Second Motor turns really slow after crash - RC Groups
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Sep 24, 2012, 09:01 PM
Registered User

Second Motor turns really slow after crash

Hey guys,

I'm new to the hobby and just got a Dynam PBY Catalina. On my first flying attempt the plane took off, immediately rolled to the right and fell top first into the water from about 2m or 3m height. Now that everything has dried and I was trying to asses the damage, it turns out that one of the motors won't really turn anymore. If I push the throttle all the way forward, the right motor runs at full speed, but the left runs so slow i can see the screw turning. (It's not really smooth, more like turn - turn - turn - turn, like something would block the motor).

Any ideas? Throttle control broken? The receiver seems to be fine, I packed it into a plastic back, so it didn't get any water in it. The wiring doesn't seem to be faulty either, the motor gets the signal, just doesn't turn.

I hope I can get it fixed without having to purchase new parts.

Thanks a lot.
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Sep 25, 2012, 03:29 AM
Registered User
Eclipse_7's Avatar
Does the motor stop and start, or just pulsate? If its a rough start and stop motion you may be missing a phase on your motor.

You can do a bit more testing since it is a twin. Plug the suspect motor into the working ESC and test it. Then plug your working motor into your suspect ESC. That should isolate where the fault is.
Old Sep 25, 2012, 06:01 AM
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Sep 25, 2012, 06:08 AM
Registered User
Thank's Eclipse_7,
It's a pulsating start-stop motion.

I connected the motor to the other side and it works flawlessly with the other ESC.

When I start up the motors and turn the broken one by hand it turns over and runs normally, I can than just regulate thrust without problems. If I cut the power and restart it works as well most of the times, but sometimes it pulsates again.
Sometimes it works if I start with full throttle instead of increasing it slowly.

I checked all the connections on the ESC and the motor and couldn't find lose connections. Everything checks out fine.

The broken one get's way hotter than the working one, even if the motor turns over and runs normal. I hope there is a way to fix it, new ones seem to be quite pricey.
Sep 25, 2012, 07:16 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Originally Posted by mrgoodkat
I connected the motor to the other side and it works flawlessly with the other ESC.
Then there is your answer. If the suspect motor runs fine when you connect a different ESC then it must be the original ESC that's causing the problem. It's worth double checking that the solder joints on the three wires between ESC and motor are good and that the connectors are all making a nice tight connection. Also try the suspect ESC on the motor that runs ok.. if that motor then shows the problem then you can be 100% sure it's a bad ESC that's to blame.

ESC's are pretty cheap.


PS.. if you have not flown RC before you have the wrong model to learn on and you are almost sure to just keep on crashing. Get a trainer and find and experienced flyer to help you.

PPS.. if the motor doesnt spin when you power it up close the throttle immediatly. Trying to force a motor to start will very likely result in burning out the coils of the motor.. that's why it feels so hot.

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