UM servo/board alternatives?

[prof_fate]

I like the UM planes and have a Champ that has had servo issues. From reading here and talking to the local hobby shops it seems the quality/durability of these boards/servos is not the best.

I'd like to get a UM corsair and a mosquito but I"m not confident of the boards/servos in them as they're essentially the same as the champ I have.

I've read that folks repower these with brushless and more cells but haven't come across anyone upgrading the boards/servos.

are there servos this size out there?

*my issue was a jamming rudder servo after about 2.5 to 3 hours of flight time. And it got progressively worse to the point now the servo jams every minute -sometimes it frees itself and sometimes not without a helping hand - bump the gears and it runs fine for another minute. Doesn't jam in the same place each time and since throttle/elevator work it's not a receiver issue.

HZ sent a new fuse and if the weather settles down when I'm not at work (stars much align just soooo LOL) I'll give it a try. I"m just not confident that this one will last any longer and would consider an upgrade if one exists.

[JetPlaneFlyer]

Super light ultra micro RC gear is never going to have the durability of standard gear, this is just a fact that needs to be accepted if you want to fly ultra micro models. Having said that the Spektrum micro bricks are generally not too bad, though the odd jammed servo isn't unknown.

Hobbyking do some cheap micro gear with normal type rotary servos but how reliable that stuff will be is very much open to question, and although it's very light, it isn't as light as the Spektrum brick in the Champ.

http://www.hobbyking.com/hobbyking/s...c_0_075kg.html
http://www.hobbyking.com/hobbyking/s...dProduct=18827

But then you would need a separate ESC (ref brushless conversion thread)


Steve

[CNY_Dave]

Originally Posted by prof_fate

*my issue was a jamming rudder servo after about 2.5 to 3 hours of flight time. And it got progressively worse to the point now the servo jams every minute -sometimes it frees itself and sometimes not without a helping hand - bump the gears and it runs fine for another minute. Doesn't jam in the same place each time and since throttle/elevator work it's not a receiver issue.

I have seen this happen- the gear, probably the large one, has a very small deformation of one of the teeth. It can happen from an impact.

With a magnifier and a sharp blade/point I was able to reshape the tooth that was damaged.

These critters are pretty tough- I have had a champ and a UM T28 for a bit over a year and I still beat the heck out of 'em.


Dave

[prof_fate]

The HH guy did ask about impacts but the board is mounted internally on silicone, i've never crashed it -at least not what I'd call a crash -a nose over on landing perhaps.

I'll check out the gear more closely, but if this were an issue, as in a common one, you'd think the forums would be full of noise and chatter about it, especially on the planes with the exposed aileron servos that would get a whack on every grass landing.

[CNY_Dave]

It's not that common, just know a guy that was even better than I at finding interesting ways to break stuff.

A sure sign is if you turn the lg gear by hand and it feels 'notchy' at one or more spots, where you feel it over and over as you turn the gear.

Dave

[philipa_240sx]

I'm with CNY_Dave, check gears. Even a bit of debris, silicone, etc can cause all sorts of weird behaviour. Also check the linkages to make sure nothing is binding.

Another possibility is dirt on the feedback potentiometer. I had this issue with my PZ Vapor and the servo would stop or work erratically. To clean it, you need to remove the servo (held with screws on the backside) and clean the carbon feedback trace on the circuit board. It's fiddly work for sure and you have to remove the brick from the plane to do it.

I've found Horizon Hobby support to be very good. They've sent me replacement parts under warranty with no hassles. Why not give them a call?

Finally, you can buy just the replacement servo mechanics:

EFLH1066 - Replacement Servo Mechanics: Short Throw

Don't worry that's it's an E-Flite part, it's the same servo used in nearly all the UM planes and Heli's.