critch

We live out away from a hobby store (2 hours ) so i am trying to get as much info on the possible problem. I have recently finished a Thunderbug 120. I am using an Airtronics Quasar radio with a hitec rx and servos on the new z connectors. I have dual ailerons and a y harness. The aileron servos connect with an extension to get out of the wing and then I plug into the y harness. When i did the initial range check everything was fine with antennae down with engine on and off everything was smooth. I am using a 1900 mah battery 4.8 with an extension so I can place it near the rear of the plane for balancing. On my first flight (we have snow in NM right now) I landed, lost landing gear (not enough room on it for a wheel collar hit some muddy water (very small puddle but it did create a little splash) which kicked some dirt water on my wing. I thouroughly cleaned my wing and didn't think my servos got dirty from it but who knows. Well anyway I went out for the second flight after getting a little longer landing gear the next day and when I turned on the radio and the aileron servos move a little start, stop, get quiet start up and move a little. When I move the servos they will often times resist going to neutral a little. I have made sure my radio is on the correct settings, I have also unscrewed the servo horns from the servo and this chatter still goes on (one hobby store owner thought maybe the servos were struggling to get to center). But it is not always continuous the chatter will go away and the servos will be silent then they might chatter after moving the aileron. If I unplug one servo the other works fine and if I unplug the other the opposite one works fine. I have tried swapping the wires and plugging in and the results are the same. I have walked away from the plane and have checked the radio and have the same symptoms. These are GWS servos with higher torque output and the y harness is GWS. The extensions are expert (when I assembled the pack everyone seemed out of what I needed). Anyway I had a spare GWS servo and have plugged it in independently and have seen the same results (in tandem with one aileron servo chatter, by itself it is fine). This was my first new z connectors so I don't have another y harness which is what i am guessing is the problem. Someone else also stated that i might want to get a y harness with damper (I think) to help if there is interference. I haven't tried plugging each aileron servo into the rx by itself because the rx is well packed. But that is my guess. I have recharged the plane and have checked again. Every extension connection has a little piece of dental floss tied to ensure that I have solid connections. This was my first experience with the GWS servos and wire but have seen Dick Pettit use some of them through the years. What do you think???

PS It is a long message so excuse my mistakes!

FHHuber

Sounds like you need a filter or booster in the aileron Y, and possibly a larger guage wire on the battery extension and switch harness.

Then again... you could have gotten just a little dirty water into one or both ailerons servos (mounted on lower wing surface with output arm parallel to the bottom of the wing?) If this is the problem.. you need to open the servos and spray the circuitry with a PC (Printed Circuit) board cleaner. Then you'd have to clean and re-lube the gears before reassembling the servos.

There's a simple Y harness booster/glitch buster you can make. I've got one I made about 2 years ago from a diagram found in RCM. One appx $3 chip. In the RX, the circuitry that generates the "position desired" signal for the servo reduces the voltage on that line going to the servo. This circuit boosts the signal line voltage back up to that of the battery. Works slick, makes the servos move faster and smoother. [img]i/expressions/face-icon-small-smile.gif[/img] Allows you to use 36 inch servo extension too.

I'll pull the little gizmo out and draw the schematic up if you want.