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Futaba 6xa troubleshooting

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Old 11-27-2012, 02:09 PM
  #1
2wheelfiddler
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Default Futaba 6xa troubleshooting

Hi,
I'm new to RC planes but my equipment isn't!
Back when I was a kid, I built a Hangar 9 Easyfly 40 trainer plane with my dad, but I never got to fly it.

After letting the plane sit in my father's workshop for roughly 10 years, I've decided to learn how to use it, because I finally found someone who can show me how to fly it.

My problem is: Although the batteries are good in both the remote and the receiver, when I move the sticks, the servos don't move.

I've tried some troubleshooting of my own and here's what I can say:
- The batteries in the remote are good, they stay over 10V for more than an hour and the low battery warning comes on at 8.5V
- The receiver battery, a 4.8V unit, seems to be good too. When I hook it up to the receiver, the 4 servos on the plane twitch, which tells me there should be enough power to respond to commands from the remote.

I haven't tried the engine yet because the receiver doesn't respond, obviously, but I also need to get a new 12V battery to run the starter motor and the glowplug warmer.

Any idea why the receiver won't respond to the remote? I checked and they both have the same frequency crystal. 72.910 if I remember correctly.

Any help would be greatly appreciated!

Félix.
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Old 11-27-2012, 02:20 PM
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Default RE: Futaba 6xa troubleshooting

it's absolutely possible the airborne battery has enough juice to make the servo's jiggle, but not enough to fully power up the receiver and keep it powered.... I'd suggest fully charging both batteries for at least 8 hours and giving it another whirl
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Old 11-27-2012, 02:50 PM
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Default RE: Futaba 6xa troubleshooting

Check the modulation. Here is a link to the manual:
http://manuals.hobbico.com/fut/6xas-hs-manual.pdf
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Old 11-27-2012, 03:00 PM
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Default RE: Futaba 6xa troubleshooting

Joe: Please keep in mind that this is a beginners forum. Modulation might mean something to you, to me, and to others here, but probably not to a beginner. Please keep replies in perspective.

CGr.
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Old 11-27-2012, 05:41 PM
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Default RE: Futaba 6xa troubleshooting


Quote:
ORIGINAL: CGRetired

Joe: Please keep in mind that this is a beginners forum. Modulation might mean something to you, to me, and to others here, but probably not to a beginner. Please keep replies in perspective.

CGr.
Sure thing!

The radio in question has the ability to communicate in two different languages, which we call modulation. The two languages are PPM and PCM. You can read more about this on p. 40 of the manual I linked. It is possible your receiver is expecting to hear PPM, while your radio is talking in PCM. Try both 'languages' and see if it helps.

Your servos jittering when power is applied but not responding to the radio sounds like the communication is not happening. It could be a problem with the channel or crystal, it could be a bad receiver, a problem with the radio, or something simple like a modulation setting.

Hope this helps!
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Old 11-27-2012, 06:51 PM
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Default RE: Futaba 6xa troubleshooting

Oh yeah,
I have the manual and indeed when you talked about modulation I was a little confused, but yeah, I did see something about PCM and PPM. I actually thought it might be something like this because I read the transmitter could work in FM or some other signal.

As for the receiver battery, I didn't have my voltmeter to check it but it was charged for as long as the transmitter, so I just assumed it was ok. I'll look into these two possibilities.

Thanks for the replies.

By the way, is there any way to check if the remote is working correctly? If it does and the problem is the receiver, can I just change the receiver and keep the same remote and servos?
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Old 11-28-2012, 06:55 AM
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Default RE: Futaba 6xa troubleshooting


Quote:
ORIGINAL: 2wheelfiddler
By the way, is there any way to check if the remote is working correctly? If it does and the problem is the receiver, can I just change the receiver and keep the same remote and servos?
there isn't an easy way to specifically check if the trans. is working properly or not without swapping out the receiver, transmitter or both....
but, as long as the replacement receiver is compatible with your transmitter, on the same frequency and Modulation (as was pointed out :^) ) you can use the same transmitter, servos etc with a different receiver.
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Old 11-28-2012, 08:49 AM
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Default RE: Futaba 6xa troubleshooting

Well thanks for the info!
I know a guy who has been in RC planes for long enough that he should have a FM remote/receiver that I can do tests with.
I guess all I need to do is make sure I have the same frequency crystal?
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Old 11-28-2012, 09:04 AM
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Default RE: Futaba 6xa troubleshooting

As long as your friend's receiver is either Futaba or Hitec brand, then just make sure the crystals match. Your Futaba transmitter will not communicate with Airtronics or JR brand receivers. Now, assuming that your friend's receiver is Futaba but on a different frequency (different crystal number) you can pull the crystal from your receiver and plug it in to his receiver and test. It is legal to change crystals in the receivers but not in the transmitters.

There are a myriad of other possibilities, but let's start simply and work toward a solution. I am betting on a bad receiver battery. That is the most likely suspect and the easiest to isolate and fix.

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Old 11-28-2012, 09:04 AM
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Default RE: Futaba 6xa troubleshooting

yupper, that should do it...
I looked at the manual (link) provided by gaRCfield ....
the TX should display on the LCD screen if it's set to PPM (PROBABLY what you want) or PCM.
I probably should have asked earlier... what receiver specifically does the airplane have? (it may well say on it PPM or PCM)
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Old 11-28-2012, 09:34 AM
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Default RE: Futaba 6xa troubleshooting

ooops, my bad. I thought he said he had already checked that out. That would be the first thing to check.
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Old 11-28-2012, 12:04 PM
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Default RE: Futaba 6xa troubleshooting

why not just try all new batterys then go from there
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Old 11-28-2012, 04:28 PM
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Default RE: Futaba 6xa troubleshooting

All very good info guys.
I will have to check to make sure I'm on PPM but I think I am. My receiver is a FP-R127DF, it's FM
I thought of changing the batteries right away, but since they seemed to still be good (the one in the remote is) I suspected the receiver was fried. Then I thought, why buy new batteries if I end up having to get a new receiver that may not use the same batteries anyway.

