Servo Reverser Harness Initial movement?  
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All Forums >> Radios, Batteries, Clubhouse and more >> RC Radios, Transmitters, Receivers, Servos, gyros >> Servo Reverser Harness Initial movement?
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Servo Reverser Harness Initial movement? - 8/26/2008 3:02:49 PM   
Brainiax



Posts: 225
Joined: 4/10/2007
From: Coventry, RI, USA
Status: online 		Hi, is it normal for the servo on the elevator that is controlled by a servo reverser to move up and down once, quickly, before centering itself upon power-up? Mine does this on a regular basis and I was just wondering if it should be replaced or if it's a common occurrance. Thanks!!

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RE: Servo Reverser Harness Initial movement? - 8/26/2008 4:11:20 PM   
BuschBarber


 

Posts: 823
Joined: 1/7/2002
From: Rochester, NY, USA
Status: online 		What Tx and Rx are you using?

My biggest complaint about Servo Reversers is that sometimes, the Neutral, for the Reversed servo, changes. I have been told that it can be due to heat or other factors. The result is that the Neutral needs to be Reset after a few flights.

I have an H9 P47-150 with a Fuji32ei Gas motor. I was using a Reversing Y harness, from Expert, to reverse one of my Flap servos. Every time I ran the motor, one Flap would Jitter. I put in new Servos and a new Reversing Y harness from Expert. Same problem. It was always the same Flap. It was suggested to me that the Reversing circuit was picking up RF noise from the Engine. I switched to a JR Matchbox and the problem went away.

Are you using a servo for each Elevator half? Are they in a Y harness or on separate channels and mixed? If you have a radio on 2.4, like I do, all the channels go to Failsafe, for a brief second, when I turn on the Tx. If the Failsafe is set to Hold, nothing will move, but if the Failsafe is set to a Preset, like Gear Up, the channel will move to the Preset and then jump back to normal. If I set the Failsafe to Gear Up, my gear will cycle up and down when I turn on the Tx. If I forget, the plane drops on the ground. I always set the Failsafe for Gear, to Gear Down, and it does not cycle like that when I turn on the Tx.

(in reply to Brainiax)
       Post #: 2

RE: Servo Reverser Harness Initial movement? - 8/26/2008 4:51:17 PM   
Brainiax



Posts: 225
Joined: 4/10/2007
From: Coventry, RI, USA
Status: online 		Thanks for the reply. I'm using a Futaba 7CAP (not 2.4) radio with an Extra that has 2 elevator servos (S3010's) and R168Df receiver on 2500mah 4.8v power. My radio won't allow me to use another channel for elevator mixing so i'm stuck with the y-reverser (Expert). It is plugged into channel 2 only. I haven't had any instances yet where it didn't center correctly but it is new also. No other channels are being used other than 1,2,3 and 4. Thanks.

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Damn Gravity Again!!!!!!!!!!!!!

(in reply to BuschBarber)
       Post #: 3

RE: Servo Reverser Harness Initial movement? - 9/2/2008 10:03:23 PM   
maynardrupp


 

Posts: 32
Joined: 8/17/2008
From: Grosse Pointe Woods, MI, USA
Status: offline 		I am using an Expert servo reversing harness on the flap servos for my Sig Waco SRE. The left flap jitters on startup and sometimes assumes a new "up" position. We swapped thebservo leads and the problem goes with the same servo lead. That Expert harness has a potentiometer that is exposed and could be adjusted. Would adjusting that pot somehow clear up the problem? How do you know which way to go and how much.

(in reply to Brainiax)
       Post #: 4

RE: Servo Reverser Harness Initial movement? - 9/3/2008 5:57:45 AM   
BuschBarber


 

Posts: 823
Joined: 1/7/2002
From: Rochester, NY, USA
Status: online 		It is important to state what kind of Transmitter, Receiver, 72Mhz. 2.4Ghz, etc., Servo Type, Battery Type and Voltage, and type of Engine. They all have an impact on the problem you are reporting.

