Andy J Posted July 23, 2023 Share Posted July 23, 2023 Acquired a pair of SuperTec S03 servo in an old model, one of which is exhibiting a very strange behaviour. Both servos are fed on a long Y lead in a 91 inch wing. One servo operates normally but the other jerks around when commanded. Yet when I disconnect the good servo the bad servo operates normally. It almost seems that the good servo somehow affects the other. Anyone have any suggestions as to what may be the issue? Y lead appears to be quite a thick gauge of servo wire so don't think its a volt drop issue. Yet to try a different Y lead to see if that is the issue. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted July 23, 2023 Share Posted July 23, 2023 It looks like the signal from the receiver isn't powerful enough to operate both servos together. The "good" one probably has a lower threshold signal voltage so it works OK when both are connected but the "bad" one will only operate on its own when no other servos are helping to pull the signal down. Try connecting them to different receiver output channels, If this is not possible you will need a signal booster. 2 Quote Link to comment Share on other sites More sharing options...
John Wagg Posted July 23, 2023 Share Posted July 23, 2023 Swap the "Y" lead connections over between servos. If the 'fault' moves over then suspect the Y lead. Quote Link to comment Share on other sites More sharing options...
Andy J Posted July 23, 2023 Author Share Posted July 23, 2023 At the moment both servos are being driven by a servo tester, so don't think its a signal issue. Will try a replacement Y lead but it will be a major issue to replace as the original is built into the wing. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted July 23, 2023 Share Posted July 23, 2023 26 minutes ago, Andy Stephenson said: It looks like the signal from the receiver isn't powerful enough to operate both servos together. The "good" one probably has a lower threshold signal voltage so it works OK when both are connected but the "bad" one will only operate on its own when no other servos are helping to pull the signal down. Try connecting them to different receiver output channels, If this is not possible you will need a signal booster. Yep, probably the position signal isn't strong enough to support these 2 servos, but if your rx has enough channels then just remove the Y lead and plug them into separate channels. 1 Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted July 23, 2023 Share Posted July 23, 2023 (edited) The question is, have you tried it on a receiver? It's still possible that the signal from a servo tester isn't either strong enough or giving the correct signal thresholds to match the "bad" servo. Edited July 23, 2023 by Andy Stephenson Quote Link to comment Share on other sites More sharing options...
Mike T Posted July 23, 2023 Share Posted July 23, 2023 I don't normally have (or air) prejudices about servos, but after your investigations are concluded, I would definitely ditch the Supertec servos, in any event... Quote Link to comment Share on other sites More sharing options...
Shaun Walsh Posted July 23, 2023 Share Posted July 23, 2023 Someone else with a problem with these servos 20 years ago. https://www.rcuniverse.com/forum/534098-post1.html I would probably bin them. Quote Link to comment Share on other sites More sharing options...
J D 8 Posted July 23, 2023 Share Posted July 23, 2023 (edited) Had similar with some Futaba's, it was the Y lead. Servos have gone on to give good service Edited July 23, 2023 by J D 8 more info Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted July 23, 2023 Share Posted July 23, 2023 I have seen this problem a couple of times, as above a weak signal from the rx, both times' arf's with installed servos from the Chinese, all on spectrum radios, they worked with a servo tester as they did with my Futaba receivers. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 23, 2023 Share Posted July 23, 2023 Swap out the Y lead 1st Quote Link to comment Share on other sites More sharing options...
Andy J Posted July 23, 2023 Author Share Posted July 23, 2023 Problem was indeed the Y lead which had a Futaba style plug mating with a JR style connector. Also the Y lead is 18swg wire so would prefer to get it out and replace it with a new longer 22 swg wire which will get rid of one short extension wire which I also found in each wing. Unfortunately its proving impossible to pull the Y lead through so will have to resort to cutting some of the sheeting at the centre dihedral break to gain access to the Y lead connections. Quote Link to comment Share on other sites More sharing options...
Andy J Posted July 23, 2023 Author Share Posted July 23, 2023 Well have done a bit more hacking and managed to get the old Y lead out and the new 22swg in up to each servo. Now uncertain if I solder up the new 22swg leads to make a new Y lead or take them directly to the Rx. Quote Link to comment Share on other sites More sharing options...
Outrunner Posted July 23, 2023 Share Posted July 23, 2023 Ditch the Y lead 1 1 Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted July 24, 2023 Share Posted July 24, 2023 (edited) Have come across this before - poor contacts in the plugs/ sockets. A thorough clean in contact cleaner might do the trick. Just seen that you've changed out the lead. Edited July 24, 2023 by Cuban8 Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted July 24, 2023 Share Posted July 24, 2023 You can also have this problem with Chinese uni/futaba mixing plugs and sockets 1 Quote Link to comment Share on other sites More sharing options...
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