Cliff Bastow Posted February 6, 2017 Share Posted February 6, 2017 I had a very odd problem with my Travel Air today. I use Futaba fasst radio, On my second flight, I turned on the model and everything working fine. On starting the engine the throttle now wont work. I stopped the motor and turned off the model to start investigation. First I turned the model back on and throttle works, that is odd I thought so then I moved all the other controls and all working fine. On trying throttle again it does not work. Few more tests and it seems problem is this. On turning on the model the throttle works fine until any other control is moved, then the throttle wont work until the model is turned off and on again. Also if the throttle is left fully open as soon as anything else is moved the throttle goes to fully closed and then wont work. I thought maybe failsafe but everything else is still working. Any ideas please? Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted February 6, 2017 Share Posted February 6, 2017 If the model is electric Cliff, put the throttle trim fully down, and try again Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted February 6, 2017 Author Share Posted February 6, 2017 Hi Dennis, Sorry I should have said its IC and its the throttle servo thats not working sometimes. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted February 6, 2017 Share Posted February 6, 2017 OK Cliff, start with finding out if it is the Tx stick. Or the Rx, as the failsafe is in the Rx, Or the Throttle servo, where you plug in another servo to the THR socket on the receiver Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted February 6, 2017 Author Share Posted February 6, 2017 The transmitter I use, has the moving bars that show what is happening and all is working fine on all channels even when the throttle does not work so I dont think its the tx. Plus I flew 2 other models today with no issues. I cant see that the rx has gone into failsafe as all other channels still work fine. I have not had time yet to check connections. Quote Link to comment Share on other sites More sharing options...
Phil Green Posted February 6, 2017 Share Posted February 6, 2017 Besides the usual loss of signal failsafe, Futabas often have what they call a 'battery failsafe' which shuts the throttle if the receiver battery is low. It could be the cause, at least its something else to look at: **LINK** Quote Link to comment Share on other sites More sharing options...
kc Posted February 6, 2017 Share Posted February 6, 2017 Maybe the throttle is stiff and the battery cannot provide enough amps while the other servos are working. Could be lucky this may have revealed a problem that would be fatal once airborne? Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted February 6, 2017 Author Share Posted February 6, 2017 Thanks Phil, its certainly worth a look. Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted February 6, 2017 Author Share Posted February 6, 2017 Hi Kc. I dont think there is anything wrong with the linkage, as the model has had over a hundred flights with no problem but I will check. Its not that the throttle wont work whilst other servos are working. The throttle works fine, then move any other control and release, now the throttle wont work at all untill the model is turned off and back on again. same happens everytime. as soon as any other control is moved then released throttle will no longer work. Very odd. Quote Link to comment Share on other sites More sharing options...
.. Posted February 6, 2017 Share Posted February 6, 2017 What model transmitter is it Cliff? Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted February 6, 2017 Author Share Posted February 6, 2017 its an 8 FG super Justin. Quote Link to comment Share on other sites More sharing options...
.. Posted February 6, 2017 Share Posted February 6, 2017 Ok , I use a 14 SG and it seems similar programming. Are the recievers on the other planes the same ? It sounds odd , almost like the movement of the other sticks is somehow putting the throttle into "INH inhibited mode"? Personally with it being a fairly simple model radio control wise I think I would make a note of any trim positions & erase the program then open a new one. Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted February 6, 2017 Author Share Posted February 6, 2017 Hi Justin, I had thought along similar lines but as I mentioned, if you go into the servo monitoring page on the transmitter it still shows the throttle as working. You know the page with the moving bars when you move the sticks? Surely this would not be so if the throttle was inhibited? One of the other rx used today is the same. they are R617FS. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 6, 2017 Share Posted February 6, 2017 Phil's theory seems the most likely. If a cell has gone bad in the pack, the off load voltage may be enough to power the receiver when fully charged but when you start moving several servos may drop below the threshold to activate the battery fail safe. In this condition, only the throttle servo should be disabled and all other channels should respond. Check the receiver battery voltage - if it's lower than the high 5.ns fully charged you probably have at least one failed cell - typically they fail short circuit so a fully charged battery in the 4.ns is a good indication. If you don't have a voltmeter then try a battery from another model. Edit - Just seen the last post - remember that without telemetry, your transmitter doesn't know if the battery failsafe has operated - it keeps sending the throttle commands but the receiver ignores them... Edited By Martin Harris on 06/02/2017 16:52:43 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 6, 2017 Share Posted February 6, 2017 Cliff "Surely this would not be so if the throttle was inhibited?" As a matter of pure logic just because the Tx says the throttle is moving it is unwise to assume that it is actually sending the radio signal. The only sure way to identify what is causing the problem is by logical substitution. If it does the same with a different Rx installed then the issue is with the Tx and so on. Quote Link to comment Share on other sites More sharing options...
kc Posted February 6, 2017 Share Posted February 6, 2017 I was thinking that the throttle might use a snake which has got gunged up and causing extra friction. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 6, 2017 Share Posted February 6, 2017 Posted by Simon Chaddock on 06/02/2017 16:57:37: The only sure way to identify what is causing the problem is by logical substitution. I think you'd do well to start with the receiver battery... Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted February 6, 2017 Author Share Posted February 6, 2017 HI Simon, I am not assuming the TX is actually transmitting, I am just saying that if the TX says the throttle is moving then surely the TX cant be in throttle inhibited mode? You are correct about logical substitution. I don't have time to try anything today but I think maybe Phil could be on to something so I plan to try an new Rx pack first. Quote Link to comment Share on other sites More sharing options...
MattyB Posted February 6, 2017 Share Posted February 6, 2017 Probably a bit too much theory in this thread guys(!) - simply check the batt voltage under load, and if that looks ok out ok plug a different servo into the throttle channel and see if that works. No point doing any further theorising til those simple tests are done. Edited By MattyB on 06/02/2017 19:32:54 Quote Link to comment Share on other sites More sharing options...
CARPERFECT Posted February 6, 2017 Share Posted February 6, 2017 Just try selecting a different model on the tx. ? servos might be the wrong way round but if problem still there throw the servo in the bin. Quote Link to comment Share on other sites More sharing options...
Nigel Grant 1 Posted February 7, 2017 Share Posted February 7, 2017 I use an 8fg. If you look in the manual, pg 64 on failsafe it describes that the failsafe can be set for both transmitter signal and also Rx battery. So if your rx battery is getting tired and you lose your voltage when you operate the other servo's, depending on how it has been set up, the throttle channel/servo will go to idle and wont operate again. Till you restart the system. Sounds like that could be worth checking. The matter is also dealt with in Malcolm Holts excellent supplementary notes on the 8fg super which can be found on google as a free down load. If you haven't got this let me know on this thread and I'll find the link and post it tomorrow. Nigel Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted February 7, 2017 Author Share Posted February 7, 2017 Thanks to all for your help. It was the rx battery a bit low and the battery failsafe cutting in as described by Phil and Nigel. This cuts out the throttle if the battery gets too low. I was not even aware that some Futaba rx had this facility. I think the throttle worked ok as its just a standard servo so did not drag the battery down so much but because the other servos are digital they draw a bit more and dragged the battery down enough to cause the battery failsafe to cut in. New battery fitted and all ok. Quote Link to comment Share on other sites More sharing options...
Phil Green Posted February 7, 2017 Share Posted February 7, 2017 Quote Link to comment Share on other sites More sharing options...
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