Witterings Posted February 3 Share Posted February 3 I was checking the control surface movements on a model and noticed one aileron servo was much slower to respond than the other. Initially I thought maybe something was binding but on further investigation and disconnectin the pushrods realise it's the servo itself. I've ordered another anyway but what would most people do with it, it's a Hitec HS 65 MG and you can buy spare gears for them so am wondering whether to do that and keep a spare, it's 2/3 rds of the cost of a new on though. Just gererally is this typical behaviour of a servo starting to fail, I wonder if maybe some glue managed to get into it when building / fixing it to the plane but it was hot glue so not runny like thin CA so would have thought it unlikely. Just interested to hear people's general comments on what it may be and whether to try and repair with a new set of gears or not bother. Quote Link to comment Share on other sites More sharing options...
Simon Lumsdon 1 Posted February 3 Share Posted February 3 Check the wiring, has the connection loosened or dirty/oily Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 3 Share Posted February 3 Save it for the gears etc, fit new one. 4 Quote Link to comment Share on other sites More sharing options...
Brian Cooper Posted February 4 Share Posted February 4 Yes, it is typical behaviour for a servo failing. It will probably be slightly faster in one direction than the other, or it might feel freer in o e direction. The servo will feel hot in the area of its motor. Replace it, and keep the old one for spare gears. . Tie a knot in the lead so it can be identified as the faulty one. 1 Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted February 4 Share Posted February 4 I was checking my Futura helicopter Sunday ( 20+ years old) and found that one of the Futaba S9202 servos on the swashplate had a small amount of play, I stripped it only to find an enormous amount of wear on one of the small gears and a tooth missing on it, needless to say I replaced all three of them, another lucky escape ! 1 Quote Link to comment Share on other sites More sharing options...
Don Fry Posted February 4 Share Posted February 4 14 minutes ago, Paul De Tourtoulon said: I was checking my Futura helicopter Sunday ( 20+ years old) and found that one of the Futaba S9202 servos on the swashplate had a small amount of play, I stripped it only to find an enormous amount of wear on one of the small gears and a tooth missing on it, needless to say I replaced all three of them, another lucky escape ! Not luck, good procedure. Simples. 2 Quote Link to comment Share on other sites More sharing options...
Witterings Posted February 4 Author Share Posted February 4 9 hours ago, Brian Cooper said: Yes, it is typical behaviour for a servo failing. It will probably be slightly faster in one direction than the other, or it might feel freer in o e direction. The servo will feel hot in the area of its motor. Replace it, and keep the old one for spare gears. . Tie a knot in the lead so it can be identified as the faulty one. Yes, you're right, it was faster in one direction than the other. Because I've never had anything similar happen before despite thousands of flights (apart from a complete failure mid flight), I've never thought about a servo's components but I guess they must have a motor inside and unless the gears did get some glue or something in them, then it's probably the motor itself which is failing? Hopefully the new one should be here today and will fit that but may take the old one apart later anyway as I've never done it before. 1 Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted February 4 Share Posted February 4 Servos are amazingly reliable and as a bonus will very often give warning signals that all is not well before a catastrophic failure. So important to check gear over and of course a preflight check every time. Witterings......have a go at dismantling the servo to see what's going on - it's not difficult but just fiddly. You've nothing to lose really. Take photos so you know how it all fits back together. Yes, the gear sets are a silly price for that servo but it'll be a good excercise to get it up and running again if indeed the gear train is at fault. 1 Quote Link to comment Share on other sites More sharing options...
Ernie Posted February 4 Share Posted February 4 Dont take any chances with critical components. Replace it. Then, carefully take it to bits. Photo the inside at each stage so you can see how it goes back together. You'll learn a lot, and maybe the problem will be so clear that you'll be able to fix it ernie 3 Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted February 4 Share Posted February 4 One thing that might catch you out as you've not stripped a servo before is getting it to centre correctly after reassembly. You're bound to move the feedback pot from its factory set position so you'll need a servo tester set to 'centre' so that you can tweak the servo pot to the correct position if need be as you fit the gears back. Might have to take the gears of a couple of times to get it right or as close as you can. Sounds complicated, but you'll see what's happening and figure it out. 1 Quote Link to comment Share on other sites More sharing options...
