Steve Hargreaves - Moderator Posted May 15, 2013 Share Posted May 15, 2013 Don't forget to re-fit the prop before you try & fly it..... Good luck.... Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 15, 2013 Author Share Posted May 15, 2013 Posted by Steve Hargreaves - Moderator on 15/05/2013 13:46:33: Don't forget to re-fit the prop before you try & fly it..... Good luck.... lol! My cluelessness has been epic, but thank god for internet or I might be in A&E right now with a chopped finger, and/or a smoking ruin of a plane. thanks again. Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 16, 2013 Author Share Posted May 16, 2013 hey guys, seems I'm not ready to get off the ground just yet. Got all my servos nicely aligned and trimmed, but I'm having a problem with servo judder especially the rudder. It is still when I start and as soon as I start moving it, about 50% of the time it starts juddering. Centering it, the judder continues and the only way to make it stop is to do a quick full stick to right/left and then it normally stops. I tried changing it for a spare but had the same problem. The other servos also sometimes do it but not as much as the rudder. Any ideas? Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 16, 2013 Author Share Posted May 16, 2013 btw my servos are 'Towerpro 9g SG92R with Carbon Fibre Gears'. Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 16, 2013 Author Share Posted May 16, 2013 I might be jumping to conclusions, but it seems to me the servos are just rubbish. Of the 5 I bought, only 1 is stable when holding the stick partially over, the rest jitter to a greater or lesser degree. Could anyone please recommend another 8-9g 1.5kg+ torgue servo they have found reliable without breaking the bank? Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 16, 2013 Share Posted May 16, 2013 Hi Brent, I'm sure a few of us have been having a think about this during the day. I think the likelihood of all the servos being duff is pretty low, so clutching at straws, I wonder if your Rx pack voltage may be a little low, or possibly even if whilst setting up, the Tx is quite close to the Rx? Fellow mod, Chris Bott, also thinks it's worth looking at your Tx monitor screen (if you have one) to see if there is movement in the bugs which could indicate a radio, rather than servo, issue. Let's see if we can establish what the problem isn't before you commit to more servos Pete Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 16, 2013 Share Posted May 16, 2013 If you do end up looking for other servos, I've been quite happy with the Emax ES08MA when I've needed a metal-geared 9g servo. Others in the budget line that (most of the time!) seem to work OK are the Emax ES08A, Towerpro SG90 or Hextronik HXT900 (probably both the same servo re-badged) but they are plastic-geared. Quite frankly, with 9g servos, I've found they either work fine from the start and carry on working well, or they play up straight away or very soon after...... The alternative is to look more up-market in the Hitec or Futaba range, perhaps? TBH, I always think it's fraught with peril suggesting items like this - we all have different ideas.opinions and experiences.... Pete Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted May 16, 2013 Share Posted May 16, 2013 I’ve just caught up with this thread and suspect it might be the other way round, Pete, the UBEC’s output has possibly defaulted to 6 volts, and the servos might be 4.8 volts. This will definitely cause servos to jitter, and worse! I think at least Brent needs to check the output and make sure it’s no higher than 5 volts, it’s probably adjustable, and if they still insist on playing up then it might be a case of new servos; but as you say, at the moment it’s a big coincidence… Hope this is of some use.. PB Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 16, 2013 Author Share Posted May 16, 2013 Hi Pete, I tried what you suggested but no luck, although I couldn't find a monitor screen on my Tx - don't think I have that option on Futaba T7c. Thinking perhaps there's some sort of interference, I took the ferrite ring off the UBEC (this one:**LINK**) and put it on the worst servo, but there was no difference at all. Could it be worth trying to up the voltage from the UBEC by using the jumper? Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 16, 2013 Author Share Posted May 16, 2013 Hi peter, just saw your post after I posted mine, will check the output voltage and report back Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 16, 2013 Author Share Posted May 16, 2013 ok, well the UBEC was definitely set to 5V. It is adjustable to 6V and because my servos operating range said 4-6V I thought it safe to test it on 6V. Well the jitter was twice as bad on 6V, not able to get them still at all. Makes me think perhaps we're on to something and even the 5V is just too much for the servos? Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted May 16, 2013 Share Posted May 16, 2013 Brent - it’s unlikely that 5 volts will be too high, a 4 cell pack has a voltage of around 5.3 volts. 4.8 is the half way mark, between 5.3 down to 4 volts. Do you have a 4 cell receiver pack you can try? If so, remove the throttle cable and plug it in, - that will prove the UBEC one way or the other. PB Sorry, should have said remove UBEC supply, I’m not yet used to all this electrical stuff! Edited By Peter Beeney on 16/05/2013 23:02:18 Edited By Peter Beeney on 16/05/2013 23:03:08 Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 16, 2013 Author Share Posted May 16, 2013 No Peter, unfortunately no receiver pack. I agree there does seem to be too much coincidence for the problem to be the servos, but on the other hand, it's weird that the elevator one is almost perfect. I guess another thing pointing to the problem not being the servos, is that when the ailerons start jittering, they do so together, and they stop together, so would this then point to some sort of inteference, or maybe a faulty UBEC? Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 17, 2013 Author Share Posted May 17, 2013 Guys I think it's become clear my best course of action is to go into a shop where hopefully they can test all the different things the problem might be. thanks for all the help thus far. Quote Link to comment Share on other sites More sharing options...
