the length of wire from the battery to them, you could try extra caps on the wires.

I have been reading up on it and half the RC world seems to think they are essential the other half think it makes no difference. I will be using them on my 680 when I get round to building it and may be worth a try for you.