Witterings Posted February 4 Author Share Posted February 4 32 minutes ago, Cuban8 said: and of course a preflight check every time. I used to do this religiously but several years of not flying and I've got out of the habit which I need to get back into .... My TX, whilst I hadn't used it for ages seems to have a problem remembering settings and direction of control surfaces at the moment on some models which is a bit scary but even more reason for doing this. Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted February 4 Share Posted February 4 (edited) 24 minutes ago, Cuban8 said: One thing that might catch you out as you've not stripped a servo before is getting it to centre correctly after reassembly. In the past, and maybe on cheap servos, but not on any Futaba ones for the last 25 years,,, Edited February 4 by Paul De Tourtoulon Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted February 4 Share Posted February 4 23 minutes ago, Witterings said: My TX, whilst I hadn't used it for ages seems to have a problem remembering settings and direction of control surfaces at the moment on some models which is a bit scary but even more reason for doing this. I'd suggest that's a 'stop using' immediately fault.... Quote Link to comment Share on other sites More sharing options...
Witterings Posted February 4 Author Share Posted February 4 3 minutes ago, GrumpyGnome said: I'd suggest that's a 'stop using' immediately fault.... Certainly I'm in a monitor very closely situation at the moment but it's only 1 model so far but will keep a very careful eye on it and also see if it does it with any of the others ... I may copy the "problem one" to another position, leave it a few days and see if it does it again. Some devices, even a computer has a small battery that remembers things like date / time and gives something like a TX just enough power to remember settings, is there one inside a TX do you know. Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted February 4 Share Posted February 4 (edited) 46 minutes ago, Paul De Tourtoulon said: In the past, and maybe on cheap servos, but not on any Futaba ones for the last 25 years,,, Refering to the setting of the feed back pot during reassembly, not so much to the centering quality of the servo as a whole. Agree, even many inexpensive servos today have a quality approaching or even equal to what was available several decades ago, and which we paid quite a bit for at the time. The old Futaba 128 and its predecessor types were around ten to fifteen pounds back in the 80's and 90's which according to Google is the equavalent to £50 - £60 today. Your transmitter issue sounds potentially very serious if it's losing it's programmed settings - really needs investigating and I'd urge you to not use the tranny if you are in any doubt about it. Annoying, but you'd not have a leg to stand on in defence should a serious accident be caused by a suspected or known fault with the gear was found to be to blame. We live in a totally different world today which is nothing like the free and easy, 'suck it and see' way of things back in the day. Edited February 4 by Cuban8 Quote Link to comment Share on other sites More sharing options...
Learner Posted February 4 Share Posted February 4 40 minutes ago, Witterings said: Some devices, even a computer has a small battery that remembers things like date / time and gives something like a TX just enough power to remember settings, is there one inside a TX do you know. Yes some transmitters have an internal battery, my old JRs for instance. 1 Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted February 4 Share Posted February 4 I suspect most computer radios have an rtc (Real Time Clock) battery - certainly my Radiomaster does as it 'remembers' the tine etc. if I remove the main battery.... Quote Link to comment Share on other sites More sharing options...
Konrad Posted February 4 Share Posted February 4 (edited) This slow in one direction is a clue that one of the transistors in the output stage of the servo amp is failing. Check that there isn't a bind on one side of the surface motion that might have stressed one side of the amp over the other. Edited February 4 by Konrad Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted February 4 Share Posted February 4 8 hours ago, Witterings said: I used to do this religiously but several years of not flying and I've got out of the habit which I need to get back into .... My TX, whilst I hadn't used it for ages seems to have a problem remembering settings and direction of control surfaces at the moment on some models which is a bit scary but even more reason for doing this. If its a JR Tx then the internal battery will need replacing . This keeps memory alive. Quote Link to comment Share on other sites More sharing options...
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