John Privett Posted May 17, 2013 Share Posted May 17, 2013 Posted by Brent Mills on 16/05/2013 23:04:38: I agree there does seem to be too much coincidence for the problem to be the servos, but on the other hand, it's weird that the elevator one is almost perfect. I'd try disconnecting all the servos except the elevator servo, then see how it behaves when you plug it in to each of the other channels in turn. Then try each of the other servos in turn plugged in to the elevator channel with no other servos connected. That may narrow down whether it's the servos that are faulty or interference being picked up and passed to the servos. I have heard of cases where a faulty servo can cause other servos plugged in to a different channel to jitter... Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 17, 2013 Share Posted May 17, 2013 Brent are you using 35MHz here? I've had UBECs that just wouldn't work with 35MHz no matter what I did....filters, PCM Rx.....the servos just jittered & did all sorts of things. That said I've had UBECs that work fine with 35MHz.....its all a bit of a lottery. Trying a 4 cell Rx battery would be worth it.....these provide a nice clean 5 volts DC without any of the harmonics & "noise" you can get from a UBEC The only other thing I could think of was a dodgy connection somewhere.....I've had odd servo behavious which turned out to be a faulty negative wire on an extension lead.....unlikely to cause a problem on ALL servos though..... Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 17, 2013 Author Share Posted May 17, 2013 Steve, no it's 2.4ghz, I have a Futaba T7c. John I tried your suggestion and the elevator servo works almost perfectly in all receiver slots. When I plug the 'dodgy' servos into any slot on their own, they still jitters. So it's looking more and more like I got unlucky with 4 out of 5 bad servos. Going to the shop this afternoon for some testing with other servos and will let you guys know how I get on. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 17, 2013 Share Posted May 17, 2013 Ah OK.....2.4GHz is usually OK & pretty immune to most "noise".....it does start to sound like the servos.... Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 17, 2013 Author Share Posted May 17, 2013 All sorted! (although it cost me a bit) Turns out there was a problem with the servos AND the receiver! Hows that for rotten luck? At the shop we plugged in a new servo into the rudder slot and it buzzed away. We replaced the receiver with a Futaba one and my towerpro servos were still jittering, but when we got the new servos on the new receiver all worked perfectly. Leaving the so called 'perfect' elevator servo in with the new 'New Power' servo on the rudder, the difference in smoothness is really huge making the towerpros look like total junk even at their best. So bad feedback is going onto the receiver and servos I bought so others can avoid this expensive headache. For clarity the dodgy items were: -Frsky FASST-compatible TFR8-S Receiver -Towerpro 9g SG92R Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 18, 2013 Author Share Posted May 18, 2013 hey guys, I'm happy to report that the maiden flight went absolutely fantastic! Managed some knife edges and brief hovers (at altitude of course). It's quite remarkable how good a simulator is at preparing you for the real thing, because the handling felt almost exactly the same. Thanks everyone for helping me get airborne! Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 18, 2013 Share Posted May 18, 2013 That's great news, Brent - thanks for letting us know! Pete Quote Link to comment Share on other sites More sharing options...
John Privett Posted May 18, 2013 Share Posted May 18, 2013 Brent, as you mention "bad feedback" I'd guess the rx and servos were ebay purchases? If that is the case, there are a lot of counterfeit servos around there. A lot are "Futaba" ones, but also Towerpro seem to get faked a lot according to various reports. As for the Frsky FASST compatible rx, that does seem unusual, many of us on here use them and I rarely hear of any issues with them. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 18, 2013 Share Posted May 18, 2013 +1 for the FrSky FASST Rxs.....I have quite a few & they've been faultless..... Quote Link to comment Share on other sites More sharing options...
Brent Mills Posted May 19, 2013 Author Share Posted May 19, 2013 No they were bought on Giantshark. The Rx problem was strange, we put new servos into it and it 'buzzed' worse than the towerpro ones. Plug the new servo into a futaba receiver and it's dead quiet and perfectly smooth. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 19, 2013 Share Posted May 19, 2013 Which Rx is it Brent? Is it the TFR8? If so this Rx has a high & low speed latency setting....the high speed only suits digital servos & will make analogue servos buzz like anything..... You can change the latency from high to low speed...check the instruction sheet that came with it... Quote Link to comment Share on other sites More sharing options...
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