perplexing problem
 

I have encountered a problem that is driving me bonkers. A friend gave me an 80 inch Midwest Extra 300S some time back that needed some TLC. All radio gear had been removed from the plane except for the two servos in the wing which are Futaba S9101 servos. One of the first things I did was test those servos with a servo tester and they worked fine so I gave it no more thought. I recovered the wing and was reassembling everything when it came time to test the ailerons for proper throw. I am using a Futaba 7C transmitter that has never had any issues. I plugged the servos in to a new Futaba receiver and they did not work. I re-tested them with the servo tester and they work fine. I plugged some other servos in to the receiver, some S3151 and some S3001 and they work fine with the transmitter. I replaced the receiver with a known good FrSky receiver and the servos in the wing do not work. I have run out of ideas of where to look for the problem. Everything seems to work fine except those S9101 servos will not answer the signal from the transmitter. Anyone have any ideas?

Are those servos on a "Y" harness? If so, they may be loading the signal line from the receiver to a level below what the servos need to work. You might try them individually to see if they work. If not on a "Y" harness ..... I'm out of ideas other than buying new servos. Those were good servos in their day though a bit small and delicate for the task on that size of airplane. They've been out of the Futaba product lineup for at least 10 years so they're getting a bit old.

Do any other servos work OK with the RX?
With my servo tester, is possible to connect it in series with a servo, and monitor the RX signal to the servo.

Do any other servos work OK with the RX when the aileron servos are still connected?
Do other servos work when connected to the RX aileron channel?
With my servo tester, is possible to connect it in series with a servo, and monitor the RX signal to the servo.
Are there servo wire extensions in the wing?

Let me answer the questions in the order they were asked.
They are not on a "Y" harness. They are connected to ports 1 an 6 in the receiver with flaperons enabled. I have any number of other airplanes with this setup and it works ok. I even went so far as to try another airplane set up this way with the transmitter set on the Extra 300S that I am having a problem with. Futaba transmitters will do this as they are not model specific. The ailerons on the Four Star Sixty that I tried worked fine.

Other servos work ok with the receiver. I plugged several in with them just sitting on the bench to test and both Futaba and JR servos worked fine. They were connected to receiver ports one and six when I tried them.

I have not tried to see if other servos in the plane work with the aileron servos still connected. I will try that.

I assume there are servo extensions in the wing, either soldered or using connectors, but they are in a tube. I have not opened the tube to check how they are connected. But the servos work ok with a servo tester, so I assume there is no problem with the extensions.

I am using a brand new 6 volt battery for the receiver and am getting 6.38 volts at the receiver.

Why flaperons? :( I use channels 1 & 6 with Futaba, but only use flaperons with a 4-servo wing on Ultra Sticks and the like.

Are the other servos working with the same aircraft selected? Odd failure if so. Make sure nothing's inhibited (INH) also.

You posted in "flying giants" and no mention of this problem. I'm not a Futaba user however your installation is incorrect and as "eddieC" said use channels 1&6. If the servos' work on a tester than they are operational and the only thing left is the extension leads. Word of wisdom is never use and off brand lead unless they are custom made.

How do you guys set up the radio using channels one and six for ailerons without using flaperons? Is it possible to slave six to one?

flycatch, the servos were operating with the servo tester through the extensions.

http://www.rcgroups.com/forums/showthread.php?t=1102159 This should answer your questions

Exactly how old is this plane and the servos inside? I had a problem similar once with a plane I built in the early 90s and my aileron extensions had a noise filter device built in which was basically a 7400 series buffer, which happens to run off of 4.8v (5v). When I upgrade my radio and switched to 6v batteries the servos would not work at all with 6v. Removed the filter and all ok.
This may not be your problem.

Jolly Popper, Sometimes when I just want to check to make sure the problem isnt with my Rx, I will plug the servos in question into a different channel.. In this case probably into the throttle and rudder channels, just so I can wiggle one stick to see if I am getting a response from the servos.. that can help narrow down the problem from the servos to either a problem with the Rx, or the programming in the Tx.

Craig.

Stupid question for the original poster. Have the old servos had the tab trimmed out? In other words is it possible that the servo connections are 180 degrees out? If so they won't work.

Glenn

Maybe this has something to do with it.
http://www.futaba-rc.com/faq/faq-receivers-q1060.html

He didn't say what receiver he uses but did say it was a T7C transmitter and that bulletin seems to be associated with a 6014 receiver which I don't believe he is using.

Check the rates for each servo ibn the flaperon screen. It normally defaults to zero and you have to set the perecent of movement. Run the rates up to 100% for each servo , each direction.

Thanks to all you guys who have chimed in here. I will now muddy the waters even more. I was fooling with the transmitter trying to link ailerons (which were not working) with rudder so that just a simple ailerons stick move would give some rudder. Something I did made the ailerons work, but only with flaperons enabled. I have no idea what I did, but they now work if flaperons are on. I still have not figured out how to slave one channel to another. I want to slave channel 6 to channel 1 so that I don't need flaperons. And I want to slave channel 5 to channel 2 to operate the two elevator servos. By the way, I am using a seven channel FrSky receiver, that I took out of another plane and I know is good and all new servos except for the two servos in the wing. I do understand that those servos are old and probably need to be replaced. Even if they were new, they are a bit anemic for this size plane. But more than than, I want to figure out how to operate the more complex features of this radio. So far I have not been able to slave one channel to another and achieve the desired results. And I don't know why the ailerons did not originally work and now they do.

http://www.futaba-rc.com/faq/faq-7c.html Have you visited this?

Jolly, The S9101s are rated for 4.8 volts ONLY. Anything higher will damage them. Dan.

I challenge this statement. Do you have that in writing from an official spec from Futaba?

S9101 servo specifications here.

http://www.servodatabase.com/servo/futaba/s9101

Thank you. It didn't say anything about damaging them at 6v.

And the ServoDatabase has torque and Speed ratings listed for 6.0 volt operation!

Craig.

The S30, S130, S5101 and S9101 are all good servos and share the same case. They have been around since the .60 engine size days and have changed electronically over time but they are all the same physically. That is why the have had such a long lifetime. Unfortunately, they were designed when receiver packs were four cells and nothing else. That website is not a Futaba website. What is posted there has no validity. Your best bet is to send Futaba an email and see what they say. Since the S9101 is discontinued, I doubt that you will receive a reply. From my own experience I have fried two using a five cell pack. Luckily one was on the ground. The second one was not. After that I changed back to four cells. I did send Futaba a letter and they advised me not to use a five cell pack. I’ll try to attach an image of there packaging that was used and you will see that it does not mention anything about voltage. That is because at that time there were only four cell packs being used. Dan.http://www.rcuniverse.com/forum/atta...mentid=2008460

Wow, I used a bunch of 5101 and 9101 on 5 cell NiCd / NiMh batteries. They have all been retired now but worked flawlessly for well over a decade. IIRC and that is a big if, I'm sure I read at the time where they were good to go with 6V. I only retired them because I wanted faster, higher torque servos.

Yep, I'm still using S5101 servos on one plane and have been using 6V to power them for several years.