An answer to your question about any damaged or burnt wiring. The black lead from the speed controller to the RX was completely burnt through, however the receiver has worked fine since i replaced the speed controller.

Hi Andy,
Sounds like you may have had something else connected to the RX which put a short (or a heavy impulse load) across the BEC supply line! Was there any other obvious damage to any wiring? Doug

Hello. It’s strange, no one I’ve asked have an answer, Mtronics didn’t have an immediate answer when I phoned and asked for it to be returned, see what they say.

I had the same problem with a V40 Speed Controller. Used several times, until i switched on the the power through the RX and a proper smoke out. Controller was completely burnt out through the power switch. Still cannot understand Why?. A new Speed Controller was purchased, no problems since.

Thank you once again. I’ll keep you posted re the speed controller
Regards Brian

Hi Brian,
The Mtronics guys seem a reasonable bunch so I hope they'll send you a replacement 🤞
Re: fuse, my measurements on the Sea Scout with the same rating motor you have and 3S LiPo never showed more than about 8Amps current at full chat so I have fitted a red 10A car blade fuse.
Clearly visible in the pics I've posted. My ESC is also rated 30A. But I wouldn't fit more than a 15A fuse at most with that motor. Some might go to 20A but while protecting the ESC Ok that may risk damage to the motor or wiring before it blows.
Was glad to see that the RX had survived OK 😉
Good luck with Mtronics👍 Cheers, Doug 😎

Hello Doug. I spoke with Mtronics today and they know of no reason why this should have happened. The helpful man asked me to return the speed controller for them to investigate. I will keep you informed.
Regarding fuse in the battery feed I’m unable to identify the stall current of the motor. Current rating for speed controller is 30 amps, what fuse would you suggest?
Thank again
Cheers Brian

Hello again
I will. It’s strange I havent had the problem before either. Yes I have tested the receiver on the rudder servo and all is well there fortunately
Regards Brian

Bon chance mon ami!
Would be good to know what went wrong, to help others avoid the problem👍
I also have several Mtronics ESCs; Viper Marine versions.
Not had any problems ..... YET 😉
Cheers, Doug
PS A quick thought! Have you tested the RX with just a servo connected after the disaster?
You'll need a separate RX battery (4.8 to 6V) to do this of course.

Hello Doug. Thank you again, i appreciate your help, i’ll phone Mtronics on Monday and see what they suggest before I wreck a second speed controller. The good news is the smell has very nearly left the room!.
Thanks again, if I get an answer I’ll let you know
Cheers Brian

Hi Brianaro,
First mistake 🤔
Rule is ALWAYS switch on the TX FIRST! ALWAYS switch off the RX first.
This prevents the servos and/or ESC going mad because they are not getting a stable control signal with the TX off.
It doesn't matter which way you connect the 3 wires to the motor; as long as you don't mix up the red motor wire with the red battery wire! 💥 But since you say the motor ran that can't be the problem. A mix up is highly unlikely anyway.

Why switching on the TX apparently caused the 'magic smoke' is puzzling🤔 UNLESS maybe the throttle stick was set to full chat and the motor overreved and the inrush (or start up) current overloaded the ESC. But I thought that the Hydra is internally protected against this.

Can only suggest that you call Mtronics, or first go back to the shop with the sad remains!!
Your setup is virtually identical with my Sea Scout setup, just different makes but same values.
I use the car blade type fuses, see attached pic of Sea Scout's 'engine room.
I solder the fuse holder to a little Veroboard switchboard, but you can also get in-line versions.
Sorry I can't pinpoint the problem further😌
Good luck🤞
Doug

Hello Doug, thank you. I have the Mtronics G2 Hydra 50 system brushless motor and speed controller, Overlander 35c LiPo 11.1v 3900mAh battery and a Tamia TX and RX, all was provided together from Howes Models.
I have successfully connected it all together and run it on several occasions for test purposes without a problem.
The battery connects with a Tamia connector which can’t be reversed and the motor has three colours cables, red, yellow, blue as does the speed controller.
I switched in the RX before the TX and the motor ran as it has previously, I quickly switched on the TX and whoosh! Lots of smoke from the speed controller.
I am sure I connected the mayor/speed controller cables correctly however when it all went wrong I very quickly disconnected the battery and the motor leads so didn’t see how they were connected. One of the pins in the Tamia connector to the battery disappeared as well, not sure if it melted or broke off when I pulled it apart.
If I had connected the motor cables incorrectly would that have caused this.
Also, what type of fuse do you suggest? Eg car type
Thanks again

Hi Brianaro,
Agree with above advice re fusing, standard practice!
Fuse rating should be significantly less than the stall current of the motor and / or the maximum current rating of the ESC.
Fit fuse between battery and ESC.
With brushless (3 wire) motors you could fit fuses in each lead between ESC and motor but not normally necessary with Mtronic ESCs. They have built in motor short protection anyway.
To help you further we need to know the following-
- Make and model of the receiver, the Hydra manual contains warnings about the pin connections of older receivers!!
- Make and model of the motor,
- Are you using the BEC from the speed controller for the RX or a separate RX battery pack,
- If so did you disconnect the red wire between ESC and RX,
- Are you sure you connected the power capacitor the right way round?
Cheers, Doug 😎
PS: If all else fails- "Need Help? Call our specialists on 01943 461482" Ask the 'Moronic guys 😁

Hello, thank you for that. The battery connectors only fit one way red to red black to black and the Mtronics Hydra 50 was supplied direct from Mtronics with the brushless motor, thank you for the fuse suggestion I like that idea. Are you suggesting between the battery and speed controller or speed controller and motor, or both?

Have you got the + and - wires the right way round on the battery or is the motor to powerful for the speed controller
I put a fuse in the positive wire and it has saved several controller when connecting the wires the wrong way round on the battery hope this is of some help