andy oliver 1 Posted November 13, 2016 Share Posted November 13, 2016 I had a low speed prop strike in long grass with an Eflite Timber. The prop and motor appeared to have sustained no damage whatsoever and their shafts are still perfectly unbent. However when power is applied to the motor the propeller initially oscillates back and forth a few degrees, and then accelerates normally as more power applied while making a high pitched buzzing noise. At full throttle it will not produce much more than about half power. As the motor itself appears fine is it possible the ESC has failed or it's programming has somehow gone haywire ? Motor EFLM 108018 ESC EFLA 1040U Many thanks Quote Link to comment Share on other sites More sharing options...
Keith Berriman Posted November 13, 2016 Share Posted November 13, 2016 Andy Try a start up procedure with TX and ESC you may get away with it Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted November 13, 2016 Share Posted November 13, 2016 Possible Andy but I wonder if you have a loose or poor connection between ESC & motor......the impact may have made it bad enough to have this effect. Cleaning the enamel off the copper motor wires is not easy & often the result is a poorly soldered connection...even straight from the factory. I'd have a little look in this area first....try gently twisting/pulling the wires from the connectors & see what happens... Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted November 13, 2016 Share Posted November 13, 2016 Initial thought is that it is still the motor even if it looks OK. When you rotate the motor by hand is there any resistance? Has one or more of the magnets come adrift. Is it easy to strip the motor down? If it were me I would try the motor with another ESC or try your ESC with another motor to try to eliminate the problem. Connect up a watt meter, run the motor and see what amps and volts you are getting. Good luck. Just my 2p worth. Quote Link to comment Share on other sites More sharing options...
MattyB Posted November 13, 2016 Share Posted November 13, 2016 Have to agree, given the symptoms and the fact they were preceded by a prop strike means it is far more likely to be a motor or connection issue than an ESC issue. Check all your external ESC to motor connections first and test with a spare ESC, but if you find nothing there you are going to need to disassemble the motor to find the cause. Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted November 13, 2016 Share Posted November 13, 2016 I think it may be the ESC, they don't like stalled motor shafts even at low speed settings. I had a field landing/crash and didn't go to throttle off as it stopped against the ground (prop strike) and the only damage was a u/s ESC! If you have a meter, measure between the motor leads (the resistance should be very close to each other). If you don't have a meter, then either substitute a spare motor or ESC in place and try it (remember not to run the motor for more than a couple of seconds off load) Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted November 13, 2016 Share Posted November 13, 2016 andy oliver 1 By far the best (and quiickest) way to check is by 'substitution'. Connect up another motor (no prop) to the suspect ESC. If it spins up ok then it is the old motor. If it still does the same thing then it must be the ESC (or the connections). I always have a spare ESC and motor permanently "on the bench" with basic terminal block connections to identify just this sort of problem. Quote Link to comment Share on other sites More sharing options...
andy oliver 1 Posted November 15, 2016 Author Share Posted November 15, 2016 Many thanks for all the above. I will try all the suggestions and post the result Quote Link to comment Share on other sites More sharing options...
andy oliver 1 Posted November 21, 2016 Author Share Posted November 21, 2016 Thanks again for suggestions. It turns out Chris Walby was right and the ESC had failed, I guess I hadn't closed the throttle quickly enough after the prop strike - every day's a schoolday ! Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted November 21, 2016 Share Posted November 21, 2016 I had the same or very similar symptoms with one of my models. I tried changing the ECU all seemed fine for a couple of flights then symptoms started again . I finally found the culprit was one dodgy connector to the motor . Replaced that and has been fine now for a couple of years. Quote Link to comment Share on other sites More sharing options...
Geoff S Posted November 21, 2016 Share Posted November 21, 2016 Posted by Engine Doctor on 21/11/2016 15:06:25: I had the same or very similar symptoms with one of my models. I tried changing the ECU all seemed fine for a couple of flights then symptoms started again . I finally found the culprit was one dodgy connector to the motor . Replaced that and has been fine now for a couple of years. As a teenager, I worked in the service department of a TV/radio manufacturer (Murphy Radio, if anyone remembers them) and it was normal practice to go back a stage once a fault had been found to see if it returned. We used to get radios back that dealers had given up on and they were most often intermittents. It looks like that's what yours was ED. Most electrical faults can be down to poor connections somewhere, most often connectors or, less often, dry joints. Geoff Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted November 21, 2016 Share Posted November 21, 2016 Prop vibrating back and forth is a classic indication of a poor / missing connection on one of the three wires between ESC and motor - unplug each one check both the male and female connectors for mechanical integrity then plug back fully, do one at a time so your dont reverse rotation direction Quote Link to comment Share on other sites More sharing options...
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