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e-Minicopter Joker > Need some trouble shooting help
 
 
BungeeMike
Senior Heliman
Location: Honolulu, Hawaii

Aloha Group
I need your expert opinions as I am pulling my hair out.
Setup
Maxi joker v2, Big blue, and poptart esc, Jr 72 pcm radio, gy 401, 12th pinion turning 1350's rpm gov mode, JR 9303.

Previous problem (not sure if related) on the second flight of the day afer 15 min cool down the heli shortly after take off would turn left like you are giving it rudder input. We were able to get it back, it always does it on the second flight, nothing else affected. Changed out 601 gyro to 401 problem eliminated.

Current problem
Usual spool up and afer about 3 minutes into the flight it lost power, pilot lowered throtle up and down a few times then it caught and was able to land, all flight controls fine. I checked all connections, swapped batts and tried again. We kept it high this time just in case, it acted fine we were into the flight about 6 minutes and it did it again, like it was un plugged. Glad we had the extra hgight or I would have been swimming as were were over the ocean.

Nothing hot, barely warm to the touch on motor and esc.

History, unit was purchased used with aprox 10 flights on it, it was professionally built and after checking and inspection this was verified.

I am going to swap out RX and TX with different one and take that out of the equation.
Any hints appreciated.

Mahalo
Bungee
04-25-2008 02:33 AM
 
 
phil007
Senior Heliman
Location: Austin, Texas

I would first be checking the poptart esc. Do you have another esc to try? Can you safely duplicate this cut out on the ground with the blades off?

Edit: If you can duplicate the motor cutting out on the ground with no blades, connect a servo in parallel with the esc. When the motor cuts out the servo will tell you if it's the esc or rx causing the power loss.

Phil
04-25-2008 04:17 AM
HOMEPAGE  
 
 
BungeeMike
Senior Heliman
Location: Honolulu, Hawaii

Phil
Thanks for the hints, I just started to try and duplicate the problem with the blades off no luck yet. Do you know if this esc needs the ferrite ring on it or not. It doesnt have one, my other smaller esc all do, looking for the esc manual now. I dont have another esc that will handle this motor
Mahalo
Mike
04-25-2008 04:41 AM
 
 
phil007
Senior Heliman
Location: Austin, Texas

I don't know about the the ferrite rings. Maybe someon else will chime in that can help. That's not a fun issue to be having but at least it sounds like you've got a good pilot.

Phil
04-25-2008 04:54 AM
HOMEPAGE  
 
 
BungeeMike
Senior Heliman
Location: Honolulu, Hawaii

Yes my pilot is good and we got lucky, 5 ft off the water before it kicked back in, stressful day. I'm hoping its something simple I dread the thought of buying another one of those ESC or sending it back to Germany. While running it I tried wiggling the wires, shaking it, nothing, purrs like a kitten.
Bungee
04-25-2008 05:05 AM
 
 
rroback
Key Veteran
Location: Irvine (UCI), Ca

I'd check all bearings, belts, make sure it isn't failsafe kicking in. Also check wires, for any mysterious chaffing.

Rhett... There's no power like E Power!
04-25-2008 05:24 AM
 
 
ehx
Senior Heliman
Location: Northern Minnesota

As others have said I'd look at the ESC first, but it could be a bad connection anywhere between and including the motor and the batteries. Cracked wire, cold solder joint, etc.

As for the receiver, I assume you had control of the servos, just no headspeed. That makes a receiver problem very unlikely.
04-25-2008 07:54 AM
 
 
Highviz
Senior Heliman
Location: Newbury, Berks, UK

Hi Mike - how new are the lipos? (Age and cycles)

I had a similar problem that cost me a repeat visit to do a job when I had both packs fail on the same day. They showed full voltage before takeoff, but would not deliver any current / capacity, so heli would spool up and takeoff but run out of go within a minute or so of flight. One pack only had 30 cycles and the other 50 and neither showed any puffing or damage, so I couldn't believe they had both gone bad at the same time. Without the blades it would run quite happily. - Took me a while to realise it really was the batteries

Malcolm
04-25-2008 08:09 AM
HOMEPAGE  
 
 
nooobs
Veteran
Location: Toronto, Canada

Mike

My last MJ2 crash was due to dying receiver lipo batteries. Had the same symtoms. Just flying around and I would lose control momentarily and get it back. I was trying to figure it out at the time. I landed, checked it and still kept flying. BAD MOVE. Hovered some more and then totally lost control. Luckily I was only about a foot or two off the ground.

