almost lost my Trex500 today!

[pootman]

hello all,

I was out test flying my heli today after a couple of changes. Those chances were:

1. Turns my Spartan 760 around so the wires come out the back of the heli, and
2. Shorten the arm length on the tail rotor servo from about 11mm to 8mm so it was more in-line with the control rod guides. I also did this because I've read that it fixes low gain and tail wag issues. My gain was at 40 for this flight.

First thing I noticed on the initial test flight was that the piro rates were much faster and left was much faster than right. So I landed and adjusted my end points to try to get the right to match the left. Went back up and this time when I let go of the left rudder stick it continued to piro to the left about two full turns. So I landed to have a look but did not know what was wrong. I thought maybe it was gain and adjusted the gain alittle. Went up to try again (stupid me). Well it stayed in the left prio again but this time about 10 turns followed by a reciever shutdown. It's a 6200 and reaquired right away but as the motor spooled back up the rx shutdown again and promptly reaquired. This time I hit throttle hold and autoed from about 80ft. Aghhhh. No clue what was wrong so I put the tail rotor servo arm back to about 11mm. Went for another try but every time the motor starts to spool up the rx dies??? Could a tail servo stuck with full left burn up my CCBEC? That's the only thing I can think of that's dead. Any other ideas would awesome since I'm pretty new at this.

Pootman

[pootman]

Oh yeah, here's my setup:

Jazz55
Stock motor
CCBEC
EagleTree
Spartan 760
4 JR z3650
Align 6s 2600mAh
Spektrum 6200

I just tested it again on the bench and the receiver would die as I spooled up. I plugged my CCBEC to my computer and reloaded the firmware (although everything looked normal when I first plugged it in) and now it seems to work just fine. I also stirred the stick all over for about 30sec-1min and it's holding strong. Really weird.

pootman

[psindrup]

Have you done the (anti) static mods?

Peter

[pootman]

Yep. I've used carbon spray on the belt and ground the entire boom to the frame. I've also ground the neg on the ESC to the motor mount.

[sbmon]

There have been alot of issues with the 10amp cc bec, especially in high voltage situations. I have had one fail myself. If I were you I would start by eliminating the external bec and run the bec that is on the stock align esc.

[pootman]

well, I'm guessing that my servo arm was too short which caused it to go past 45 degrees to achieve full deflection. I knew the Spartan manual stated that I should keep the servo throw at a max of 45 degrees. Does it get stuck once you pass the 45 degree mark? It seems like that's what happened in my case when the left piro continued on its own. Now the more important question is: Can a single digital servo overamp a CCBEC to cause it to fail? Furthermore, can a BEC fail in such a way that causes it to work fine with no load from the motor then quit when that load is applied? I'm just hoping its not my Jazz55 since that was a big purchase for me.

I'm gonna put another CCBEC I have that's new and see if I get solid power to my rx.

pootman

[cbflys]

The connector on the CC BEC is its weak point. It really shouldn't be used to source more than a couple of amps (which a stalled servo can easily draw). If you are handy with a soldering iron I would recommend using heavier gauge wire and quality connector between the BEC and the receiver.

It also appears that the current draw was high enough to corrupt the flash memory. I'd also recommend contacting Castle Creations to see if that could indeed happen under those circumstances.

[merlin703]

I had the same problem.... wel not exactly the same but very similar. My rx was dying. It die and didn't know what was up. I got a new rx and everything worked just perfectly. I sent the 6200 back to the factory since it was only 3 months old. It's 'possible' that you are having the same problem.

[Madbob]

Had a CC bec die on me.Lost control for a second then it started a slow piro.Got the 500 down in one piece.Unplugged then replugged the batt and got zero voltage from bec.CC's only explanation on the warranty replacement was it failed all tests.
I just think the bec can't handle the 6s batts it's rated for since I've been running them in 3s applications without a problem for a while now.I am now trying a Hyperion bec rated for 10s and crossing my fingers.

[pootman]

Well its getting stranger! MY TAIL ROTOR SERVO REVERSED ITSELF TODAY!!!! Not kidding. After installing a new CCBEC and a couple of runups everything seem to run fine. So this morning I flew the first flight without a glitch. After such a good flight I wanted to give my Kasama tail rotor another try, so I swaped out the stock tail. Then it did it again, dies on spool up:( However, the rx regained the signal right away so I ran it up to mid stick without issues. Then I tried to hover and the heli spun around like crazy. Didn't crash nut it came close. Took a closer look and the tail rotor servo is now reversed and I had to reverse it on the tx and the Spartan. After I got home I plugged the Spartan to my computer to doublecheck the setting was indeed defferent from before and it was! I've been screwing around with RC (planes, til this heli) for about 22 years now and I've never had a servo reverse on me on its own. Maybe my 6200 is starting to freakout. BTW, I did more runups and a few test flights after re-reversing the tail rotor and all seems fine but I'll head out to buy a new 6200 or 7000 tomorrow!

pootman

[psindrup]

Well its getting stranger! MY TAIL ROTOR SERVO REVERSED ITSELF TODAY!!!! Not kidding.

That must be due to a different geometry on the Kasama tail, or that you put the arms on "backwards" (leading edge control versus trailing edge control)

Try to put the stock ones back on, and I am sure it will "reverse back"

Peter

[pootman]

Uh, yeah, I'm dumb dumb. I stared at it trying to figure out what I could have installed backwards and well, didn't figure it out. So I came to the only illogical conclusion I could think of. However, my rx random resets since my heli was stuck in a left piro incident hasn't been nailed down. I replaced the CCBEC (which I thought was the failure point) but the rx still reset itself once. It's much better than with the old CCBEC where it was resetting constantly, but the one reset left a bunch of uncertainty in the air. So I went out today and bought a new AR7000 to replace the AR6200. I'll send the original CCBEC and the AR6200 in to see if either of them are the culprit.

pootman

[rdlohr]

Are you sure your tail linkages aren't binding? Disconnect the servo and manually move the link through full range a bunch of times. You could be hanging up at one end.

Rick

[pootman]

I did check for binding early on and found no binding. I flew it 5 times with the new AR7000 today and it was flawless. So maybe it was my receiver, I'll send it in and see what spektrum has to say about it.

[rdlohr]

I did check for binding early on and found no binding. I flew it 5 times with the new AR7000 today and it was flawless. So maybe it was my receiver, I'll send it in and see what spektrum has to say about it.
OK, good luck!
Rick