HoneyBee CP2 Radio Weirdness

[scallybert]

I've been playing with my HBCP2 in a fair-sized room at work, and it hasn't gone too badly.

However, there's something kind if glitchy behaviour going on. From time to time it spasms, and rolls sharply to the right. Sometimes it's controllable, others not...

With the helicopter sitting with the rotors static, and moving the cyclic pitch stick from full left to right, at a particular point of its range, one servo (rear, l/h on swash-plate) behaves erratically. Other than at this point, the servo tracks the lever input. At this point, it jumps about 20 degrees. As the stick moves on, the servo jumps back, and continues to track as expected.

This seems the likely cause of the spasms. However, what's causing this ?

I'd guess it's not ESC interference, as the motor isn't running.

I'd guess it's not external interference, as it seems so reproducable via stick input.

I'd guess that if it was a Tx problem, it would affect more than just this servo - moving the lever left to right causes two servos to move in opposition. Only this one servo shows a problem.

That seems to sugest the problem is either the Rx or servo. My guess is it's the servo.

Is this a reasonable guess ?

[gazza]

Swap the servo connection with another one at the receiver mate.
Unplug the motor & try the movements again. If it still jumps then the servo is mashed.....

[scallybert]

Swap the servo connection with another one at the receiver mate.[...]

Yes - that's the logical way of debugging it, and what I was thinking of doing. Thanks.

The reason I was wondering if a servo problem is likely is that I have some E-Sky parts to order before I'll get a chance to do the test (above), and as the servo is common to a number of helicopters I've got, and at ~£8 is comparable to the postage, I was thinking about getting a servo on spec.

I reckon there's a better than 50% chance it's the servo rather than Rx.

[scallybert]

Well, some further observation is at odds with what I thought I previously saw.

It wasn't just one servo glitching, but both rear swashplate servos glitching in unison. Very reproducable, and they both deviate the same amount. It happens when the lateral cyclic pitch is just off-centre.

This changes my guess. Since it's common to 2 servos (and therefore 2 channels ?), it would seem likely to be before the inputs are mixed in the Tx CCPM, related to the stick input itself. ie a Tx problem.

Another weird thing is that the trim tab has an effect. Moving this right of centre seems to have removed the effect. Set like this I did 5-10 minutes attempted hovering, and it behaved ok, and this went ok.

Makes me wonder where to go next. I'm not inclined to spend money on a replacement E-Sky Tx. (This one has hardly had a hard life.)

I guess for now it's doing what I need - I'm learning and having fun with it, etc. (And finding it easier than Phoenix...)