(resolved) What could cause this?? Another bad SK540?

[Slyster]

I replaced the defective SK540 on my Outrage 550. The new one set up fine and initializes to green as it should... but is unflyable. I don't use gov mode.. it is powered by the Jives 5.6v BEC with the low voltage warning off. Bound as DSMX 11ms.

Went to fly it today for the first time.

When I spool it up.. everything is smooth for the first few seconds after reaching full headspeed, then suddenly the tail will go nuts and jerk back or forth a couple times and the SK540 LED will turn red and the heli spools down... I tested 6 times and every time it did the same thing. I tried rebinding twice as well. Sat lights solid upon shutdown. One time the SK540 reset when the motor shut off.

... one time TH wouldn't even work at the heli continued to stay at full headspeed for 10 seconds... scarey seeing that.

I tried one satellite at a time.. same thing.. so that rules them out.

There are no vibrations.. it was flying beautifully with the previous vbar and there have been no changes other than the SK540.

Another bad SK540?

(I flew the Goblin after that so the radio is fine)

[Arcturus97]

Yikes that is scary, especially how it wasn't passing on the right throttle signal. Sorry to hear it. No ideas here. 2 bad units in a row, buy a lotto ticket or something.

[Slyster]

I guess one thing I should do is move the proven KS540 from the Fusion to the 550 and see what happens. That would be the quickest thing to try.. because yeah.. to get two in a row would be exceedingly rare.

The only thing I can think of (although I don't know if it would make the LED turn red 10-20 seconds after spool up) is I removed the toridal coils from my Jive 80LV. But I've never used those coils on any other of many helis that have had Jives on them.

Does anyone have any ideas? (other than pulling the SK540 from my Fusion). I am in contact with Alvin as well. He ruled out vibrations as a cause at this point.

[Larry227]

Sorry about your bad luck. At least you know the heli itself is fine because all you did was swap out FBL units on a working heli.

Since everything is already setup on both units I would save both files, do the swap and import your setup and give it a try. That would tell you right away. Oh and stand way back.
Unless of course the units are buried inside the frames and it would be a major pain to disconnect/reconnect the wiring.

[Slyster]

Yes it would be easy to swap.

Odd thing first... I cannot reproduce this indoors! Tried and tried with the mains off and tail link off.

It is a belted tail heli and now static comes to mind...? It was cold and dry out there.. and nice and humid in here.

First step - I think it to turn logging on (Alvin's request) and lube the belt really good with silicone spray and try again tomorrow after work.

Second step - swap SK540s

[Larry227]

Yeah could very well be static. Lube the belt and it wouldn't hurt to ground the boom if it's a plastic tail case.
Let us know how you make out.

[Slyster]

Larry yes it has a plastic tail case.. but this particular O550 has G10 frames.... and G10 doesn't conduct electricity... what should I ground the boom to?

[Larry227]

A motor mount screw.

[Slyster]

Ah! Thanks. I'll be doing this shortly. I managed one failure on the bench now.. but since lubing the belt I haven't been able to get another. More flight tests tomorrow. I sure hope that's all it is.

[Larry227]

Sly if you look real close at this picture you can see how my boom is gorunded on my 6HV. It's the white wire screwed to the bottom of the boom right behind the case. The wire then runs into the frame and back out behind the motor and goes to a motor mount screw.

[Slyster]

Did the ground mod. I can't spool up now to see if it helps since everyone is asleep

Alvin is leaning more towards power brownout... I did manage to get a few failures on the bench (after applying silicone to belt) and log it. I sent the log to Alvin.. so hopefully that might shed some light.

This would surprise me though since the Jive BEC's are famously good at 15A peaks... and they are working flawlessly in my Fusion 50 and Goblin 700... and this same 550 for 2 years now.

[backburner1955]

Clean up your wiring and keep servo wires away from motor leads.

[Slyster]

Motor leads.. you mean the three going to the motor from the ESC? They are clear and free by many inches to any other wires.

I did bundle the ESC master and slave wires with the servo wires.. would that matter?

This is basically the exact setup as when I have the vbar.. nothing has changed besides a replacement motor which is running fine.

[backburner1955]

Master and slave wires are ok, also, I don't like twisted servo wires. I have seen too many instances, not in heli situations, where wires twisted "cross talk" unless it is designed to eliminate it as in communication cables or instrumentation cables. But in that case, there are multiple pairs twisted at different rates to eliminate cross talk.

I just think it may cause glitches in sensitive signal applications like a FBL controller. BUT I am sure DomD will come in and prove me wrong.

[tacomaster]

Originally Posted by Slyster

Motor leads.. you mean the three going to the motor from the ESC? They are clear and free by many inches to any other wires.

I did bundle the ESC master and slave wires with the servo wires.. would that matter?

This is basically the exact setup as when I have the vbar.. nothing has changed besides a replacement motor which is running fine.

I bet it was static. Id get a ground 9n there asap.

[Slyster]

Done. Testing again tonight.

[backburner1955]

Good LORD!!!!!, is that wire protecting from Lightning or just belt static?... All you need is a wire the size of servo wire.

[Slyster]

It was temperary just for a test... and it worked! NO ISSUES today. It was static I guess. It never bothered the Mini-V but perhaps the SK540 is more sensitive? Now I will figure out a better long term solution.

6 great flights until my belt broke. But I got down with just 1 broken link and broken skids.

I LOVE the SK540 on my O550 too! Really felt good. Again better, for me, than Vbar.

Now I wonder if the screw (to ground the boom) hit the belt. How to ground the boom without hitting the belt? I might use the servo mount and do a little sanding to make a contact.

[neoalchemist74]

I've had similar occurrence B-4 and in my case it turned out to be a servo that was drawing crazy amps and causing my RX to brown out. The servo eventually smoked which is how I figured it out. Wish I would've had one of these. http://www.horizonhobby.com/products...t-meter-HAN172
It would've made life much easier.

[Larry227]

Originally Posted by backburner1955

Good LORD!!!!!, is that wire protecting from Lightning or just belt static?... All you need is a wire the size of servo wire.

Sly is that a boom mounted tail servo? Looks like it to me. You could just scrape some paint off the boom under one of the clamps and clamp your grounding wire between the clamp and the boom.