lvaldes

My Feedback: (2)

I recently purchased a couple of HS 5625 for a Great Planes U Can Do 3D 60. I use them for the individual elevators.

I did the original setup and flew 5 or 6 flights.

Last time, on my preflight check, y noticed one of the elevators had a 30 degree up deflection. Everything works OK but the deflection is offset 30 deg. I fixed the servo arm to center, however, noticed that the up throw was limited to about 10 degrees.

I undid the servo arm movement on the last paragraph and fixed the issue using the sub trim feature on my JR 8103 to its downward limit. Every thing seems back to normal, but I'm really puzzled with this. I did the original setup with 0 trim offsets, now my plane flies with an down offset of 240 in one of its elevators. It seems as if the servo somehow lost its center. Is this possible? I'm kinda new with digital servos.

Thanks!

mglavin

My Feedback: (31)

Sounds like, something has caused the servo to loose its programmed neutral parameter. Moving the servo arm to another spline location is a dead giveaway. Do not fly the model until figure this out! I would reprogram the servo and bench test it with the Hitec programmer to validate its integrity prior to putting it back to work...

How is the model rigged, heavy duty wyes and extensions? What voltage battery?

lvaldes

My Feedback: (2)

mglavin:

Your suggestion makes sense.

I hadn't thought about the rigging.

The 2 Elevator and Rudder servo wires are HD, but fairly long 36!QUOT!+ (the servos are near the tail plane and the Rx is in the CG). No extensions there, I did the long wires myself.
Batt is standard 1100mah JR Extra 4.8v.

I recall some slight accidental movement of the flying surfaces during transportation, I dont know if this could have caused the offset (I doubt it).

Thanks!

mglavin

My Feedback: (31)

If the accidental movement introduced a shock to the control surface this may have a damaged the plastic output gear of the servo motor (the only resin-plastic gear in the servo).

I would definately switch to a 6.0V battery. The voltage realized with the high current demands of digital servos at extreme lead lengths via several battery connections is a problematic. Under start-up loads and general use I have measured a 1.0V drop or better at the servo.

I have been using Hitec digitals exclusevly on 6.0V. since their introduction, I've yet to have a problem.

Sounds like it might be a good idea to return the servo to Hitec for a look inside. It's cheap insurance.

Do you have the Hitec servo programmer?

I noted your in Monterey, do you know Gustavo?

Jemo

My Feedback: (5)

Just a thought here.

You don't by any chance have a knob still activated, that would allow one elevator half to get out of trim by turning that knob. ??????

lvaldes

My Feedback: (2)

mglavin:

I don't think any of the gears are broken, the servo works OK with the huge offset in the TX. I do not have a programmer but know someone that does, I'll borrow it for a day o two. Anyway, I guess I'll replace the servo and send it back.

BTW, I do know Gustavo. Obviously, you do too... Did you visit Monterrey last fall with Joe & Co.?

lvaldes

My Feedback: (2)

Jemo:

I have tried moving every switch and knob in the TX. I did it in the field before the quick fix, and then at home in a more orderly manner with no result yet.

mglavin

My Feedback: (31)

I know of Gustavo via the Pitts forum, I talked with him about coming down. I considered coming down for the event and truly wished we had. But other things and the long drive precluded the trip last year. My son Josh and I are going to make an attemp to make this years event...

Good choice on returning the servo, its cheap insurance if nothing else.