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Author Topic: Motor starting up on its own with the TX turned off  (Read 4160 times)

Fastfaz

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Motor starting up on its own with the TX turned off
« on: July 02, 2016, 12:49:38 PM »

Greetings everyone,
     Has anyone ever had the following problem- I have just rewired a trawler using a Micro Gyros FR40 ESC, inline fuse on the positive side, Planet T5 TX and RX running on 6 volt SLA battery. After re binding the RX everything worked fine (had to reverse the rudder,no problem) I then inadvertently turned off the transmitter first within a few seconds the motor started full bore until I switched off at the boat. I tried this several times and its fine if you turn off the boat first then the transmitter i.e. usual method,as I have wired everything the same way as I normally would I am struggling to understand how the motor is getting the voltage/power to operate with the TX turned off.
     I switched off the TX again and the motor started after a few seconds so I switched the TX back on getting no response from the controls at first (I am aware of the T5 delay) then suddenly the controls worked again. As I have borrowed the T5 I do not want to damage it but I'm baffled as to how and why this is happening. I borrowed the T5 to test out the wiring as I am awaiting the arrival of a Spectrum AR610 RX so I can us my DX6 transmitter, any help or advice on this will be greatly appreciated.
       Thanks for looking.
           Cheers,
                Faz.
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canabus

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Re: Motor starting up on its own with the TX turned off
« Reply #1 on: July 02, 2016, 01:44:50 PM »

The basic problem is turning off the TX!!!
Disconnect all the addons and re bind the TX to the RX!!
With the 2.4G new stuff, turn off the RX and then the TX.
Always turn the TX and then the Rx, or it gets it's knicks in a knot.

I have been down these road and loss a bit of hair!!!
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inertia

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Re: Motor starting up on its own with the TX turned off
« Reply #2 on: July 02, 2016, 01:52:41 PM »

There may be a dozen different reasons why this occurs but the BIG ONE AT THE TOP OF THE LIST is that there's no valid signal being received. The failsafe in the Tx/Rx circuitry may be conflicting with the failsafe in the ESC. Quite why is anyone's guess BUT but you should ALWAYS switch the Tx ON first and OFF last, irrespective of whether the radio is VHF, UHF or microwave in frequency. That way any unexpected burst of power and consequent danger from it is avoided.

"Doctor, Doctor! When ever I go like that I get a blinding headache. Can you fix it?"
"Yes, Mr Cooper - just don't go like that!"

(It's the way I tell 'em)

DM
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unbuiltnautilus

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Re: Motor starting up on its own with the TX turned off
« Reply #3 on: July 02, 2016, 02:55:20 PM »

Failsafe on the throttle channel is shutting down your glow engine powered plane on loss of signal. Only problem is the Tx doesn't know you are running a boat with both forwards and backwards functions. Switch the throttle function to the other stick, all should be well, as it does not have the same failsafe function......or do as previously posted and turn off model before Tx. Oh..and always unplug your battery!
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inertia

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Re: Motor starting up on its own with the TX turned off
« Reply #4 on: July 02, 2016, 03:17:24 PM »

I dug out the notes I wrote for a failsafe unit we made (called SparkOut) for petrol-powered models. It explains what failsafe is and does - and it will probably scare the hell out of you unless you've already found out about it. The bottom line is that you should ALWAYS know what might happen if the receiver suddenly loses contact with the transmitter i.e. will the motors stop or go to full reverse. You find out very easily by switching the TX off with the Rx still on - but only do this with the model out of the water! Hope it's useful:

