7980th end point adjustment

[Trainee]

Hi all,
Just getting my superclass crawler finally finished up and I am having a terrible time getting the servos to work like I want. I have a Futaba 4PL and dual Hitec 7980's front and rear. With everything together it works great and I had full left and right steering with both the front and rear servos, but the steering was off center. The Airwild servo arms, no matter how they were installed on the servo, were one cog off of center. Instead of taking the easy way out and adjusting the draglinks, I bought the Hitec HPP 21+ to reprogram the center point of the servos. The centering part went fine and works great, BUT now both servos only go about 75% of the way left or right when I plug the servos back to in to the receiver & use my radio. I even programmed the left and right points to the max after resetting the new center point. When I put them in test mode on the Hitec PC program, they sweep all the way to the lock in both directions. I must be missing something here!! I've been trying to figure this out for about 3 hours. When I erase the new center programming, the servos do work normally.

Sorry so long, just wanted to cover everything I've done.

Any help would be GREATLY appreciated!

Frustrated in Fargo. :/

John

[jado6006]

Am i understanding that instead of popping the horn off & centering it, your going thru this? Tell me i got this wrong!

[meatmonkey]

I'd think you need to return the servo's neutral to stock and simply adjust the trim on your fancy radio. If the trim doesn't have enough range of adjustment then try using the "sub" trim as well.

The biggest advantage to the programmer is that you can set the "overload" protection, and slightly open up the neutral deadband. Both of these things will help to lower servo temp and extend servo life.

[nharkey85]

Originally Posted by jado6006

Am i understanding that instead of popping the horn off & centering it, your going thru this? Tell me i got this wrong!

its not exactly that, with the servo "centered", its splines and the horn's splines dont make his steering "centered" the simplest fix is trim/subtrim adjustment on the radio.

and someone with a fancy radio can correct me if im wrong but...

trim = adjusting center point only

subtrim = adjusting center point and epa equally in the same direction

[Calderwood]

What do you have the 4pl endpoints set to?

Originally Posted by jado6006

Am i understanding that instead of popping the horn off & centering it, your going thru this? Tell me i got this wrong!

The air wild horn is about a foot and a half long so one spline moves the horn more than he needs. He said the sweet spot was between splines.

[Trainee]

I have all the end points at 100%. Like I said before, when I clear the programming of the new center point and make it like it was before (stock) the steering does go lock to lock on the knuckles. That's why I believe it's something in the programmer settings I'm not seeing.
I could adjust the front to 120% on the trims and get closer to what I need for the front, but can't do that on the rear. Still, it's not right. I shouldn't have to do that. Right now I'm only getting about 30 degrees of movement out of this servo after resetting the center to where I want it. (which was only about 2 degrees off)

John

[Calderwood]

Originally Posted by Trainee

I have all the end points at 100%. Like I said before, when I clear the programming of the new center point and make it like it was before (stock) the steering does go lock to lock on the knuckles. That's why I believe it's something in the programmer settings I'm not seeing.
I could adjust the front to 120% on the trims and get closer to what I need for the front, but can't do that on the rear. Still, it's not right. I shouldn't have to do that. Right now I'm only getting about 30 degrees of movement out of this servo after resetting the center to where I want it. (which was only about 2 degrees off)

John

What are you programming the travel to?

[Trainee]

When I program the travel, I max out on the slider at 47 or 48 both left and right and save those points. After doing that, I run the sweep test and it DOES go lock to lock on the knuckles, but not when I unplug the programmer and plug the servos back into the receiver to control them with the radio.

To me it would seem it has something to do with the programmer and not the radio settings, but for the life of me can't seem to understand it. I have read and reread the instructions to no avail. I might have to call hitec tech support Tuesday.

[Trainee]

Just figured it out! If I take off the drag link and THEN program the servo with the bare arm, it allows me to turn it up past the 47/48 I was limited to before. It took about 10 tries, but I found that 64 works best for my application, both left and right. That just maxes out the knuckles. Then i set the overload protection to 50%.

Hopefully this helps someone out with a similar problem.

John