Impressive amount of feedback guys, I really appreciate it. I'll check my battery with a voltmeter this weekend so I'll know for sure.
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Old 11-28-2012, 05:01 PM
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Default RE: Futaba 6xa troubleshooting

Hi there,

I would strongly recommend you replace both batteries completely, whether or not they hold a charge. Don't forget, if you loose the engine, you can land, but if your battery goes, "That's all for now, folks".

I normally replace mine every three or four years just to be safe.

As for your problem, I had a similar situation a few months ago. Batteries checked out, crystal was good in both the transmitter and receiver, and all the wires were good. It turns out that the antenna had failed at the solder joint, so all I would get was a glitch at startup. You could also have a faulty wire somewhere - try bypassing the battery straight to the receiver; remove the switch harness all-together to eliminate that as a cause. If nothing still works, try wiggling the plugs a bit - this could reveal a loose wire as well.

Hope this helps,

Graeme
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Old 11-29-2012, 04:35 AM
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Default RE: Futaba 6xa troubleshooting

Do what Graeme suggested. I did essentially the same thing you did. I let my 6XA sit for about 10 years. I ordered a new TX and RX battery before I did anythnig else. It's a great system, and just about everyone at my field is on 2.4. I pretty much own the frequency board.
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Old 12-03-2012, 08:47 AM
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Default RE: Futaba 6xa troubleshooting

What good does it do to "OWN" the frequency board when all of the others can still fly whenever there is a spot open on the flightLine?
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Old 12-03-2012, 10:25 AM
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Default RE: Futaba 6xa troubleshooting

I switch back and forth from 2.4 to 72 and it's good to own the board these days but I still have to walk the line, there are two other pilots that still fly once in a while and we are all on 15, it's worth the walk in my case. I have been fooled by the modulation thing a few times, I still have several planes on 72 and one is on PCM and when I change planes I forget to turn my radio on and off to cycle it.
By all means go buy some new battery packs, after 10 years they may hold a charge for a while but they can go down very fast too. I take in my old packs to Batteries Plus and have them make up new packs for me. It's worth the price just to be sure.
I lost a plane last year and knew it was my radio having a problem, sent it into Radio South for service and my antenna was not making good contact so one minute all was fine and the next minute my plane was flying itself.
There can be several problems your system is encountering and it would be a good idea to let your instructor go through your system to try to locate it. On line help is pretty good but hands on would be a lot better.
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Old 12-03-2012, 10:31 AM
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Default RE: Futaba 6xa troubleshooting

10 years of sitting around?? If the new batteries don't produce a rock solid system the send it to a GOOD repair shop for evaluation and repair. Corrosion and such can retune a unit as can individual components drifting in value just due to age. Fly something risky - if you can afford a new plane.
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Old 12-06-2012, 12:07 AM
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Default RE: Futaba 6xa troubleshooting

I would say that if your Tx remains on, you have a good battery

Servo twitch doesnt mean anything. I would try and loan a known working battery from a fellow flier and plug that into the RX and then check. That way you dont spend.

I may be wrong, but I think the 6EX works on PCM mode. Just check because I used to set mine to PPM when I used it on the sim I think. Its several months since I sold the 6EX so I am not sure. The 6EX doesnt come with a replacable module, so that wouldnt be a problem. Make sure you are on PCM mode. But if it doesnt work, try PPM also. You can research your RX on Tower and find out which mode it requires

If all else fails, gently pull out the crystal from the rear of the TX. It plugs in just like a USB drive but the metal pins are delicate, so be careful. Check for oxidation on the pins. Same on the RX

Oh yes, try to extend your antenne and see if that helps.

Check for breaks in the white antanne wire that comes out of your RX

If all of this checks out, you have probably checked all that you can do. The you need to take it to a proper service centre for a checkup. Futaba has good service support in the US

Ameyam
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Old 12-06-2012, 10:33 AM
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Default RE: Futaba 6xa troubleshooting

If the batteries are original to the radio or more then 5 years old, be safe and change them out. They may take a charge and hold it for a bit, but I wouldn't rely on them staying that way. I just lost a club trainer due to the donated battery pack (history unknown) shorting out which caused the plane to spiral down and re-kit itself. Once my batteries hit 5 years old I'll change them regardless of how much charge they hold and for how long. I've seen too many older batteries that checked good short out for no reason.

I've had really good luck with batteries from Canuck Engineering out of Colorado. Sanyo 2000mAH Eneloop packs: $33.00 for a TX pack, $22.00 for a 6v (5-cell) receiver pack. After the first of the year I'll be ordering a few packs again from him. Eneloops are nice as they will hold a charge sitting on a shelf a lot longer than standard NiMh batteries.

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Old 12-06-2012, 12:58 PM
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Default RE: Futaba 6xa troubleshooting

Well guys, thanks for all the replies.
I'm a member of a few forums for my motorcycles and I rarely get so much feedback!

I found a guy who was old enough to know how a good old FM radio works and we found out my receiver was the problem. He used one of his, with my crystal and everything worked out.
Thing is, this plane has been sitting for years, so although the engine started up just fine, once in the air it kept stalling and we had to land it in "glider" mode.

We've thorn the engine appart to clean everything up and it should be flying good this weekend!

Thanks again for all the info!

Felix, from Quebec, Canada.
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