 Irrespective of the frequency of radio transmission (MHz or GHz) all proportional servos operate the same way. Regular pulses of electricity are sent from the receiver along the signal wire to the servos; this is the wire which is neither black nor white. The duration of these pulses varies in length between about one and two thousandths of a second, or milliseconds (mS), depending on the position of the stick or switch which controls that channel from the transmitter. These pulses control the position of the servo. For example, full speed might be a signal of 1.9mS while slow throttle would be 1.1mS. Moving the trim lever will stretch the pulse length at one end of the scale or the other. Any signal with a pulse length of less than around 0.9mS or more than 2.2mS will be ignored by the servo as it is ‘invalid’ (remember this word for later). OK so far? Jolly good!This is all fine while the transmitter and receiver are in contact with each other, but what happens if the transmitter is suddenly switched off or the model goes out of range? That depends upon whether or not the radio is equipped with a failsafe function and, if it is, how that function works.If the radio has no failsafe function then the receiver becomes open to any rogue signals on the same or nearby radio frequencies. In extreme cases these signals can make the servos twitch or even lock-up at one end of their travel. Generally, however, the servos simply freeze in the position they had when the transmitter signal failed. Naturally if this involves full throttle then the model will become out of control with the engine at full speed – not exactly a safe state of affairs!If the radio has a failsafe then the receiver will briefly send a signal of some sort to the servos when the transmitter signal is lost. That way the servo positions will not be affected by any rogue signals from an outside source. The basic failsafe function will return the servos to a fixed position before reducing the length of the signal pulses to zero. Thus a Planet T5 will momentarily feed a signal of 1.5mS to centre each servo before the signals become 0.0mS – which is an invalid value and will be rejected by the servos, freezing them in the centre position Other radios will go immediately to this zero signal value, thus freezing the servo in its most recent position by (again) sending an invalid signal to the servos. This is typified by the Spektrum DX5e.
More sophisticated radios have computerised functions and the user can program what the throttle servo will do if the radio fails. They can either be programmed to freeze the servos at their last known “good signal” position (which is not a good idea, as we have already decided) or to move the throttle servo to a pre-set position. If you have one of these sets then you MUST select the second option i.e. a preset throttle position. This position should be with the throttle stick and throttle trim both fully down (= dead slow)*. Some radios have a Throttle Cut button which will generate the same “dead slow” signal when pressed. Examples of this type of radio are the Futaba 6EX, Futaba T6J, Hitec Optic 6 and Spektrum DX6i. In all cases the Instruction Manual for the radio will give directions on how to set the failsafe signal. If you have lost the manual then most can be viewed or downloaded from the Internet.
(*Remember this was written for a gas-powered model where fully down stick = engine stopped. For an electric model with forward and reverse speed control the corresponding stick and trim positions are in the centre)
DM
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Tugtower

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Re: Motor starting up on its own with the TX turned off
« Reply #5 on: July 02, 2016, 04:51:08 PM »

Some aircraft transmitters have a fail safe.... (which got mentioned)

when the transmitter is off the receiver goes into fail safe mode, which in many cases is actually about 1/4 speed  forward motion ( i have seen some do reverse ) in the cases where an aircraft type radio system is used last thing you want is the aircraft to fall from the sky like a brick, so the fail safe has a preset to give the aircraft contentious motion to avoid such brick falling incidents.

In use on a boat same principle. No signal, the motor will spin up until signal is established. The ESC has no control until the transmitter signal is restored, the ESC will power motor at the fail safe set position from the receiver.

Spectrum DX5e & 6's have this issue, in which case there is a method to shut the ''preset' learnt fail safe position off.

Check your manual on for your radio set to see if there is a way to alter the fail safe position or turn it off.

Bob K

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Re: Motor starting up on its own with the TX turned off
« Reply #6 on: July 02, 2016, 05:42:02 PM »

Thanks for the technical info, especially Dave M.

The most usual cause of loss of signal is going out of range, where you end up dead on the water.
Wouldn't it be nice if for model boats the fail safe mode brought the model back to where it was 'launched.
Some quad rotor drones have this capacity built in, so why not for boats?
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inertia

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Re: Motor starting up on its own with the TX turned off
« Reply #7 on: July 02, 2016, 08:07:48 PM »

Some quad rotor drones have this capacity built in, so why not for boats?
Now there's a cue for Mr R. Duino and his teccy acolytes.
Personally I don't sail that far away from me, largely because of my crummy eyesight and the finite extents of Papplewick Pond.
There's usually a low-tech solution for most of these problems.... (See "Don't go like that" below)
DM
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Bob K

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Re: Motor starting up on its own with the TX turned off
« Reply #8 on: July 02, 2016, 10:21:19 PM »

