Difference in servo movement question

[Sannan75]

Hi,

Whilst replacing the swashplate on my mCPX BL this morning I noticed that the servo on the left of the frame (looking from the tail to the nose) has a lot less movement for a given control input than both the rear and right hand side servo's. It looks too be moving at about half the rate or just under, is this normal or this that servo playing up?

If it's playing up, is there anything I can do with the existing one to repair it or do I just need to get a new one?

Thanks in advance

[Crumpet]

I would assume the amount of movement would be set by your transmitter. Never heard of a servo being damaged and then not having full range of movement.

All 3 servos should have the same amount of up as they do down, and is usually set using a swash leveller.

I'm fairly new so I'm sure more info will come

[tomatwalden]

Hi,

Whilst replacing the swashplate on my mCPX BL this morning I noticed that the servo on the left of the frame (looking from the tail to the nose) has a lot less movement for a given control input than both the rear and right hand side servo's. It looks too be moving at about half the rate or just under, is this normal or this that servo playing up?

If it's playing up, is there anything I can do with the existing one to repair it or do I just need to get a new one?

Thanks in advance

It's playing up probably. It's fairly easy to check with the mcpx BL. Once you plug the LIPO in and BEFORE you spin up the motor, the servos are under direct TX control, rather than via the FBL gyros.

At this stage, you should be able to move the cyclic and collective to move the swash plate to it's full throw. In particular, full negative to full positive collective should keep the swash plate level at all times.

If not, the servo is knackered. They can sometimes be fixed by cleaning the contacts on the linear servo, otherwise, new servo required.

https://www.youtube.com/watch?v=V0NIepknfnE

[Sannan75]

Thanks Tom (& Crumpet),

I'm pretty sure collective wasn't level throughout the range when I tried it this morning, will recheck to confirm and then will clean before replacing, no harm in trying (great link btw btw).

Edit: The contact strip in the servo is dirty except for a patch about 0.5cm long in the centre, will clean up all servo's and see if it behaves itself after that.

[crash-test-tomo]

I remember a servo on my v2 mcpx not sitting correctly, even after cleaning etc it still for some reason 'thought' center was a couple of mm lower than the other 2. Was an aileron servo so I checked trims etc and still no joy! Flew fine and I sold it that way lol

[Sannan75]

Yeah, I've cleaned all three, just from watching they look to be doing all sorts of crazy stuff now tbh. Tomorrow I'll build it back up, see what the symptoms are once it's built in terms of how it sets itself and responds to controls and go from there. There's no reason for it to have started being odd, it was flying fine, I've put a new swashplate on and noticed the small movement on the servo whilst doing that.

Sodding thing lol.

[tomatwalden]

Make sure you've put them back together carefully. As per the vid, the wiper is quite sensitive. Linear servos are a blessing and a curse. They can take a knock better than similar sized rotary servos, but the contacts get dirty resulting in this kind of behaviour.

[Sannan75]

No new servo needed Before ordering a new one yesterday I decided to swap over the servo's and make sure the issue travelled with it and it wasn't a problem on the board and before doing the swap checked over the controls and all looked fine. Why leaving it overnight without touching it would make a difference I have no idea.

I re-cleaned all the servo's to make sure they were good, did a complete rebuild, rebind and setup and she's flying beautifully

Thanks for the advice and tips, the weirdness kicked in after flight 57 so I've added a maintenance task to clean the servo's every 40 flights.