Blade 400 dicky servo

[SeaComms]

Hi all.

Anyone seen this before?

I just drove all the way down to the local park to try my first real flight (after a few back yard hovers) and on just starting to lift off the ground it lurched over forward and dumped the blades into the ground. Stuffed the tips on the blades and bent the feathering shaft.

Got home and replaced both, then did a quick check before next attempt to hover and noticed the swash was not level. Back to the table, disconnect the motor and this was what I found.

You tube Video of weird servo (http://www.youtube.com/watch?v=cY7CrW6R7D0)

As soon as any load was put on the servo (as in some pitch coming in) it jumped about 1/4 turn up pushing the back left of the swash up causing forward elevator and right aileron. Net result tilting it forward and into the grass. Note, the servo is not skipping teeth or anything, it is actually driving suddenly an extra 1/4 turn as tho the pot that senses the position is spinning.

NOT HAPPY JAN........

[GreenBar0n]

That is strange, have you removed the servo and inspected it out of the frame?

[SeaComms]

Good point! Was too peed off to pull it out, will go and have a play with it now. Have sent the video link to the supplier and will see what they say, as its only 2 weeks old.

EDIT: Just pulled it out of the heli to have a closer look, looks like must be something loose inside. If you hold gentle pressure on the top (where the screw holds the arm on) it travels twice as fast as it should and 4 times the distance. But if you let go, it operates normally around where it last zoomed off to!

[sokal]

i know doing what you can when you start before you upgrade is a smart thing to do.
but the stock servos are very unreliable. my upgrades were mostly done for peace of mind. they always work always center.

with the stock motors iv had bum motors, striped gears slower movement
never centers the same. seems to act doiffrent every time i flew.

that was a bit scary so i looked for good dervos and found what most put in thier helis
abeter quality and defenetly peace of mind

[singingperry]

Could be a servo gear is completely stripped. I replaced two servos and now have the old repaired servos as spares. Replacing the servo gears are easy if you use one sevo as a guide to put the gears on the right axles in the right order. PS place a piece of scotch tape around the bottom of the servo to keep the electronics from falling out of the bottoms of the servos. .and keep extra sets of gears handy. Even when I called Horizon Hobby they said they're on back order till late April. But the lhs didn't have any problem getting plenty of fresh ones "Just got em in today!" New gear sets are just 3 bucks apiece, bought four sets until I can afford different servos.

[SeaComms]

Yep, I found the problem... Definately a dud servo. LHS is happy to replace and looks like they will also send new feathering shaft and blades as well??? Will see on that one.

The servo is really weird, no load it works fine, put a load and it doesnt skip and not move as far as it should like would be expected from stripped gears, under load it actually moves 3 to 4 times the distance it should!

I think they are very under rated for the loads incurred by the cyclic demands, so I will graciously accept the replacement parts and put the servos aside for a more docile flying beast like a glider or similar.

Just awaiting a freight quote from Central hobbies for some HS-65's (only $20 US each!!) and the JR 285 for the tail.

Cheers, Dave.

[skigolfmike]

IMHO, I think it makes more sense to put 285s on the cyclic since they fit in the existing servo slots. I'm not sure the 285 would be the best TR servo. A lot of folks like the JR DS3400G. YMMV

[terrybeb]

IMHO, I think it makes more sense to put 285s on the cyclic since they fit in the existing servo slots. I'm not sure the 285 would be the best TR servo. A lot of folks like the JR DS3400G. YMMV

I second that suggestion.....http://www.horizonhobby.com/Products/Default.aspx?ProdID=JRPF310H
This is the latest kit for 450 size heli's to come out.
But this is the one that is used right now...http://www.horizonhobby.com/Products/Default.aspx?ProdID=JRPF300H

[gatherman]

I had this problem on a replacement servo not to long ago. I have since replaced them all with HS-65HB's.

[widower]

I found one stock servo with a bad solder joint inside. Re-soldering fixed it.

It's possible that the extra load you are applying is causing greater current draw and with a bad solder joint, causes the processor in the servo to act funny.

[Wolfpackin]

Just a thought but since many people are having problems with ESC overloads, overheating and shutdowns it might make more sense to use the analog HS65's on cylic instead of using four digitals, that draw more amperage, and run the risk of having ESC problems.

I know someone will jump on me and say they are running the digitals and have no problems.
But I can tell you this; It seems that a large majority of the people having ESC issues are running four digital servos and one with high torque on the tail.

Feel free to flame away and correct my thinking.

[SeaComms]

I have already thrown in a little Hobbywing 3amp continuos 5amp peak UBEC, cost me like $15 but I figured if it saved a crash from a glitch it was worth it. It weighs buggerall and I have it strapped to the side just below the battery.

That said, I am upgrading to HS65's for the cyclic anyway since one of my servos decided to go wacky.

[skigolfmike]

I have no problem with ESC overheating since I added an external BEC.:tongue

[SeaComms]

Oh yeah, I forgot to add - after about 11 minutes of hovering in the backyard the ESC was just nicely warm.