I have a Hangar9 P47-150 with a JR9303 Tx on 72Mhz and a Fuji32ei Gas engine with Electronic Ignition. I was using a JR 5cell 6v NiMh battery. I was using an Expert Reversing Y on my Flaps. When I first fired up the engine, one Flap kept jittering, but not the other. I replaced the servos and the Expert Reversing Y and still had the problem. I replaced the Expert Reversing Y with a JR Matchbox. That stopped the jittering on the Flaps, but I noticed other glitches. I repositioned the Rx and ran the antenna out the top of the Fuse, behind the Canopy, up the Mast, and back to the Vertical Fin. I bundled up the other servo wires and the problems disappeared. I never tried to put the Expert Reversing Y back in, but I was told it might be picking up RF Noise from the Engine, in the Reversing circuit.

I subsequently put a Spektrum 2.4 module in my JR XP9303 and switched receivers to a Spektrum AR9000. Now all the RF Interference was not a factor, but suddenly, my JR791 Retract Servos started jittering. I called Horizon and was told that those servos were not compatible with 6v. When I said that I had been using 6v with my 649 PCM receiver and had no problem with the Retract Servos, they told me they did not know why, but that the AR9000 had nothing to do with the fact that the Retract Servos were sensitive to 6v. They said I should have seen the same jittering, with the Retract Servos, when using 6v with the 649 PCM receiver.

Bottom line is the jittering with your Expert Reversing Y could be due to a number of factors, but I do not know enough about your setup to comment further.

I do know, from experience, that some Reversing Y's and Reversing Extensions, tend to have the Neutral drift every few flights, requiring the servo to be ReCentered, using the Pot. I have had Reversing Y's that did that and I only resorted to the Reversing Y as it was the cheapest attempt to get me in the air. I cannot say that the Expert Reversing Y would have done that, but some of my experience modeler friends recommended I only buy a high quality Reversing Y or Extension. Other options are putting each Flap servo on a separate channel and mixing them( this is what I always do with Aileron and Elevator halves), use Hitec Digital Servos where you can Program them to Reverse and Match one another, or use a Matchbox type device.

(in reply to maynardrupp)
       Post #: 5

RE: Servo Reverser Harness Initial movement? - 9/3/2008 5:18:13 PM   
Rodney



Posts: 4915
Joined: 12/8/2001
From: FL
Status: offline 		I am not familiar with the exact circuitry in your reversing Y but; on most reversing Y's there is a time constant controlled by a capacitor and that adjustable pot. To keep size down, the quality of that capacitor is often a compromise on cost and quality and capacitors are notorious for changing value as temperature changes. This will cause the center position to vary with temperature, sometimes quite a bit. Of course if temperature or vibration makes that pot drift a bit, that can also cause the center point to drift.

(in reply to BuschBarber)
       Post #: 6

RE: Servo Reverser Harness Initial movement? - 9/3/2008 9:10:48 PM   
maynardrupp


 

Posts: 32
Joined: 8/17/2008
From: Grosse Pointe Woods, MI, USA
Status: offline 		My setup is 2.4ghz. Spectrum with a Saito 100 on the Waco Cabin. I have ordered a reverse JR 821 servo. The others are also 821 so I don't anticipate any problems. I just don't want to take a chance of having a problem with that "Expert"reversing Y harness in the air. $40.00 for the servo is less than a matchbox also. If I were to do this again I would swap the arm on one servo and mount the control horn in line with the new servo arm location. There is plenty of support block on the flaps for that. I don't see why that wouldn't work, does anybody else?

(in reply to BuschBarber)
       Post #: 7

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All Forums >> Radios, Batteries, Clubhouse and more >> RC Radios, Transmitters, Receivers, Servos, gyros >> Servo Reverser Harness Initial movement?
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