Cliff Bastow Posted June 2 Share Posted June 2 I have an odd problem with my comet racer, it is set up how I always do twins, ie both esc signal wires into one channel one a y lead with the red wire disconnected on one esc. The throttles work fine but if I shut the throttles then use elevators or ailerons one motor will briefly run. The rudder does not seem to affect the throttle. If I go into the servo monitor function on my tx nothing shows on the throttle channel when using elevator or aileron! I have tried deleting the model completely then re setting it up to no avail. I am at a bit of a loss, any ideas anyone? thanks in advance. Cliff Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 2 Author Share Posted June 2 I should have said I fly Futaba and the tx is and 8 FG super with a genuine Futaba 8 channel rx. Quote Link to comment Share on other sites More sharing options...
Trevor Posted June 2 Share Posted June 2 Very strange. I’d try one ESC at a time - you’ll need a separate Rx battery for the one with the disconnected red wire. Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 2 Author Share Posted June 2 No one at the club could fathom it , even our resident Futaba expert! Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted June 2 Share Posted June 2 (edited) Which motor runs? the one with or without the disconnected red wire? Could be an induced signal pick up from the elevator/aileron servo wires.. Try disconnecting both red wires and running the rx off a battery or UBEC I know nothing about Futaba, but I don't think its a TX or RX issue.. unless that RX is faulty PS I have had ESC/RX power up issues where the second ESC gets confused as to the end points, but if I use a UBEC the RX and both ESC's are happy. Edited June 2 by Chris Walby 1 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted June 2 Share Posted June 2 That was exactly my thinking. Is it just the same motor or can it be either? If its always the same motor then its ESC is suspect. If it can be either motor then its ESC must be getting a signal. An ESC signal is exactly the same as for a servo so it seems that somehow the elevator or aileron signal is briefly getting to the ESCs. If you disconnect the Elevator and aileron servos from the Rx does it still happen? If it does it would suggest the fault is in the Tx or Rx not the wiring to the servos Having shown it is not the Tx or Rx If you disconnect the signal wires to each motor in turn. If they do not turn under the same test circumstances then it proves there must be a wayward signal getting to the motor's ESC. This would suggest there is some interference going on between the servo wires. This could require some careful inspection to ensure aileron servo wires and ESC wires are not running in close proximity. This sort of condition is more likely with wing mounted motors. Undertaking specific tests to logically eliminate each possible failure mode is about all you can do. 1 Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 2 Author Share Posted June 2 (edited) I was thinking of trying a different rx. I don’t think it can be the tx or something would be seen on the servo monitors surely? The aileron leads and the esc signal leads run together through grooves under the wings so could be some interference there I suppose but that doesn’t explain the elevator as the lead for that runs the opposite way along the fuselage to the esc wires along the fuselage as the servo is rear mounted. Edited June 2 by Cliff Bastow Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 2 Author Share Posted June 2 Doing some more investigation, the elevator causes the motor that’s esc still has the red wire to run and the ailerons cause both motors to run. I have to admit I am baffled! Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 2 Author Share Posted June 2 (edited) I don’t think it’s my tx as I have tried two other models with no issues. I suspect it might be the rx . If I unplug the elevator and aileron servos the problem goes away. Then I plugged a spare servo outside the model into the elevator channel and the problem returns. Edited June 2 by Cliff Bastow Spelling 1 Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted June 3 Share Posted June 3 Have you tried a different receiver? Quote Link to comment Share on other sites More sharing options...
RottenRow Posted June 3 Share Posted June 3 It also might be worth trying a separate receiver battery, and removing the red wires from both ESCs, in case the elevator / aileron servo operation is somehow disturbing the BEC output. Brian. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted June 3 Share Posted June 3 It sounds like cross coupling between servo wires if they are running together over a distance. It's worth trying ferrite rings at various places on the wiring, starting near the receiver. Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 3 Author Share Posted June 3 Thanks everyone for your help. I have tried a different receiver and it seems fine so I guess there is something wrong with the other one, some sort of internal feedback or something? The old one was a Futaba R617 FS so not a cheap one. Quote Link to comment Share on other sites More sharing options...
RottenRow Posted June 3 Share Posted June 3 As both of your ESCs were connected to the same receiver channel using a Y lead, I can’t see how even a faulty receiver could send a different signal to one of them compared to the other. Clearly your replacement receiver seems to have corrected the issue however. Brian. Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 3 Author Share Posted June 3 That’s true Brian does seem odd. Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 13 Author Share Posted June 13 (edited) I can confirm it is definitely the rx. Fitted a different one in this model and all ok. Fitted the suspect rx in a different model and bingo same problem, throttle briefly runs with aileron or elevator. Must be some sort of feedback or something? Strangely it’s fine with a servo plugged in throttle channel so might still be ok in an IC model. Edited June 13 by Cliff Bastow Punctuation 1 Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 25 Author Share Posted June 25 Bit of an update on this. It seems to be some sort of issue between the esc and the rx. The comet was fixed by fitting an orange rx. I tried the original Futaba rx in a different model which has the same make of esc, same problem so I thought must be rx. I then fitted another Futaba rx in the second model and low and behold same issue! Then fitted an frisky rx and problem went away. So it seems there is some issue using that make of esc with a Futaba rx. Any ideas anyone? Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 25 Author Share Posted June 25 The esc are 4 max supplied ones. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted June 25 Share Posted June 25 Quote Link to comment Share on other sites More sharing options...
Cliff Bastow Posted June 25 Author Share Posted June 25 Sorry Denis, I’m not sure of the significance of that? Quote Link to comment Share on other sites More sharing options...
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