My motor has started screaming

[Dave Hess]

I always take my Hobbyzone Carbon Cub S+ with me when i go flying, regardless of what other planes I take, and i normally give it a few flights. Last time, it worked perfectly as normal. This time I accidentally plugged in the battery before switching on the transmitter. When I did switch on the transmitter, the motor coughed a bit, then I initialised everything and went to fly it, but the motor was making a screaming sound.

Back home, I dismantled it from the plane and tried a different motor, which was fairly quiet, so I tried the original motor again, but not on the plane. it was a lot quieter, so I shrugged my shoulders and screwed it back on, but once tight, it was screaming again. I sprayed some oil into, which made a minimal difference. I'm not sure whether it's also running with reduced power, but I think it is. I'm kicking myself now for not trying it with another ESC while I could get to the connectors.

Everything looks pristine. I can't see or feel any fragments stuck to the magnets. The only thing I can think of is that somehow the ESC's timing has been altered. It's some sort of Hobbyzone ESC. I can't see more than that because it's fixed in a tunnel and I'd have to disassemble everything again to get at it.

Does anybody know if these ESCs are programmable or how to do it? Could it have inadvertently happened when I connected without the Tx powered? Any other ideas what could make it scream?

It also seems rough on start-up/tickover. I even saw it running backwards at tickover, like IC motors do sometimes.

[Biggles' Elder Brother - Moderator]

I wonder if you have accidentally gone into programming mode on the ESC? If you change timing etc strange things can happen! It might be worth considering doing a reset to default.

BEB

[Dwain Dibley.]

I second what BEB says....

However a good tip, and something I adhere to, is I always buy the same make ESC if I can..... and also purchase the programming card. Even if you buy an odd ESC, it still makes sense for a few extra quid to buy the card for it.

This makes trouble shooting and programming way easier........the alternative is listening to a million bleeps and twiddling tranny sticks.

D.D.

[Chris Bott - Moderator]

Dave also check that the prop or prop adapter isn't slipping.

I've had that make a screaming noise with the prop apparently running as normal.

[Chris Walby]

I had a motor very infrequently "kick back" on start up...found the problem after it dead sticked on me (the other was still running okay, who said only IC twins only do that!).

The problem.. manufacturers dry joint on a motor connector, real hard to find as the original heat shrink sleeve was very supportive. Re-soldered and all okay. Just a change of pants for the low altitude spin recovery.

[Dave Hess]

Well, I failed dismally to reprogram the ESC. I followed everything in the instruction, but it won't go into programming mode. I guess that the GPS initialisation routine is interfering with it. It makes the tail wiggle after you plug in the battery. The programming procedure is to plug in while you have full throttle, which is what i did, but I didn't get the beeps to tell me that it's gone into programming mode. Anybody any ideas?

I took the prop and adapter off and I even tried another prop. I want to keep an open mind, but it does look and sound like the timing's out.

[GrahamC]

Screeching and kicking on startup is often a sign of a failing solder joint on one of the connectors between the motor and the ESC as Chris says. Worth checking.

[Nigel R]

I had a similar 'sudden whine' type problem - turned out the shaft itself had come slightly loose within the motor. Result - naff all power, lots and lots of noise.

[kc]

Recently after 1384 flights ( = about 138 hours) my Turnigy 3536 made odd noises. Investigation found that one of the bullet connectors had partially unsoldered due to a slightly loose fit in the socket and subsequent overheating of the bullet which caused the solder to melt and run out. Intermittent connection caused the ESC to protest noisily . Re-soldering and crimping the socket a little cured the problem. Now up to 1419 flights all in the same model.

Edited By kc on 26/09/2018 17:00:05

[Dave Hess]

Thanks for your suggestions. i'll have to look deeper into it.

I did take the motor off and check it, but everything looked and felt OK. I tried a different motor, which seemed quieter, but It's difficult to tell because the faulty one was fairly quiet too with the prop removed. I put it all back together and i convinced myself that it was a bit quieter and the lack of power was just my imagination, so I took it down the flying field to try it; however, it was nothing like before. It was a bit like an under-powered trainer and took most of the square to get airbourne It was no fun to fly it like that.

[Outrunner]

Posted by GrahamC on 26/09/2018 14:41:04:

Screeching and kicking on startup is often a sign of a failing solder joint on one of the connectors between the motor and the ESC as Chris says. Worth checking.

I've had exactly the same, intermittent screach noises and prop rocking backwards and forwards, dodgey connection between esc and motor.

Phil.

[Dave Hess]

I had another look today and did some more tests. One thing I noticed is that the motor didn't actually start until the throttle was some way up, then it jumped in with reasonable speed on. I tried a different ESC, which solved all the problems. With the new ESC, the motor was rotating slowly at zero throttle and picked up speed normally.

I pulled the heat-shrink off the faulty ESC and couldn't see anything wrong. All the solder joints looked good.

Using a different transmitter and receiver, I was able to get into the programming sequence, which isn't possible using the OEM receiver. I guess that the stabilization and or navigation routines interrupt the receiver so that it can't cooperate with the ESC's programming. I tried different timing, but all gave the same dentist drill sound and jumpy starting.

My conclusion is therefore that one of the mosfets must be faulty, so unless anyone can say otherwise, it's going to be marked with a U/S sticker.

One thing I don't understand. The motor is a Parkzone PKZ4416 960kV, which is relatively large compared with my other motors. The ESC is a Parkzone PKZ1814 18A, which seems very low for such a motor, though it's bigger than the EMax BLHeli 30A ESC that I replaced it with.

[Peter Beeney]

I think I might well be tempted to have at least one more look at the 3 motor connections on that ESC if it were me Dave. Sometimes the soldering on these things does leave a bit to be desired. I had a completely dry soldered connection on an ESC which lasted ok through the first owner and then for many flights for me until after a landing in the long grass the motor suddenly refused to run any more. When I eventually found the little gremlin I actually pulled the wire out of it’s socket cold. There is a photo here in my Hextronic Battery Monitor album, next to bottom row on the right.

One simple experiment you might be able to try goes like this. With the heat shrink removed from the connections you should be able to latch a croc clip onto the sleeve and the wire where they join. Press it firmly together so that the teeth bite well into both at the same time; then each motor wire in turn. I reckon this at least will be good enough to prove if there is a dodgy connection or not.

I know it’s not a given certainty, but I think that on the very rare occasion that I’ve seen any ESC power transistors blow they tend to resemble the leftover remains of last night’s burnt barbecue…

You are right about the motor details being confusing too. So far I’ve not really looked that hard but there does seem to be a distinct lack of detail available. I’d have thought that a 480 brushless would be in the 20 -25 amp bracket so an 18A ESC might be a bit on the economical side… Having said that it does seem to be the supplied unit. As it happened I had a foamie that spent all it’s flying time with it’s supplied ESC overloaded too but it never ever blinked… But it did have it’s own bespoke wind tunnel cooling system which it slotted into as part of the design; and I think this was the reason it never became overheated… it definitely wasn’t through lack of trying…

Good luck.

PB

[Dave Hess]

Thanks, Peter. I pulled the heat-shrink off the connectors to check the soldering. It's perfect. I've also done a rudimentary check of the MOSFETs. I get 54K between all three phase wires and both the positive and negative battery wires, so the mystery deepens.