I often like to cruise along the opposite bank of our lake (~250m) although the T5 manual states 100m range max, until it developed a fault and kept leaving me dead half way across - although still within spec.
I think I may have  damaged the aerial when I dropped it.  I now have another T5 which happily stays in control all the way across.   OK  Just me being perverse and pushing the limits.  %%

...but as you say "(See "Don't go like that" below)"
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Kipper

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Re: Motor starting up on its own with the TX turned off
« Reply #9 on: July 02, 2016, 10:52:27 PM »

Quote
Personally I don't sail that far away from me, largely because of my crummy eyesight and the finite extents of Papplewick Pond.

You don't mean that little puddle on the corner of Moor Rd. & Papp lane do you Dave ?

Would've thought Mill Lakes at the country park would have been a better venue, plus it's nearer to you.
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inertia

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Re: Motor starting up on its own with the TX turned off
« Reply #10 on: July 02, 2016, 11:25:11 PM »

You don't mean that little puddle on the corner of Moor Rd. & Papp lane do you Dave ?

Would've thought Mill Lakes at the country park would have been a better venue, plus it's nearer to you.

I mean the pumping station cooling pond, which is about 7 miles from home and has a car park, cafe, toilets, concrete edging all round, sheltering trees, no weed and no fish. Entry to the site and use of the pond requires membership of the Papplewick Trust, so there are no casual/public users like those with RTF plastic speedboats. No-one sails large models and it's as big as the model boat lake at Wicksteed Park (which is a smashing venue).  ;D

http://papplewickpumpingstation.co.uk/
 
Mill Lakes is at Bestwood Park (4 miles) and apart from all other considerations appears to be a mecca for carp anglers, families with young children, water fowl and dog walkers. Too much potential for conflict there.
Size isn't everything  %)
Dave M
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steamboat66

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Re: Motor starting up on its own with the TX turned off
« Reply #11 on: September 05, 2016, 07:50:07 PM »

if you have failsafe set at throttle stick back, then the motor will go full reverse. re-bind your radio with the throttle stick in the "all stop" position. then it won't matter which is switched on or off first, the receiver will keep the motor off. this is how multi-rotor flyers set larger multis so as not to have them crash down to earth if the radio loses contact.
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Captain Flack

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Re: Motor starting up on its own with the TX turned off
« Reply #12 on: September 06, 2016, 01:08:11 PM »

 "this is how multi-rotor flyers set larger multis so as not to have them crash down to earth if the radio loses contact."

Sorry to hijack the thread but could you explain this please, as I assume you mean auto rotate and unless they aren't fixed pitch you can't auto them.  As far as I am aware, but I stand to be corrected. :-)
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steamboat66

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Re: Motor starting up on its own with the TX turned off
« Reply #13 on: September 07, 2016, 08:18:58 PM »

no, not auto rotate. multirotors fly by an onboard computer. when set to "altitude hold", the centre position of the throttle stick = hold altitude. move the stick up, and the multi goes up, stick down, multi down. if the throttle failsafes to full down, the multi will drop like a stone. so we set the throttle to half way, or just a little less, and the function to return home, if it's available. then the multi will either land slowly, or (preferably) return to where it started. most good 2.4 GHz receivers will put ALL channels to the set failsafe position. no one needs to worry about motors starting by themselves these days.
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microgyros

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Re: Motor starting up on its own with the TX turned off
« Reply #14 on: September 07, 2016, 08:50:54 PM »

if you have failsafe set at throttle stick back, then the motor will go full reverse. re-bind your radio with the throttle stick in the "all stop" position. then it won't matter which is switched on or off first, the receiver will keep the motor off. this is how multi-rotor flyers set larger multis so as not to have them crash down to earth if the radio loses contact.

