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Author Topic: '....the motors go into full reverse……but why?'  (Read 937 times)

ChrisH1981

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'....the motors go into full reverse……but why?'
« on: May 27, 2022, 09:54:20 am »

Morning all, it seems the only time I post on these forums is when I have issues! Sorry!
Anyway, Ive just come back home from a little sail at the lake where something very dramatic happened.
I was sailing my new to me (second hand model brede lifeboat, 1;12th scale)

Previous owner has fitted 2 x electronize speed controllers 30 HV ones, and a planet TX RX receiver is the radio setup.
Anyway, gently sailing around nice and relaxed until suddenly the boat kicked into FULL REVERSE! Ive now got the boat diving stern first into the water!!!! And im out of control with water washing over the stern deck! ( a good minute or two passes with me desperately trying to regain control all the time knowing water must be pouring into the hull)
Luckily somehow it came to a stop after this terrifying moment.
Now im pretty sure ive gathered why this happened….the signal between the TX and RX was lost….ive proven this because on the bench….when I turn off  the TX, the motors go into full reverse……but why?
I assumed if signal is lost it should go into a failsafe mode right?

Im nervous about using the model now until I understand or put measures in place to stop this happening again.
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C-3PO

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Re: Heart stopping moment!
« Reply #1 on: May 27, 2022, 10:30:48 am »

It sounds like the RX did revert to fail safe mode...

The position of the throttle "failsafe" may not be what you want or intended i.e. full stick down = full reverse, this would be the default setting of the failsafe for an RC Aircraft where full stick down is low throttle setting (likely to be the setting as the radio set was manufactured)

What radio set (Make/model) do you have?

Often the failsafe is set by the position of the RC control "stick or switch" to the required "failsafe" position with RX powered on - TX powered off, then TX power on - but sequence/process does vary depending on the radio set.

Regards
C-3PO
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NickelBelter

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Re: Heart stopping moment!
« Reply #2 on: May 27, 2022, 10:32:38 am »

Yes, that is undoubtedly the failsafe for gas motors, dropping the throttle to zero (which means full reverse in a bi-directional stick setup).  Simplest fix is to use a different channel for the throttle, moving the ratchet mechanism over if you want. 

The more involved solution is determining why the model lost signal in the first place.  That would involve checking the Tx and Rx power supplies for issues. 
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ChrisH1981

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Re: Heart stopping moment!
« Reply #3 on: May 27, 2022, 10:36:28 am »

Im using a planet T7 TX and RX....throttle is setup on LH stick using spring centering
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ChrisH1981

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Re: Heart stopping moment!
« Reply #4 on: May 27, 2022, 10:42:15 am »

For further information, the speed controllers are

Electronize FR30HX

I dont know much about these, they are discontinued? Does anyone have any litrature on them, for example, setup, settings?


Do they have an inbuilt failsafe ect?
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C-3PO

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Re: Heart stopping moment!
« Reply #5 on: May 27, 2022, 10:43:11 am »

From the Planet T7 manual

PLANET 7 FAILSAFE
The Planet 7 2.4GHz radio system has an easy to operate built in programmable failsafe system. Channel
No:1 (throttle channel) can be programmed to return to its preset position if the signal is lost. Channels No:
2,3 & 4 return the their to neutral position if the signal is lost.

Channel No:1
To set your throttle failsafe-preset position simply make sure the throttle stick is in the idle position then turn on your
transmitter. Now turn on the receiver.


Once the receivers LED has stopped flashing and is solid you have set the failsafe. It is
always recommended to have the failsafe set in the lowest position possible

Hope that helps/works

Regards
C-3PO
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ChrisH1981

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Re: Heart stopping moment!
« Reply #6 on: May 27, 2022, 10:52:20 am »

From the Planet T7 manual

PLANET 7 FAILSAFE
The Planet 7 2.4GHz radio system has an easy to operate built in programmable failsafe system. Channel
No:1 (throttle channel) can be programmed to return to its preset position if the signal is lost. Channels No:
2,3 & 4 return the their to neutral position if the signal is lost.

Channel No:1
To set your throttle failsafe-preset position simply make sure the throttle stick is in the idle position then turn on your
transmitter. Now turn on the receiver.


Once the receivers LED has stopped flashing and is solid you have set the failsafe. It is
always recommended to have the failsafe set in the lowest position possible

Hope that helps/works

Regards
C-3PO


Thanks! Yes I follow this proceedure as the throttle stick is already centred due to the spring.


Another scenario could be at play here....If the main batteries are plugged in BEFORE powering on the receiver, could this produce the symptoms im experiencing? Reason being, when main batteries are connected and I first power on the receiver, the motors run full speed (presumably in reverse) for 1-2 seconds before stopping (this is when boat is on the lakeside prior to launch)
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C-3PO

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Re: Heart stopping moment!
« Reply #7 on: May 27, 2022, 11:11:43 am »

Try the following.

1. Temporarily disconnect the power to the ESC
2. Set TX throttle stick to mid position ( likely to be in that position due to spring) and power on TX
3. Power on RX only (NO ESC) and observe RX flashing light - wait until it stops flashing.
4. Power off RX
5. Power off TX
6. Cross fingers :)


7. Reconnect ESC to power supply (with power switch off)
8. Power on TX (throttle mid stick)
9. Power on RX and ESC

Hopefully the motor will not run at startup, check throttle works forward and reverse and motors stop mid stick

Then with motor running (stick say half throttle),  power off TX and hopefully motors should stop

Regards
C-3PO
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ChrisH1981

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Re: Heart stopping moment!
« Reply #8 on: May 27, 2022, 11:13:46 am »

Try the following.

1. Temporarily disconnect the power to the ESC
2. Set TX throttle stick to mid position ( likely to be in that position due to spring) and power on TX
3. Power on RX only and observe RX flashing light - wait until it stops flashing.
4. Power off RX
5. Power off TX
6. Cross fingers :)


7. Reconnect ESC to power supply (with power switch off)
8. Power on TX (throttle mid stick)
9. Power on RX and ESC

Hopefully the motor will not run at startup, check throttle works forward and reverse and motors stop mid stick

Then with motor running (stick say half throttle),  power off TX and hopefully motors should stop

Regards
C-3PO


Thanks...good advice, I will give it a try  :-))
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Capt Podge

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Re: Heart stopping moment!
« Reply #9 on: May 27, 2022, 11:27:37 am »

... and, if you haven't already done so, make sure Tx trim tabs are set in neutral position.  :-)


Ray.
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ChrisH1981

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Re: Heart stopping moment!
« Reply #10 on: May 27, 2022, 11:28:50 am »

... and, if you haven't already done so, make sure Tx trim tabs are set in neutral position.  :-)


Ray.


 :-))
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