Checked out the batteries afterwards and they were definitely messed up. They were no longer charging equally and were not able to hold charge for a long time. These were my first batteries and didn't take care of them in the beginning. I've learned my lesson.

This may or may not be the same problem you're having but it's worth looking into.
04-25-2008 11:25 AM
HOMEPAGE  
 
 
BungeeMike
Senior Heliman
Location: Honolulu, Hawaii

Found the problem!!! Yea. It was the lipos or rather 1 of them on ea set. I was running 2 ea TP 5s4p 8000 mah that I just got from them. Both sets new under 10 flights on them. Didnt suspect the batts pretty much determined it was the esc and was getting ready to pull it and send it in. On our most recent shoot I put in a set of the TPs usual preflights yada yada and it started to spool then cut out. Reset everthing spooled up got about 6" in the air cut out, then it wouldnt spool at all. Thought I had popped and esc. Put in another set the True RC and everything was fine, did a little check flight over the lawn before heading off the cliff. Upon checking the packs each read 21v connected together it read 3v, What the heck. Checked again this time one read 21v and the other 0v, checked connections, solder joints all ok couldnt figure it out in disgust I grabbed the pack with meter still on it an all of a sudden I had 21v. I was holding it by the end cell and apparantly the little bit of flex in the pack made the connection INSIDE the pack to read 21v. Not sure how these things are built but Iam NOT a happy camper that a new set factory direct of TP packs nearly cost me a $8k bird. I could duplicate the voltage drop on the bench by just a slight flex on the packs, no rough handling just the usual. I'm sure TP will make it right and happy to know the cause but I'm 2 sets down going into a busy week. If anyone else has experienced this please post or ways to prevent it.
Aloha
Bungee
05-19-2008 07:24 AM
 
 
Seablade
Veteran
Location: floating around



Since your doing over water frights you might like this!
Check out this auto inflatable PFD made for dogs. Attaches easily to the landing gear on the MJ-2. The large size is the same length as the fuselage. $139.00 through West Marine store, www.westmarine.com

http://www.crittersinflatable.com/


It will not prevent your electronics from getting wet as it has to sink to be activated, but it will make recovery a lot easier...unless the wind blows it out to sea!

"Vini, Vidi, Velcro"
05-19-2008 10:52 AM
 
 
BungeeMike
Senior Heliman
Location: Honolulu, Hawaii

Seablade
Thanks, I have thought about this as well designed a last chance parachute recovery system. The life jacket would only help in a few instances where the bird would be recoverable.
My thoughts
Bungee
05-19-2008 06:23 PM
 
 
Seablade
Veteran
Location: floating around

I thought about a parachute design too, but my thinking is 180 from yours.
My thoughts were that the chute would allow you to soft land on water if you lost all control and could not auto, but once you were on the water your going under and your going to need a diver to get it back. The amount of time your under water doesn't matter because when the electrics get wet-they are wet and damaged. There is the time factor of trying to pinpoint where it landed from memory when you do get a diver after the fact.
If I didn't live onboard I couldn't afford to pay a diver to stand by when I do fly over water. I'm lucky that that there are divers among the crew and the gear, boat and diver are always ready to respond.

If you can auto it down with the inflatable at least your going to be on top of the water and it does make recovery a little bit easier as you'll be able to see it and if all else fails you could swim to it!

I'm just praying that I still have flight controls if any thing happens so I don't hit hard...water or ground it going to cause damage.
Trying to successfully deploy a chute can be done, but looking at the spinning rotors I would rather not try it. What I can see is another section of tail boom mounted with a spring loaded chute inside to eject it out past the T/R.

I would like to hear about your chute as I always look at ideas to see what is workable.
Both our ideas work for each of us

"Vini, Vidi, Velcro"
05-19-2008 09:19 PM
 
 
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e-Minicopter Joker > Need some trouble shooting help
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