To anyone who has a planet radio. Can the later planet receivers have the throttle channel failsafe programmed in this way?
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Ken G121

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Re: Motor starting up on its own with the TX turned off
« Reply #15 on: September 07, 2016, 10:15:59 PM »

Easy to fix. As radios intended for aircraft use some on loss of transmitter signal issue full reverse from output 3 of the receiver, thus forward only ESC or glow plug motor go to cut off, great for planes no good for boats.. in mode 2 (throttle left) left stick outputs to channel 3, right stick to channel 2 (elevator).
So open radio as long as there is a mode switch inside select it to mode1 (throttle on right stick) now your right stick outputs on channel 3,  aware if you have a servo connected to fore/aft on right stick this will go to full reflection on radio switch off.
The important thing is your left stick which you still use for throttle is outputting on receiver output 2 . Do plug your ESC into here and no problem. Only output 3 has the fail safe do do not use it. It is no good saying always switch off boat first ,what if signal loss is due to out of range or transmitter battery flat, result CARNAGE.
If you do not have a mode switch inside the radio then you need 6 small lengths of wire and a soldering iron. Then you can unsolder the 2 potentiometers operated by the stick fore,/aft movement 3 tags on each and use the wires to electrically connect them to the opposite circuit board. My ,4 channel Radio link system had a mode switch so first method worked, my Radio link 6 channel had no mode switch so I used second option. Honestly it is not difficult
But if you intend to sail a boat that goes to full reverse on loss of radio signal, please do not be on the same lake as me. But this problem CAN easily be solved
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microgyros

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Re: Motor starting up on its own with the TX turned off
« Reply #16 on: September 07, 2016, 11:09:56 PM »

The information I have been able to obtain from other Mayhem threads on planet radios is that oldest receivers somehow would fail safe on non-throttle channels but it was revised to a sustain after signal loss.
Rejigging the transmitter sticks may have prevented Fastfaz-Peter's drama. Bit if my assumption is correct then the alternative channels on loss of signal would continue to force a reverse if contact was lost while going astern. OK for aircraft but that wouldn't be my description of suitable for a boat-throttle failsafe.
The Planet radio pdf (known to be outdated) says the loss-of-signal condition is stored on powering up the receiver. Can any Planet radio user confirm that is the case or is it fixed by stick positions at the time of binding, as steamboat66 suggested?
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Ken G121

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Re: Motor starting up on its own with the TX turned off
« Reply #17 on: September 08, 2016, 09:29:14 AM »

Hi
My experience has been with radio link system certainly the older 6 channel receivers failed safe when signal lost, no output from any receiver channel. The 7 channel receivers available now have a pre programmed output on channel 3 on signal loss, all other channels give no output. So for me opening the radio selecting mode 1 and connecting my speed controller to No 2 (elevator) on the receiver worked just fine. I imagine many budget systems do the same thing. Give it a try you have nothing to loose
Ken
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steamboat66

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Re: Motor starting up on its own with the TX turned off
« Reply #18 on: September 17, 2016, 03:45:59 PM »

as i said earlier, modern 2.4 GHz radios have the option of setting ALL channels to the position they were at upon binding. as i don't like the idea of a non self centering throttle for either cars or boats, i will use the elevator channel for throttle. then when i bind the receiver, i'll have motor OFF rudder CENTERED and any other functions OFF. there will be NO uncontrolled motor problems on my boat. 
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microgyros

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Re: Motor starting up on its own with the TX turned off
« Reply #19 on: September 17, 2016, 04:09:35 PM »

...The Planet radio pdf (known to be outdated) says the loss-of-signal condition is stored on powering up the receiver. Can any Planet radio user confirm that is the case or is it fixed by stick positions at the time of binding, as steamboat66 suggested?

I thought that was an unequivocal way of putting it, even for people who didn't know there were spec changes in the Planet receiver failsafe. If no Planet radio user can confirm either way then I shall find out tomorrow.
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Ken G121

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Re: Motor starting up on its own with the TX turned off
« Reply #20 on: September 17, 2016, 08:20:30 PM »

Again not sure about planet system but radio link being a budget system does not have the facility to programme a fail safe position. The receivers that are a problem have a programme embedded in the receiver that can not be got rid of . On signal loss they give a reverse command on output 3 for throttle, I thus do not use output 3 for throttle. On one boat because I wanted rotating guns I used output 3 . If I switch the radio off the gun goes to full deflection, but I can live with that, better than a boat in reverse
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