JR290 installed and have some problems now

[03silver]

Had a perfect tail from day 1 here, until I replaced the stock align tail servo with a jr 290.
Inconsistent violet tail wag now , flies great, sometimes can get a few packs in without it happening, and then for no reason big bad violent wags happen, can barley land it.

Had to hit throttle hold up high the other day because I could not get it back to me after it started freaking out. Only busted a skid which is cool and why I love my 250. It also feels like the gyro gain is a tad too high, but lowering the value does nothing.

Any ideas?
I’ve played with belt tension, rebuilt the tail, tried a new belt, blab la bla the
Heli runs really smooth with no vibrations, but something is triggering this nonsense.
Do you guys think it could be JR290 tail servo,

Thanks

[Ozz58]

It was happening to mine with the 290, but only after doing flips or light 3-D. Almost crashed it the first time it happened it was so bad, but taking it out of IU the wag stop intime for a great save. Was fine in normal pattern flying. I turned the gain in the gyro down until I could flip it without it wagging.

[dbennettya]

See here to see if it may help your problem:

https://www.helifreak.com/showpost.p...86&postcount=4

Good Luck, Don

[03silver]

OZZY - good advise about switching off IU, But my regular mode is 100 throttle from the go, what do you use in normal mode? Flipping seems to aggravate my tail problem too!

DON - I just backed down the gain to 23 and got drift, seems to hold at 25 for indoor hover
My radio is a DX8 i used a setting of 29 for the gyro with kdbb tail blades for super fast flight.
I will try to test it outdoors if the weather cheers up here,

Thanks for your help

[eightythree]

Tail grip bearings! Always check them even if you think they are good. just a thought

Static seems to be an issue with these little belt drives as the weather gets cold and dry.
My used 250 had major static glitches that made the tail wacky and even rx resets..
I grounded the entire system. RX negative, to motor mount bolt, to boom.

I run a low curve in normal mode. I always setup 3 complete different curves for a little guy like this.
Ive seen guys freak out and hit TH because of uncontrolled wag when u can just flip to normal mode.

[03silver]

Originally Posted by eightythree

Tail grip bearings! Always check them even if you think they are good. just a thought

Static seems to be an issue with these little belt drives as the weather gets cold and dry.
My used 250 had major static glitches that made the tail wacky and even rx resets..
I grounded the entire system. RX negative, to motor mount bolt, to boom.

I run a low curve in normal mode. I always setup 3 complete different curves for a little guy like this.
Ive seen guys freak out and hit TH because of uncontrolled wag when u can just flip to normal mode.

I never saw the use for normal mode, but this is a great suggestion.
I will set up some low curves for my backup plan.
As for the tail bearings, I've never checked them.
Thev'e seen 200+ flights now, should I blast them with some WD40?
I don't want to start grounding the electronics

[eightythree]

Highly doubt that will help. Ive even had bad align grip bearings out of the box on my 450pro v2. I just picked up bearings fom my lhs for $4. Make sure to put locktite the hub, not the grip screw.

[eightythree]

I would also like to mention that not all setups will work the same.. "your mileage may very" sort of deal.

Switch to the 37mm tail blades. The KBDD may just be to big and rigid.
Make sure the tail system is bind free.. oil the tailshaft and pushrod holder.
Silicon oil the belt.

[03silver]

Thanks 83, I will try it today with the 37mm tail blades and let you know if it helps.
I have not used those tail blades since installing the JR290 gyro servo, it might do the trick.

[QueadlunnRau]

I also had the violent tail wags with my Ds290g + Spartan Quark. Tried everything, from every tail blade, to adding chinese weights. The only thing that would work was to set my gain on my DX7 to 59 which was mushy.

I've since cured this by getting a MKS Ds95i @ $95 it's a pricey bastard, but now my gain is at 65 and my tail is ROCK SOLID with never a wag of death anymore.

I'm not sure what was up with my 290g wag of death issues, I'm leaning towards not enough torque to maintain some manuevers.


Here are some other threads about it.

https://www.helifreak.com/showthread...t=death&page=2

https://www.helifreak.com/showthread...ighlight=death

[03silver]

QueadlunnRau - There are acouple JR 3500g servos in stock at the LHS but no MKS stuff. Do you think this one will work like the MKS Ds95i @ $95

JRPS3500G
Servo - Ultra Speed Mini T/R
$79.99 Save $20.00 (20%)

• Ultra-Speed Servo for Instant Tail Control Reaction
• Ultra Precision Nylon Gears
• Perfect for 450- to 500-size Helis
• JR's legendary digital holding power and resolution
• Use with 4.8v only

It wasn't easy to improve on the 3400G servo with a 770 3D gyro for 450- and 500-size mini electric helis, but JR engineers have done it. The new DS3500G boasts .06 transit time along with big-servo precision. Provides "big helicopter feel" for ultra-precise hovering and locked-in yaw control for aggressive 3D performance.

[Ah Clem]

I started out with a JR290 on mine and it did not work out.

Upgrading to the 3500G, along with hand fitting the tail pitch change mechanism, installing the third version of the tail blade grips, the metal tail rotor pitch control arm, installing metal pulleys, and upgrading to KBDD Tail Blades finally corrected the problems I was having with mine.

[03silver]

So I flew 2 packs today and had to reduce gyro dain to 22 on the DX8 to move fast into the wind with no wag but everything else felt wrong.

tail was not stopping nice very mushy like QueadlunnRau's

Tomorrow I will try the 37mm blades, and then inspect the tail bearings.

Will the JR 3500 die out like my original Align DS420 did? Is it better in that way?

[Ah Clem]

"Will the JR 3500 die out like my original Align DS420 did? Is it better in that way?"

The JR3500 is a very high quality servo. Quicker and more powerful than what you had been using, and it has a three year warranty (at least the last one I bought did).

Make sure you run it on 4.8 to 5.2 volts.

[03silver]

Problem solved!!

The tiny ball link on the tail servo arm was moving, the hole was too big and there was slop at the link.

Drilled out a new hole with a smaller bit and the ball is tight in the arm, and no more death wags.

Also had to go back to the 37mm blades with this servo to do good speed runs,
Flew 8 packs with a solid tail yesterday!

Thanks for all the help! Great forum here!!