Stephen Tye Posted March 23, 2015 Share Posted March 23, 2015 I'v noticed my servos are twitching on their own accord...this happens when i switch on but sometimes it doesn't and can happen sporadically during a test. Any Ideas of the cause?.. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted March 23, 2015 Share Posted March 23, 2015 Jittery servos are bad news! Is it all of the servos that are twitching - or just one? Is it the same one? If its all of them - its probably some source of interference or noise - could the metal-to-metal generated RF for example. Is the engine running when it happens? If its one servo then most probably its a fault with that servo or the lead - most likely the servo. If its interference you can try to locate and eliminate it. If its a dodgy servo then the only solution really is to replace it. BEB Quote Link to comment Share on other sites More sharing options...
Dane Crosby Posted March 23, 2015 Share Posted March 23, 2015 Hi. Are the Servos digital? Do you have a stability system such as A3X? In these cases the servos can hunt a bit. Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 They'r not digital servo's and its all of the servo's twitching even without the engine running... Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 I will fit a new set of servo's and see if there's any difference.. cheers!.. Quote Link to comment Share on other sites More sharing options...
kc Posted March 23, 2015 Share Posted March 23, 2015 First you should check that the Rx battery and Tx battery are fully charged and giving their correct voltage. Tell us more about the model and how you test it - at the field or indoors? With other models around? What radio gear and new or old? 2.4 or 35 mhz? Electric power or glow? If electric whether ESC or separate battery? Has the model flown OK or is it just being prepared? I saw your video and noticed the power panel......is that near and switched on? Edited By kc on 23/03/2015 17:15:31 Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 Radio gear is Futaba 7CAP/7CHP TX, Receiver is Futaba R168DF (FM) 35 mhz and servo's are NES 507. The servo's were in the plane when i bought it but the RX/TX i mention came together in the box as new. I'v still got the matching servo's in the box as i realize it could be a servo incompatibility issue so i could fit them.. Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 I test it in the yard at home as seen in the video or without the engine running in the house... cheers!.. Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 Its a Chart Mascot trainer and i have an Irvine 46 engine fitted in the plane at the moment.. electric doesn't really interest me... Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted March 23, 2015 Share Posted March 23, 2015 If all the servos twitch then it is unlikely to be the servos - unless all of them spontaneously decided to go awol! Very improbable. So I don't think changing all of them will make much difference. Your problem then probably lies elsewhere - do you have a spare Rx you could put in? If that doesn't help I'd be looking at the switch harness and the battery. How about the aerial - fully run out? That's important on 35MHz BEB Edited By Biggles' Elder Brother - Moderator on 23/03/2015 18:12:20 Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted March 23, 2015 Share Posted March 23, 2015 Have you got the right XTAL in the receiver? The rx is Dul Conversion, what colour is the xtal? Quote Link to comment Share on other sites More sharing options...
kc Posted March 23, 2015 Share Posted March 23, 2015 Oh its 35 Mhz ......so check to see if the aerial is run very close to the servos - could well be the cause. Aerial needs to be away from the servo case and of course extended. If you have brand new servos available then it would be best to use them if they are a direct fit. Keep note of the arm lengths for each servo and keep the same for a start. ( arm might or might not fit the other servos exactly) Edited By kc on 23/03/2015 18:20:32 Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 The servo's do their twitching thing even without the TX switched on Quote Link to comment Share on other sites More sharing options...
kc Posted March 23, 2015 Share Posted March 23, 2015 That's normal at home, at the field anyone else's 35 mhz Tx will probably make them jitter far worse and jam. Actually if just one servo is exchanged it might prove something - obviously the aileron extension lead is the easiest way to do this. In Stephen's other thread the video shows considerable vibration which might just have wrecked all the servos at once but it's not very likely! Edited By kc on 23/03/2015 18:29:46 Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 Not sure what an Xtal is Paul, pretty new to this Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 The engine vibrates like this only at low rev's Quote Link to comment Share on other sites More sharing options...
kc Posted March 23, 2015 Share Posted March 23, 2015 Rx and Tx need a crystal if 35Mhz and they need to be the same frequency - check the number written on them. See handbook for location of crystals and be careful not to bend the pins. A dual conversion Rx says so on the case and needs a dual conversion crystal in Rx. Tx uses a normal crystal of the same frequency. Quote Link to comment Share on other sites More sharing options...
kc Posted March 23, 2015 Share Posted March 23, 2015 Rx and Tx need a crystal if 35Mhz and they need to be the same frequency - check the number written on them. See handbook for location of crystals and be careful not to bend the pins. A dual conversion Rx says so on the case and needs a dual conversion crystal in Rx ( marked on Rx crystal). Tx uses a normal crystal of the same frequency. MAKE SURE YOU UNDERSTAND HOW YOUR CLUB USES FREQUENCY CONTROL! Edited By kc on 23/03/2015 18:38:02 Edited By kc on 23/03/2015 18:38:56 Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 Both the TX and the RX have a ch. 66 crystal Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 I wouldn't have thought they would even connect otherwise Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 But thanks for the advice i will check it all out Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 I did take a look at a club, went down there and had a chat and read the rules.. etc but so far I'v just got the BMFA Senior Membership £32. The rest is just testing so far Quote Link to comment Share on other sites More sharing options...
Stephen Tye Posted March 23, 2015 Author Share Posted March 23, 2015 And simulator Quote Link to comment Share on other sites More sharing options...
kc Posted March 23, 2015 Share Posted March 23, 2015 The important thing on 35mhz is that you can crash someone elses plane if you even just switch on when they are using that channel. And they can crash you! So strict frequency control is needed. In most clubs this has become rather lax due to 2.4ghz being used so much. So you must be vigilent and look for anyone else with a long Tx aerial. Of course the other thing to remember is to extend the Tx aerial just before flying. The crystals need to be in the correct part - TX crystal in Tx and Dual conversion Rx crystal in a Dual conversion Rx. Quote Link to comment Share on other sites More sharing options...
kc Posted March 23, 2015 Share Posted March 23, 2015 I notice that the Tx has to be set for PPM or PCM to match the Rx. Has that been done? See page 27 of the manual Quote Link to comment Share on other sites More sharing options...
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